Valorisation of Food Processing Wastes into High-Value Platform Chemicals: Industrial Pathways and Circular Bioeconomy Perspectives

Abstract

The world’s food industry faces significant obstacles today as it strives to meet the nutritional needs of its rapidly expanding global population while also managing an immense amount of food processing waste (FPW) generated throughout the entire food supply chain. The widespread use of traditional disposal techniques for food waste (landfilling and incineration) regularly faces challenges related to environmental sustainability and economic efficiency. This manuscript reviews the necessary transition from a linear “take-make-dispose” approach to food production to a more circular model that recycles food waste into high-value intermediate chemicals and renewable energy through the development of biorefineries. The manuscript explores the biochemical composition of food waste, with carbohydrates, lipids, proteins, and bioactive materials, making it a suitable feedstock for different multi-stage biorefinery operations. In addition, this review will evaluate a variety of existing conversion technologies for food processing waste, such as biological methods (e.g., anaerobic digestion and fermentation) and thermochemical methods (e.g., pyrolysis, gasification, and hydrothermal liquefaction), to create various platform chemicals, including organic acids, bio-alcohols and volatile fatty acids (VFAs), as well as the production of sustainable biofuels and biopolymers. The review also elucidates the three most determinative constraints on large-scale industrial implementation of food waste valorisation: feedstock variability, techno-economic feasibility, and the need for comprehensive life cycle assessments (LCAs). The alignment of food waste management strategies with the UN SDGs (in particular, SDG 12 ‘Responsible Consumption and Production’ and SDG 13 ‘Climate Action’) reflects the opportunity for food waste to serve as a foundation for a carbon-neutral, sustainable future. This review provides a strategic roadmap for academics, practitioners, and policymakers to tap into the full potential of food waste through a sustainable circular economy model.

1. Introduction

Food processing waste (FPW) generated by households and industries poses a global threat with significant environmental and economic repercussions. A crucial element of human nourishment, the food industry paradoxically generates substantial quantities of waste, encompassing liquid pollutants and solid refuse such as fruit and vegetable peelings and husks [1]. FPW is notably challenging to manage and, when disposed of, can harm human health and exacerbate environmental contamination. Moreover, precipitation and humidity led to the leaching of hazardous chemical compounds from waste materials into the soil and eventually into water bodies. Food across the supply chain, from agriculture to retail, accounts for 13% of worldwide food production; thus, its effect extends beyond just disposal logistics [2].

FPW consists of carbohydrates, vitamins, lipids, proteins, and other components that can be converted into valuable biofuels such as bioethanol and biodiesel, as well as other value-added co-products, including bioplastics, various platform chemicals, and other products. According to estimates, the demand for food and energy resources would increase to accommodate the projected global population of 9.8 billion by 2050 [3]. The 2022 SDGs progress report indicated that unsustainable consumption and production patterns are a fundamental reason for climate change, biodiversity loss, and escalating pollution. Therefore, a worldwide consensus has emerged on the need to adopt and cultivate sustainable practices to address these concerns [4]. The United Nations Environment Programme (UNEP) reports that food waste generated in retail, educational institutions, and households totalled 1.05 billion tonnes per year in 2022, indicating that 19% of food reaching the consumption stage is subsequently wasted [5]. It is estimated that 8–10% greenhouse gas emissions can be attributed to this waste. In light of the significance of this issue, the United Nations established 17 Sustainable Development Goals (SDGs) in 2015, advocating a 50% reduction in food loss in the supply chain at the consumer level by 2030. It facilitates access to affordable and clean energy (SDG 7) and reduces food waste (SDG 12.3). In 2024, UNEP reported that food waste continues to rise [6,7]. The scale of this waste necessitates a fundamental shift in our approach to managing food manufacturing wastes.

A range of measures is being implemented to reduce food waste. Some organic waste is treated by anaerobic digestion to produce biogas and by composting to produce soil amendments. Some by-products are used to produce animal feed, keeping them out of landfills [6]. But such systems often provide only a partial answer, since they are limited in scalability, applicability to different waste streams, and the extent of value recovery. In addition, stringent environmental regulations and the rising costs of current waste-disposal methods are driving the need for more innovative, cost-effective alternatives [7]. The perception of food waste as a beneficial resource rather than a nuisance is gaining greater acceptance.

Under these circumstances, valorisation of food by-products is highlighted as an effective strategy. Valorisation refers to the transformation of these waste streams into various added-value products through various technologies and processes [8]. The eradication of FPW seems an impractical objective, so recovering value from it is an essential measure. Additionally, crude oil prices experienced significant volatility, plummeting to as low as 20 USD/Bbl during COVID-19 and soaring to 120 USD/Bbl amid the war. Adverse events frequently impede progress toward the SDGs, exacerbating the hunger crisis and underscoring the need to identify alternative energy sources and enhance the recovery and reuse of energy and resources lost to food waste [9].

FPW contributes $1 trillion to global economies every year, according to the Food and Agriculture Organisation (FAO) of the United Nations. The beverage sector produces 26% of all FPW; the dairy sector produces 21%; fruits and vegetables produce 14.8% of FPW; and cereals produce 12.9%. In addition to harming the economy, FPW also contributes to environmental pollutants such as methane emissions, which contribute to the greenhouse gas levels. Developing effective methods to repurpose waste will help meet the United Nations SDGs by 2030 and create opportunities for sustainable bioeconomy development. Food waste continues to be generated in large amounts at both the national and regional scales, with the most recent United Nations studies estimating that roughly 63.1 million tons of food waste were generated in the United States in 2018 [10]. Approximately 88 million tons are generated annually in the EU, amounting to an estimated economic cost of EUR143 billion, with approximately 70% generated by households [11]. Food waste generated per capita ranges from 158 to 298 kg/year in Europe, while in developing countries, many of which lack national statistics on food waste, much less is known. For instance, despite being home to the world’s largest population and economic power, no national data on food waste is currently available from China. The statistics for France indicate approximately 5.8 to 9 million tons of food waste generated annually, or 20 to 30 kg per individual per year. The statistics indicate that the total amount of food currently wasted globally is sufficient to make a significant contribution to food security and poverty alleviation, while also avoiding substantial costs and environmental damage.

Approximately 95% of the food produced ends up in landfills, which creates high levels of human-caused methane emissions. Research indicates that methane produced from food waste amounts to approximately 113 million tons per year, which is equivalent to about 2.7 tons of carbon dioxide (CO₂) per ton of food disposed of in a landfill. Education is an effective way to reduce food waste. In Arizona, awareness campaigns have led to a 27.85% reduction in food waste [12]. However, the UN Environment Programme (UNEP) report from 2024 shows that food waste generation is either increasing or stabilising at an unsustainable level, as improved data enable us to quantify the problem more accurately. The complete elimination of food waste is unrealistic because some level of food loss will always occur; therefore, recovering value from food waste is a necessary and practical approach [13]. The high moisture content and biodegradable properties of food waste contribute to increased greenhouse gas emissions, with every ton of food waste releasing more than 2.7 tons of CO₂ into the atmosphere. The amount of CO₂ emitted from food waste exceeds 120 million metric tons globally each year, accounting for approximately 20% of methane emissions and releasing a significant amount of nitrous oxide. Nitrous oxide has a greenhouse warming potential of 25 times that of CO₂ and 300 times that of CO₂. Waste disposal practices vary greatly from country to country. Brazil recycles only 9% of its municipal waste. All Municipal Solid Waste (MSW), 34% of which can be recycled, 45% of which is organic and biologically/physically suitable for composting [14], is not recycled or composted. Conversely, South Korea uses state-of-the-art waste management technology and has achieved approximately 95% recycling of food waste [15]. Indonesia (where 62% of food waste is processed using bioprocessing methods) is transitioning towards sustainable waste management practices [16]. Although adequate, China has yet to establish waste minimisation standards, and 60% of MSW is landfilled every year [16,17].

Meanwhile, approximately half of the municipal waste generated by citizens in the United States is still landfilled despite the United States having a high-quality waste management system [18]. Approximately 46% of municipal waste generated in South Africa is sent to landfill [19]. Still, the disparity between MSW resources and waste-disposal mechanisms creates areas of cooperation and conflict outside Europe. The 2024 Yale Environmental Performance Index (EPI) highlights global disparities in waste management practices. The Solid Waste section of the EPI examines all countries for per capita waste generated, controlled waste treatment, and material recovery efficiency [6]. Some of the highest-performing countries with respect to recycling and energy-from-waste are Singapore, Japan, and Sweden, while many countries, due to inadequate legislative mechanisms and/or lack of infrastructure to support recycling/or energy-from-waste strategies, continue to trail Nigeria on the list of recycling and/or energy-from-waste progress [20].

This review advances understanding of how to produce industrial chemicals, fuels, and other products from waste materials. Although a lot of current research looks at the creation of industrial chemicals and fuels from single waste materials (e.g., simple anaerobic digestion of only food waste) or using a specific type of waste material (e.g., producing value-added chemicals from citrus peels), this manuscript provides a holistic view of the integration of multiple technologies (biological, thermochemical, and physicochemical) to convert waste materials into high-value products. This paper presents a new perspective on the utilisation of biomass for producing value-added products, emphasising what is termed “cascading uses” of biomass. Specifically, there is a need to extract value-added bioactive compounds from biomass and convert raw biomass into bulk chemicals to ensure a successful economic return. Recent literature supports the potential of biopolymers (e.g., PHAs) as a component of a circular economy; however, this paper goes one step further by identifying key industrial pathways from raw biomass to value-added products and determining areas of potential “bottlenecks” (e.g., substrate variability) in moving the technology forward commercially. Furthermore, industrial demonstrations and practical implementation experiences provide compelling evidence for the scalability, technological readiness, and commercial viability of food waste biorefinery technologies, thereby supporting their broader adoption within a circular bioeconomy framework [21]. This review combines laboratory-scale microbial engineering results with consideration of new microbial strains, such as Yarrowia lipolytica, and practical examples of how these technologies have been successfully used in industries beyond the laboratory, such as Novamont [22]. In doing so, it provides an integrated framework for technical innovations in green catalytic systems and biogas production via two-stage anaerobic digestion, forming a strategic plan for implementing the “Zero Waste” initiative. This review goes beyond the theoretical nature of sustainability to provide an objective, operational, industry-related roadmap for converting liabilities associated with food processing into stable, bio-based economic assets. Thus, this paper makes a unique contribution to the contemporary scientific landscape.

Conducting this review involved searching the following major scientific databases: Scopus, Web of Science, PubMed, ScienceDirect, and Google Scholar using numerous combinations of keywords including “food processing waste”, “valorisation of food waste”, “platform chemicals”, “biorefinery”, “circular bioeconomy”, “biofuels”, “bioplastics” and “sustainable development goals.” All literature collected for this review was peer-reviewed articles, literature reviews, industry reports or policy documents, most of which were published from 2010 to 2025. Technology reports, industry applications/use and development, sustainability assessments, and policy changes were all significant aspects of the selection process for this literature review because they relate to the valorisation of food waste. Only literature analysing the selected subjects defined in the scope of this review was included to provide a fair and complete synthesis of current scientific knowledge relevant to each of the identified subjects.

While several recent reviews address different aspects of food-waste valorisation, including biochemical conversion to single platform chemicals, single biorefinery pathways, or general circular bioeconomy concepts, this review differs in three interrelated ways. Initially, it adopts a system-level approach, followed by an industry-focused perspective, integrating biological, thermochemical, and physicochemical routes across the entire value chain instead of treating them in isolation. After that, this review emphasised cascading pathways, prioritising high-value bioactive extraction before bulk conversion, and identified decision points and economic trade-offs. At last, it couples laboratory-scale microbial and catalytic innovations with operational case studies and techno-economic analysis to convert heterogeneous FPW streams into scalable, high-value bioproduct portfolios.

Table 1. Summarising this review differs from recent published reviews.

Recent Review	Focus	Scope	How the Current Review Differs
[23]	Food-waste biorefinery and circular economy	Broad discussion on the conversion of food waste into biofuels and platform chemicals	Provides a more integrated, industry-oriented roadmap that links multiple technologies and their cascading uses.
[24]	Circular bioeconomy and biorefineries	General biorefinery concepts across biomass streams	Focuses specifically on FPW and practical Valorisation bottlenecks
[25]	Urban biorefinery from food waste and sewage sludge	VFA, PHA, and biogas recovery	Covers a wide spectrum of FPW conversion routes and industrial relevance
[26]	Food waste valorisation technologies	Thermochemical, biochemical, and chemical routes	Emphasises cascading Valorisation and practical solutions towards development
[27]	Circular pathway and advanced FW Valorisation	Includes thermochemical, biological, and green extraction	Highlights high-value products along with different conversion methodologies, with their industrial case linkage

compares the present review with recent literature and highlights that, unlike prior reviews focused on single pathways, broad circular-bioeconomy themes, or individual product classes, this work provides an integrated and industrially relevant roadmap for cascading valorisation of food-processing waste.

2. Classification and Characteristics of Food Processing Wastes (FPWs)

Different factories, including hospitals, food processing industries, and home-cooked waste, have contributed to various biodegradable FPW categories, categorised by components such as plant-, animal-, grain-, and milk-based materials. The predominant component of FW is vegetables, accounting for 23–65%, followed by animal waste (19–44.2%), and grains (16–32.7%). Vegetable, fruit peels, and pulp debris are classified as plant-based FW, whereas dairy products, meat, and egg shells are animal-based FW [28,29]. On the other hand, grain-based FW rely mostly on nine species of plants from the Gramineae family, such as rice, wheat, sorghum, corn, oats, rye, triticale, millet, and rye-wheat triticale.

Food waste often had a high moisture content (74–90%), volatile solids-to-solid ratios (80–97%), and organic materials including protein (15–25%), carbohydrate (41–62%), and lipid (13–30%). Reports indicate that plant-based FW contains a comparatively higher amount of volatile matter, i.e., 72.3–80.0%, than animal-based FW (1.4–7.8%) [27,28]. Furthermore, certain animal-based FW has been documented to possess a lower fixed carbohydrate content, ranging from 1.01–2.8%, while only eggshell FW demonstrates a significantly higher level at ~23%. In contrast, plant-based FW exhibits a significant fixed carbon content, especially fruit peel-based FW (11.3–24.3%) [30] (

Table 2. Global production rate of different types of food processing waste [6].

Food Waste	Category of Waste	Origin of Waste	Production (MMT)
Citrus and banana peels	Vegetables	Fruit and vegetable processing plant, Starch manufacturers	114.1–124.7
Fish waste	Animal	Marine industry, fish processing plants	2
Waste cooking oil	Animal and vegetable	Vegetable processing plant, distilleries, fish and egg processing plants	4.5
Dairy product	Animal	Milk processing industry	275

). Notably, the fruit peel FW exhibits a substantial phosphorus concentration of 28.2%, specifically in banana peel at 25%. Additionally, banana peels contain significant amounts of cellulose (60–65%), hemicellulose (6–8%), and lignin (5–10%). In vegetable waste, potassium concentration ranges from 25–38%, whereas animal-based FW, particularly in fishbone waste and eggshell, exhibits elevated levels of calcium (68.8%) and magnesium (15.4%) [31,32]. In addition to macronutrients, the micronutrients zinc and manganese are also found in animal-based FW. Similarly, cereal-based foods like wheat bran are rich in several micronutrients, soluble and insoluble dietary fibres, alkylresorcinols, essential amino acids, unsaturated fatty acids, ferulic acids, minerals, and sterols. Moreover, different phytochemicals, including flavonoids, phenolics, carotenoids and phytosterols are present in varying configurations.

Food waste is currently managed through burning, sanitary landfill disposal, and anaerobic digestion to produce bioenergy and bioproducts such as organic acids, biopolymers, and chemicals. Even within the biorefining framework, these processes could be integrated with the extraction of valuable constituents from waste, including proteins, colourants, and secondary metabolites such as phenolics and alkaloids. In this regard, the combination of FW also influences the fermentation process. For example, the presence of carbon, nitrogen, and phosphorus substrates in FW-derived media significantly influences fermentation performance, impacting yields and productivities [33]. A crucial aspect of conversion regime design is reducing fluctuations in substrate concentration in conversion media. Therefore, to bridge this knowledge gap and offer valuable insights for developing methods to utilise FW more effectively, it is crucial to quantify the degree of variation within these FW and assess their impact on the feasibility and efficacy of bioconversion methods.

3. Concept of Platform Chemicals

Platform chemicals can serve as feedstocks for the production of high-value-added chemicals. For instance, a prevalent chemical agent in nylon production is adipic acid, which can be synthesised from biomass by converting glucose into glucaric acid, then to adipic acid [29]. In this context, glucose is regarded as a platform chemical for the synthesis of adipic acid. Thus, platform chemicals serve as substrates for the production of secondary intermediates and final products. As the principles of the green bioeconomy are integrated into industry, the manufacturing of platform chemicals could serve as a renewable, sustainable feedstock, garnering considerable attention. As mixed FPW are abundant in nutrients and diverse organic materials, they can be converted into platform chemicals, including organic acids, alcohols, and furfural, using various chemical and biotechnological methods [30]. In this way, it offers benefits by treating substantial amounts of FPW concurrently and producing platform chemicals such as organic acids (lactic acid, citric acid, and succinic acid), volatile fatty acids (VFAs), and ethanol. The different pathways for synthesising platform chemicals from food waste are illustrated in Figure 1.

Organic acids such as citric acid, propionic acid, lactic acid, and malic acid are widely utilised compounds across many industries, particularly in the formulation of food and beverage ingredients and pharmaceuticals. Moreover, organic acids are identified as the primary results of kitchen waste fermentation [34]. Currently, chemical synthesis of these acids is employed, with the end products or intermediate components serving as feedstock in biochemical cycles. In pursuit of sustainable alternatives, FW could be a potential renewable resource, as its composition is well-suited to fermentation. For instance, lactic acid is produced via anaerobic fermentation of glucose, a process that can readily be carried out on various fibre waste streams. Lactic acid has been used in the food and pharmaceutical industries due to its carboxylic and hydroxyl groups, which can be converted into other potentially valuable products such as pyruvic acid, acrylic acid, and 1,2-propanediol. Sugar obtained from FW is generally utilised by different microorganisms, such as Lactobacillus, at 36 °C and pH 6.0, yielding 0.5 g g⁻¹ of lactic acid. Fermentation of FW is reported to yield a combination of l-lactic acid and d-lactic acid under mesophilic conditions at 52–55 °C and pH 5.5–6.0 [31] (Table 3).

In contrast, bacteria such as Bacillus coagulans only synthesise L-lactic acid under thermophilic conditions at temperatures above 55 °C. Similar to lactic acid, citric acid is utilised in the food and beverage industry and in cosmetics as a preservative and flavouring agent [32]. Moreover, citric acid is increasingly prevalent in the biomedicine sector, where it serves as an active component in the synthesis of various biopolymers for applications in nanomedicine and drug delivery systems.

While citric acid occurs in various plant species, a significant portion of commercially available citric acid is synthesised through fermentation processes using microorganisms, including bacteria, fungi, and yeasts. The microbial synthesis of citric acid from renewable sources, such as FW, is considered an essential technique because numerous substrates, including sucrose, starch, cane, and beet molasses, are readily available and cost-free. Another organic acid, like succinic acid, serves as a fundamental precursor for the synthesis of many chemicals, primarily 1,4-butanediol (BDO), polybutylene succinate (PBS), and polybutylene succinate (PBS) and polybutylene succinate (PBS). Moreover, it can substitute for numerous benzene-derived commodities and petrochemical intermediates, leading to a significant decrease in production-related pollution and a reduction in the synthesis of 250 benzene-derived compounds. Wheat bran is a significant substrate for the production of salicylic acid via solid-state fermentation using Aspergillus awamori and A. oryzae. These microorganisms produce various amylolytic and proteolytic enzymes that break down the complex polymers present in FW, enabling their easy conversion into valuable products. The enzymatic hydrolysis of vegetable and fruit waste using a fungal strain resulted in a succinic acid yield of 1.2 g g⁻¹ and a production rate of 1.3 g L⁻¹ h⁻¹ [35].

The decomposition of organic constituents in FW by microbes under anaerobic conditions yields biofuels (ethanol) and biogas (methane and hydrogen). In particular, microorganisms such as Clostridium and Thermoanaerobacter spp. are attracting interest for thermophilic industrial processes due to their inherent ability to ferment a wide range of carbohydrates into ethanol [32]. However, the capacity of Thermoanaerobacter sp. to ferment hemicellulose-derived sugars in FW and its tolerance to elevated ethanol concentrations make it a more advantageous option than Clostridium sp. [36]. Glycerol is also a by-product of the manufacture of bioethanol. The “thin stillage” left after distillation of the ethanol contains ~2% (w/v) glycerol. Therefore, valorisation of FW into ethanol could produce another valuable platform chemical, such as glycerol [36].

Volatile fatty acids (VFAs) are linear, short-chain carboxylic acids with 2–6 carbon atoms and are valuable in the chemical industry as precursors to diverse compounds, including alkanes, ketones, esters, aldehydes, and alcohols. Therefore, VFAs present in FW are currently utilised in biofuel production. In particular, the proteins present in plant- and animal-based FW influence the VFAs profile of FW. For example, tofu protein waste yielded acetic, butyric, and valeric acids at a ratio of 56:10:18. In contrast, animal-based FW yielded the same VFAs at a ratio of 1:1:1 [37]. Often, VFAs synthesised from FW are reported to be converted into glycerol by Yarrowia lipolytica. Crude glycerol has been regarded as an economical raw material for biotechnological applications, and under nitrogen-limited conditions, Y. lipolytica synthesised substantial quantities of microbial lipids strains [38]. In addition, FWs are reported to serve as potential feedstocks for medium-chain fatty acids (MCFAs) via anaerobic fermentation owing to their excellent biodegradability [39]. It would reduce waste remediation costs while facilitating effective product recovery. While fermenting FW into MCFAs, maintaining pH and effectively regulating the anaerobic chamber are critical determinants for high-yield production. It will eventually influence the subsequent conversion processes, including hydrolysis, acidogenesis, and acetogenesis [40].

Another platform chemical, furfural (FF), and 5-hydroxymethylfurfural (HMF) can be generated from FW biomass. Mostly, non-edible lignocellulosic waste from FW is converted into FF and HMF through acid-catalysed dehydration of hexose sugars for HMF and pentose sugars for FF. Common FW sources include hazelnut shells, tea leaves, corn cobs, and rice straw, which are utilised as feedstock for FF and HMF synthesis. Sometimes, different catalytic systems that use metal chlorides (CrCl₃, FeCl₃) and ionic liquids are employed to enhance yields [41]. For example, melon rind waste has been converted using Montmorillonite KSF clay at 180 °C temperature for 30 min, volumetric tetrahydrofuran: water ratio (3:1) for the production of 5.9% hydroxymethylfurfural [42], (Table 3).

Table 3. Different platform chemicals are synthesised from food processing waste.

Feedstock Type	Conversion Process	Pretreatment (Microorganism/Enzyme/Catalyst)	Conversion Process	Platform Chemicals	References
Sugar obtained from food waste	Lactic acid fermentation	Lactobacillus sp.	-	l-lactic acid and d-lactic acid	[31]
Citrus peel	Dark fermentation	Escherichia coli and Clostridium species	-	Biohydrogen	[43]
Sweet sorghum waste	Acetone-butanol-ethanol fermentation	C. acetobutylicum	-	Biobutanol	[44]
Rice starch	Catalytic conversion	Pinewood sawdust-derived biochar activated by phosphoric acid	150 °C temperature for 20 min volumetric dimethyl sulfoxide: water ratio (3:1)	Glucose (86.5 mol%)	[45]
Food waste collected from the students’ canteen	Two-stage enzymatic treatment	Amylase and glucoamylase	1st stage: enzyme dosage = 150 U g(TS)−1; pH = 5.5 2nd stage: enzyme dosage = 150 U g(TS)−1; pH = 4	Reducing sugar (204.2 g L−1)	[46]
Food waste collected from the university	Microbial fermentation	Bacillus sp. AM5	55 °C and pH 10.5	Total volatile fatty acids (34.8 g L−1)	[47]
Melon rind waste	Catalytic conversion	Montmorillonite KSF clay	180 °C temperature for 30 min volumetric tetrahydrofuran: water ratio (3:1)	Hydroxymethylfurfural (5.9% wt)	[42]
Food and beverage waste	Catalytic conversion	Glucoamylase conversion followed by Amberlyst 36	140 °C temperature for 40 min dimethyl sulfoxide: water ratio (1:1)	Hydroxymethylfurfural (71% mol%)	[47]
Food waste collected from the municipality	Microbial fermentation with engineered microbes	Genetically modified Yarrowia lipolytica	T = 28 °C pH = 6	Succinic acid (54.4 gL−1)	[48]
Sweet potato waste	Anaerobic fermentation with engineered microbes	Genetically modified Escherichia coli	T = 37 °C; t = 48 h	Succinic acid (18.65 g L−1)	[49]
Simulated food waste	Mesophilic fermentation	Lactobacillus amylolyticus	T = 52 °C; pH = 5.5	Lactic acid (0.57 g g−1)	[50]

Table 3. Different platform chemicals are synthesised from food processing waste.

Feedstock Type	Conversion Process	Pretreatment (Microorganism/Enzyme/Catalyst)	Conversion Process	Platform Chemicals	References
Sugar obtained from food waste	Lactic acid fermentation	Lactobacillus sp.	-	l-lactic acid and d-lactic acid	[31]
Citrus peel	Dark fermentation	Escherichia coli and Clostridium species	-	Biohydrogen	[43]
Sweet sorghum waste	Acetone-butanol-ethanol fermentation	C. acetobutylicum	-	Biobutanol	[44]
Rice starch	Catalytic conversion	Pinewood sawdust-derived biochar activated by phosphoric acid	150 °C temperature for 20 min volumetric dimethyl sulfoxide: water ratio (3:1)	Glucose (86.5 mol%)	[45]
Food waste collected from the students’ canteen	Two-stage enzymatic treatment	Amylase and glucoamylase	1st stage: enzyme dosage = 150 U g(TS)−1; pH = 5.5 2nd stage: enzyme dosage = 150 U g(TS)−1; pH = 4	Reducing sugar (204.2 g L−1)	[46]
Food waste collected from the university	Microbial fermentation	Bacillus sp. AM5	55 °C and pH 10.5	Total volatile fatty acids (34.8 g L−1)	[47]
Melon rind waste	Catalytic conversion	Montmorillonite KSF clay	180 °C temperature for 30 min volumetric tetrahydrofuran: water ratio (3:1)	Hydroxymethylfurfural (5.9% wt)	[42]
Food and beverage waste	Catalytic conversion	Glucoamylase conversion followed by Amberlyst 36	140 °C temperature for 40 min dimethyl sulfoxide: water ratio (1:1)	Hydroxymethylfurfural (71% mol%)	[47]
Food waste collected from the municipality	Microbial fermentation with engineered microbes	Genetically modified Yarrowia lipolytica	T = 28 °C pH = 6	Succinic acid (54.4 gL−1)	[48]
Sweet potato waste	Anaerobic fermentation with engineered microbes	Genetically modified Escherichia coli	T = 37 °C; t = 48 h	Succinic acid (18.65 g L−1)	[49]
Simulated food waste	Mesophilic fermentation	Lactobacillus amylolyticus	T = 52 °C; pH = 5.5	Lactic acid (0.57 g g−1)	[50]

Since 1920, various solid waste products, such as starch-based foods, maize cannery waste, and sugarcane molasses, have been utilised for ethanol production. Moreover, liquid food waste from the beverage industry contains a high amount of sugar (10–12% w/v), which could be utilised directly for ethanol synthesis. For example, watermelon juice containing fermentable sugars at 7–10% w/v and free amino acids at 15–35 µmol mL⁻¹ is reported to support bioethanol production. Moreover, annual consumption of 45 million metric tons (MMT) comes from 45–60% of total fruit peel waste, with 40% from tomato processing. Bio-butanol, often referred to as butyl alcohol, is frequently utilised as a solvent, extractant, supplement, eluent, and precursor in the synthesis of various chemicals. Additionally, processing 675 MMT of globally produced paddy yields 136 MMT of rice husk, 45.4 MMT of rice bran, 40.8 MMT of broken rice, 27.2 MMT of unripe rice, and 6.4 MMT of discoloured rice. Starch-rich FPW serves as a major feedstock for biobutanol production via pretreatment, followed by utilisation of the extract with bacteria from the Clostridiaceae family [51].

Nevertheless, the direct conversion of FW into a specific renewable chemical is nearly unfeasible due to the complex composition and significant variability across food and beverage sectors. Consequently, the generation of platform chemicals from FW must be followed by enzymatic treatment, i.e., saccharification, mechanical pretreatment, and chemical hydrolysis [52]. The synthesis of platform chemicals from FW has garnered increasing interest and demonstrated significant potential. The majority of these chemicals are derived from petroleum, making their prices highly dependent on crude oil markets. On the other hand, substantial global FPW generation presents an opportunity to utilise it as a feedstock for the synthesis of platform chemicals, thereby reducing reliance on fossil-fuel-based chemicals.

4. Conversion Technologies for Platform Chemical Production

4.1. Biological Processes

Biological conversion employs microorganisms or their derived enzymes to convert FW into various platform chemicals under mild conditions, offering a sustainable alternative to chemically synthesised routes. The significant pathways are fermentation, anaerobic digestion, and culture consortium bioprocessing, often involving hydrolysis to release fermentable sugars and volatile fatty acids (Table 2). The fermentation of FW, a crucial process in sustainable waste management solutions, entails the decomposition of organic waste by microorganisms into ethanol [45]. Various microorganisms, including bacteria and yeast, are used; in particular, the conventional yeast Saccharomyces cerevisiae is widely utilised for fermentation. As FW contains a complex mixture of polymers, it is difficult to ferment it directly using ethanol-producing microbes. Therefore, different pretreatment methods, such as heat, thermochemical, chemical hydrolysis, and enzymatic methods, are typically required to break down the polymer into monomers, enabling microorganisms to convert them into ethanol. For example, starch-based FW are heated to high temperatures, then α-amylase is added to degrade the starch polymer. Glucoamylase is also used to convert liquid starch in FW into glucose. Previous studies have reported ethanol concentrations of approximately 29 g L⁻¹ from food waste fermentation following enzymatic hydrolysis and amyloglucosidase treatment [53]. Fermentation can be aerobic or anaerobic, depending on the microorganism used. In this regard, anaerobic digestion is an effective technique in which microorganisms decompose organic FW under anaerobic conditions, producing biogas consisting of methane, carbon dioxide, and other trace gases [54]. It contains four stages: hydrolysis, acidogenesis, acetogenesis, and methanogenesis, carried out by various microorganisms, including thermophilic and mesophilic organisms. Microorganisms belong to the genera Bacteroides, Clostridium, and Synthrophobacter [55].

The FW treatment through the fermentation process has been adapted from rural to urban areas at both small and large scales, offering energy recovery potential in underdeveloped regions. Nevertheless, the overall economic feasibility of the process must be evaluated, and additional research is required to improve it and make the process more cost-effective. Over the last 10 years, the integration of engineered microbes into the biovalorisation of FW into high-value products has increased considerably. The advancement of targeted, precise gene-editing technologies has accelerated progress in systems and synthetic biology, creating new opportunities to augment or instil specific functions in microbial hosts. These advancements enable bacteria to produce novel chemicals or improve the efficacy of conventional fermentation processes. According to earlier investigations, a genetically modified Escherichia coli strain HD134 achieved a succinic acid yield of approximately 0.9 g g⁻¹ when cultivated on sweet potato waste hydrolysate [56]. Thus, a modified Yarrowia lipolytica strain has been engineered to synthesise high-value compounds such as itaconic acid, limonene, and farnesene from cooking oil waste. In another report, an engineered strain, Y. lipolytica PSA02004, converted FW into succinic acid, yielding 0.4 g g⁻¹ [48]. He et al. investigated this potential through the interaction of engineered Y. lipolytica, C. glutamicum, and B. amyloliquefaciens, which synergistically decompose starch and oil in food waste, supplying the requisite precursor for B. amyloliquefaciens to synthesise various lipopeptides. In general, Pseudomonas putida is a resilient bacterium recognised for its capacity to degrade organic substrates in FW. Interestingly, genetically modified P. putida shows greater promise for conversion [57]. It induces enzymatic digestion of FW, which transforms monomers into insulin and polyhydroxyalkanoate (PHA) [58]. Microorganisms produce a diverse array of enzymes in FW, including amylase for starch degradation, cellulase for cellulose and hemicellulose degradation, laccases and lignin peroxidase for lignin modification, protease for protein degradation, and lipase for lipid degradation. Initially, enzymatic methods are utilised to break down complex polymers in FW, which can then be further converted into various biomaterials, including polyphenols, compost, and other products via fermentation and anaerobic digestion. A schematic overview of biological, physicochemical, and thermochemical valorisation pathways for food waste conversion is presented in Figure 2.

4.2. Thermochemical Processes

Thermal pretreatment is a technique that applies high temperatures to disintegrate and transform the FW, followed by treatment with chemical agents and catalysts, including acid and alkali agents, for final processing. The principal purpose of heat treatment is to transform waste into a usable form while minimising the presence of toxic and pathogenic microorganisms. Compared with biological routes, these methods are usually significantly faster and can handle poorly sorted waste more directly [56,59].

Pyrolysis is a thermal process that decomposes organic waste at high temperatures (400–900 °C), for a short duration of only 8–12 min under anaerobic conditions. It has been employed for many years to generate biomass from charcoal; however, its application in transforming garbage into valuable products is still in its infancy [56]. Polymeric materials in FW are decomposed into smaller molecules, yielding end products such as bio-oil through pyrolysis. It is primarily used for the production of various platform chemicals, metallurgical applications, flue-gas purification, etc. Pyrolysis is classified into four types: slow, quick, flash, and catalytic [53]. In slow pyrolysis, FW are subjected to gradual decomposition at a rate of 6 °C min⁻¹, resulting in greater biochar production.

In comparison, in fast pyrolysis, the heating rate is set higher at 300 °C min⁻¹, resulting in a substantial yield of bio-oil. In flash pyrolysis, FW are rapidly heated for a short time, leading to increased production of various oils and gases [54,58]. However, the quality of pyrolysis oil typically depends on different catalytic processes, in which elevated temperatures with a catalyst enhance gas production while reducing char output. Moreover, the pyrolysis reaction depends on the residual time, temperature, and feedstock composition. Therefore, standardisation of these variables could enhance the synthesis of high-value products from hard shell GW, such as palm shell, coconut shell, and rice husk [59,60].

Furthermore, recent studies on porous-media-based thermal systems have highlighted the importance of heat-transfer optimisation and thermal uniformity in improving reactor performance and energy efficiency, providing useful design principles for advanced thermochemical conversion technologies and industrial-scale biomass processing [59].

Gasification is a specialised method for waste management that has garnered considerable attention for its resource recovery. This process entails the thermal transformation of solid–liquid waste carbonaceous substances into a flammable gaseous product by applying different gasification agents, such as CO₂, H₂, hydrocarbons (CH₄), and inert gases. Gasification is conducted at high temperature (700–1500 °C) with a controlled amount of oxygen or steam [61]. In the direct gasification method, an oxidising agent oxidises the feedstock and maintains the necessary reaction temperature, whereas in indirect gasification, the reaction proceeds without any oxidising agents. A gasification system comprises a gasifier, necessary for generating combustible gas, a cleaning system for removing hazardous compounds from the combustible gas, and an energy recovery system. Another thermochemical process, termed hydrothermal liquefaction, converts organic waste from FW into liquid bio-oil under high pressure and temperature, with the presence of water. Converting low-value waste into a profitable, energy-abundant product presents a viable approach for effective utilisation [62].

4.3. Physicochemical Methods

Physiochemical methods refer to analytical techniques where FW are converted into platform chemicals by combining both physical and chemical reactions to release fermentable sugars, including glucose, reducing sugar and intermediates such as VFAs, and organic acids. To synthesise high-value chemicals from FW, dehydration reactions are essential for aqueous-phase catalytic processing of the feedstock.

Recent advancements in this domain are examined comprehensively, focusing on low-energy and non-thermal processing methods (supercritical fluid, microwave, cold plasma), biological pretreatments (utilising ligninolytic microorganisms and enzymes), thermochemical technologies (hydrothermal carbonisation, pyrolysis), and innovative cascade strategies for multi-product recovery.

Solid acid catalysts enhance aqueous-phase dehydration owing to their cost-effectiveness, reduced environmental impact, and recyclability [62]. As a result, investigations are going on numerous catalysts, such as phosphates and nanoscale mixed oxides, to assess their feasibility for individual-atom or alloy-based influence on biofuel production. Currently, it is reported that the majority of single-atom alloy catalysts exhibit higher catalytic activity across many chemical processes, including hydrogenolysis and hydrogenation synthesis. This single-atom catalyst consists of individual atoms coordinated to surface atoms of appropriate host materials, offering an alternative method for modulating catalytic activity.

4.3.1. Acid–Base Hydrolysis

Hydrolysation treatment with acid and alkali agents exhibits distinct effects on acidogenic hydrolysis of FW. Acidic reagents, such as sulphuric acid and hydrochloric acid, resulted in increased soluble organic matter during hydrolysis by transforming carbohydrates in FW into simple sugars. On the other hand, alkaline reagents, such as sodium hydroxide and ammonium hydroxide, adversely affect the process by generating toxic species during hydrolysis. Thus, acidogenic hydrolysis of carbohydrates reaches 80%, whereas proteins range from 40–70%. Notably, during acidogenic fermentation of FW, hydrolysis of proteins acts as a rate-limiting step, as the proteins present in FW (both vegetable and animal waste) influence the profile of VFAs synthesised during food waste processing. For instance, acidogenic hydrolysis followed by fermentation of tofu waste protein yielded acetic, butyric, propionic, and valeric acids, whereas animal protein, such as egg protein, resulted in a low amount of VFAs. Not just protein; lipid molecules in FW are reported to be disrupted, producing long-chain fatty acids and glycerol. Interestingly, synthesised glycerol serves as a substrate in fermentation.

However, long-chain fatty acids generally attach to the cell walls of different FW, affecting nutrient delivery and inhibiting anaerobic bacterial fermentation. Moreover, temperature also influences acetic acid fermentation. For instance, thermophilic and hyperthermophilic microorganisms have been shown to enhance acidogenic hydrolysis in FW fermentation, facilitating the synthesis of hydroxylates essential for microbial metabolism during the process. An elevated temperature also led to substantial proliferation of microorganisms belonging to Thermotogaceae and Clostrridiaceae, thus enhancing hydrolysis and acidification. In this regard, Zhang et al. [45] devised a two-stage enzymatic hydrolysis process for FW valorisation to address the challenges posed by the insolubility of macromolecular compounds in FW, in which amylase was used initially, followed by the application of glucoamylase in the second stage under different conditions. In another report, 71% of HMF was produced from FW using Amberlyst. The major conversion methodologies and efficiencies for platform chemical production from food waste are presented.

4.3.2. Cold Plasma-Assisted Extraction

Cold plasma is an innovative non-thermal technology that generates reactive oxygen and/or nitrogen species, contingent upon the feed gas utilised for plasma generation. The fundamental principle of cold plasma involves utilising primarily electrical or electromagnetic fields to generate diverse ions, radicals, free electrons, and molecules in their fundamental or excited states through the interaction with feed gas and media. The temperature of heavier species varies from 300 to 1000 K, whereas electrons can attain temperatures exceeding several 10,000 K [63]. This non-equilibrium condition and UV light efficiently elicit different thermodynamically unfavourable physicochemical processes in the pretreated sample. Additionally, the produced species’ high temperatures are confined, preventing sample heating. This is crucial for thermosensitive biological compounds like plant-based wastes [64]. Cold plasma pretreatment can be dry or wet, depending on the result. Anari et al. [65] extracted walnut shell micro- and nano-cellulose fibres using dry dielectric barrier discharge (DBD) plasma treatments. The method involved dewaxing, hemicellulose removal, and bleaching. The method used cold plasma at various times. Plasma-purified cellulose, making it better for processing, according to product analysis. Plasma pretreatment before hemicellulose removal and bleaching converted microfibrils to nanofibrils. A similar method was used by Zhu et al. [66] to isolate cellulose from sugarcane bagasse before DBD processing. Here, cellulose was combined with water prior to DBD plasma treatment. In that investigation, DBD-pretreated cellulose dissolved better than pure cellulose (the control).

4.3.3. Microwave-Assisted Extraction

Microwave irradiation could also be used as a controlled, moderate heating technique to efficiently disrupt the complex lignocellulose structure. When applied, this irradiation induces an explosion of plant cells by evaporating the present moisture, which creates immense pressure on cell walls [67]. Additionally, Zhu et al. [32] confirmed that heating induced by microwave irradiation could cleave Cα–Cβ bonds for efficient degradation of lignin and lignin-like structures in FPW. To ensure enough moisture in the substrate before processing, microwave irradiation is often combined with different acids, alkalis, or organic solvents. Mladenović et al. [68] studied pretreatment of corncob using a microwave reactor with alkaline hydrogen peroxide, focusing on key process parameters, such as microwave power, pretreatment duration, hydrogen peroxide dosage, and biomass-to-alkali ratio. Under optimal conditions, around 75% of lignin was removed within a 1 min pretreatment. As a result, hexose and pentose yields obtained after enzymatic hydrolysis were 2.7- and 5.6-fold higher compared to the untreated corncob. Microwave processing is considered energy-efficient, cost-effective, and eco-friendly, enabling uniform heating in a short reaction time with minimal generation of side products. Yet, some difficulties must be overcome when shifting to industrial scale-up, such as high capital investment, high operating expenses at high loads and high pressure, as well as ensuring sufficient moisture within the biomass sample [69,70].

4.3.4. Supercritical Fluid Extraction (SFE)

SFE uses solvents above their critical temperature and pressure, combining liquid-like density, gas-like diffusivity, and low viscosity for efficient penetration of solid matrices. The most often utilised solvent, supercritical CO₂, is nontoxic, recyclable, and functions at low temperatures, conserving thermolabile components like antioxidants and polyphenols. Increased heat and pressure during extraction may increase lipophilic chemical release [71,72]. SFE effectively isolates nonpolar molecules like essential oils. To extract polar biomolecules like polyphenols and water-soluble vitamins, polar cosolvents like ethanol or methanol are needed, as supercritical CO₂ alone cannot dissolve them. Cosolvents improve efficiency and cost-effectiveness by lowering the necessary temperature and pressure [73]. Aussanasuwannakul et al. [74] found that supercritical CO₂ with ethanol significantly boosted phenolic content (0.45 mg GAE/g) and antioxidant capacity (0.195 mg TE/g) in soybean residue extracts compared to pure CO₂. The low-temperature operation of SFE retains bioactive chemicals with health benefits, such as anticancer and antiviral properties, making it ideal for converting fruit/vegetable waste into nutraceuticals. Moreover, SFE efficiently transforms agro-waste into biodiesel (70% efficiency) and bioactives without harmful solvents (

Table 4. Platform chemicals are synthesised from food processing waste through various conversion methodologies.

Main Product	Feedstock	Conversion Methodology	Conversion Efficiency (%)	References
Micro- and nano-cellulose fibers	Walnut shells	Cold Plasma-Assisted Extraction	~22–26%	[65]
Cellulose	Saccharum officinarum	cold plasma	60.88%	[66]
Hexose and pentose sugars	Corncob	Microwave-assisted	61.2% and 60.24%	[68]
Biopolymer (Polyhydroxyalkanoates, PHA)	Organic fraction of municipal solid waste	Acedogenic fermentation	114.4 g kg−1	[73]
Reducing sugar	Food waste	Two-stage enzymatic hydrolysis	204.2 g L−1	[74]
Methane		Anaerobic digestion-integrated with gasification	557–680 mL g−1
Biooil	Banana peel waste	Pyrolysis, 500 °C, 20 min	18–28%	[75]
Volatile fatty acids	Food waste	Fermentation	649 g kg−1	[76]
Methane	Municipal food waste	Anaerobic digestion	285.7 mL g−1	[77]
Biogas and biopolymer (Polyhydroxyalkanoates)	Urban food waste	Acidogenic fermentation	76 g kg−1 PHA and 0.44–0.51 m3	[78]

).

A FW biorefinery transforms a wide variety of waste into valuable products of interest, including biofuels and platform chemicals. Understanding the composition of FW and the intended final product synthesis is crucial for selecting an efficient bioconversion method for incorporation. Food waste biorefinery processes are categorised into three pathways: biological processes comprising the transformation of FW through microbial enzymes, thermochemical processes focusing on FW processing at high temperature with chemical additives, and chemical processes involving the application of different catalysts and solvents. Sometimes, two or more methods are integrated to enhance the conversion efficiencies. From an economic point of view, such integrated processes make the whole process more profitable.

On the other hand, mixing two different types of waste also enhances the synthesis of the final product. For example, mixing of starch-based FPW with poultry manure increases the dark fermentation process, producing biohydrogen yield from 4.1–5.03 mol kg¹. At the same time, residual biomass was employed for biodiesel production by Chlamydomonas reinhardtii [79].

However, among all FPW conversion technologies, anaerobic digestion stands out as the most practical and economically viable option, offering 90% energy recovery within a limited time period. The main advantage is that, during anaerobic digestion, high-moisture food waste can be used without drying, making this process ideal for wet FPW [80]. On the contrary, fermentation is associated with acid or alkali hydrolysis for converting high complex sugars into monosaccharides, which are further utilised to produce biofuels. Therefore, a pretreatment step is required to achieve ~80% sugars [81]. In the case of wet FPW, the HTL method is also among the best, yielding 47–52% biocrude with 71% recovery.

Nevertheless, its highest capital cost (USD 1500–2000/ton) affects the whole production process [82]. In this regard, gasification offers superior energy recovery, but it requires drying and operates at extreme temperatures (800–1500 °C), eventually harming the feedstock. Among all conversion technologies, the pyrolysis method is the fastest, but has lower conversion efficiency (~50%) [83]. A comparative summary of the major FPW conversion technologies is presented in

Table 5. Critical comparison of important food processing conversion technologies [84,85].

Parameters	Fermentation	Anaerobic Digestion	Pyrolysis	Gasification	Hydrothermal Liquefaction (HTL)	Acid/Base Hydrolysis
Primary product	Bioethanol, biohydrogen, VFAs	Biomethane, digestate	Biooil, biochar, syngas	Syngas (H2 and CO)	Biocrude oil	Fermentable sugars
Energy yield	42% ethanol	90% energy recovery	52% biooil yield	1.2 m3/kg syngas	47–52% biocrude; 68–71% energy recovery	86.8% sugar conversion
Carbon conversion	Variable (13–27% H2 efficiency)	High (76.7% vs. removal)	52.3%	63.6%	65–67%	~87%
Advantages	Low energy input with low temperature and atmospheric pressure	Highest environmental benefit with low carbon emissions, with high energy recovery	Fast process and works with diverse waste streams	Highest hydrogen fraction with lowest operation costs	Ideal for wet biomass with the highest biocrude yield	Highest sugar conversion efficiency
Limitations	Downstream processing is required	Long retention time required	High capital cost.	A very high temperature is required.	High pressure is required.	No final energy product is synthesised.

.

5. Biorefinery Approaches for Food Waste Valorisation

Once a promising fermentation approach has been identified, an integrated biorefinery pathway toward scale-up; however, its industrial feasibility depends on process robustness, feedstock consistency, downstream separation efficiency, and overall techno-economic viability. The valorisation of food waste through biorefineries is increasingly promoted as a strategy to reduce environmental burdens, improve resource efficiencies, and align with circular bioeconomy goals. Still, this promise should be interpreted cautiously because food waste is highly heterogeneous, seasonally variable, and often contaminated, which complicates standardisation and process control [56]. Although biorefineries can convert food processing waste into renewable fuels such as bioethanol, biodiesel, methane, and hydrogen, the sustainability of these outputs is not automatic, since energy-intensive pretreatments, chemical inputs, and product purification can offset environmental gains if the system is not carefully optimised. Similarly, while the circular bioeconomy framework emphasises the co-production of bioenergy, platform chemicals, bioplastics, and animal feed with minimal waste generation, in practice, most systems remain far from zero waste because residual streams, inhibitory compounds, and separation losses persist [86]. Two-stage anaerobic digestion systems producing biohythane, or cascades that combine acidogenic fermentation with downstream hydrogen or methane recovery, demonstrate the value of sequential processing, but these systems also introduce greater operational complexity, higher capital requirements, and stricter control demands. Therefore, integrated biorefineries should not be presented simply as superior alternatives to single-product recovery; rather, they are potentially more resilient and resource-efficient only when product recovery, process integration, and market conditions are favourable. Their key advantages lie in maximising biomass utilisation, recovering multiple products from the same feedstock, and reducing disposal costs. Still, these benefits must be balanced against higher engineering complexity, uncertain product markets, and the risk that low-value residues may still require treatment. In this sense, food waste biorefineries are promising as a long-term circular strategy, yet their real industrial relevance depends on whether they can achieve consistent performance, acceptable recovery yields, and competitive economics at scale [87,88,89].

On the other hand, as the green chemistry principle has been implemented in the biorefinery approach, converting FW using green technologies will make the whole process more sustainable. Furthermore, diversifying the products, this multi-product FW biorefinery also adapts to market fluctuations, potentially generating a series of high-value chemicals when chemical compound prices decline [23]. The specific calorific properties of the extracted bio-based products from FW immediately enhance the economic value at an industrial scale. The quantity of preventable food waste can be managed to some extent through three strategies: elimination, reduction, and reuse. The integration of various bioprocesses offers the advantage of using organic-rich effluents, thereby enhancing product recovery and overcoming the constraints of individual processes.

6. Industrial Applications of Derived Platform Chemicals

Recently developed Platform Chemicals derived from Food Processing Waste are becoming increasingly important as intermediate materials linking fossil-fuel-based industries to bio-based industries. Many types of chemicals, such as Organic Acids, Alcohols, and Furan derivatives, are examples of multi-use chemicals that can be used for the production (as well as starting) of Fuels, Plastics, Pharmaceuticals, and Agrochemicals. Renewable Resource Utilisation via platform chemicals also increases efficiency of use of these resources by decreasing impact (via reduction) on the environment through conventional p/chemical methods. Moreover, due to the increasing global focus on the WCE (Waste to Circular Economy) and the valorisation of Waste, these products are being commercialised at an accelerated pace. The circular bioeconomy approach and industrial utilisation of food waste-derived platform chemicals are illustrated in Figure 3.

6.1. Biofuels and Energy Carriers

Biofuels derived from food processing waste represent one of the most commercially mature applications of bio-based platform chemicals. The production of biofuels from food processing waste plays a key role within the context of bio-based platform chemicals due to several reasons, including governmental mandates related to renewable energy and decarbonisation targets as a result of growing distrust in fossil fuels. Over the last decade, there has been a huge growth in the commercialisation of biofuels from food processing waste, particularly regarding bioethanol, biogas, biomethane, and biohydrogen. For example, the Beta Renewables facility in Italy illustrates the technical and economic viability of second-generation bioethanol production by converting agricultural and food- processing residues into transportation fuels [58]. Similarly, India’s National Bioenergy Initiative has facilitated the utilisation of large quantities of biomass residues for renewable energy generation [58]. Likewise, the increasing establishment of food waste in decentralised biogas plants shows the extent to which circular bioeconomy principles can contribute to sustainable energy generation.

The biofuels category is among the most advanced and used forms of platform chemicals from food waste. Bioethanol can be produced from carbohydrate-rich food waste, such as fruit skins, vegetable scraps, and cereal residue. To produce bioethanol from carbohydrate sources, complex carbohydrates from food processing waste must be broken down into small amounts of fermentable sugars through the use of an enzyme hydrolysis reaction. This process is followed by fermentation of sugar into ethanol using Saccharomyces cerevisiae (yeast), which provides ethanol with 98% purity [23].

Currently, second-generation bioethanol development from lignocellulosic biomass has moved beyond laboratory research to commercial production. As a case in point, Beta Renewables, located in Italy, has a facility capable of producing approximately 40,000 metric tons of cellulosic ethanol per year at a commercial scale using agricultural waste, illustrating the technical feasibility of this second-generation biofuels pathway [88]. A second example can be found in India, where many second-generation bioethanol facilities based on rice straw and other agricultural waste materials have been established through the National Bioenergy Mission, thereby reducing the reliance on fossil fuels [89]. However, biobutanol derived from food waste through ABE fermentation using Clostridium spp. is also an exciting biofuel alternative to ethanol. Very high energy density and better compatibility with existing transportation infrastructure make biobutanol a better choice in many circumstances compared to ethanol [90]. Anaerobic digestion is an established means of converting food waste into renewable energy in the form of biogas. In anaerobic digestion, microorganisms break down organic material in the absence of oxygen, producing a gas containing 50–70% methane [91]. As reported by the International Energy Agency [18], biogas plants around the globe had a total installed capacity of over 35 gigawatts (GW) (including substantial contributions from food and other organic waste) [92]. Countries, including Germany, China, and India, have widely implemented biogas technology within their waste management and renewable energy systems [93]. India continues to have thousands of decentralised biogas plants that convert food waste from households, markets, and food processing facilities into energy, while reducing food waste. The production of food waste into biohydrogen is becoming more popular, along with biogas and bioethanol. The use of bacteria immobilization for enhanced hydrogen production is gaining traction. Current research indicates that continuous bio- production of hydrogen from biomass hydrolysates has yielded approximately 2.83 mol/hydrogen for every mole of hexose over a 40-day period. While this yield is approaching four times greater than observed yields of standard strains (e.g., Bacillus thuringiensis), it is also providing complete value addition to date by-products (inedible/discarded portions of date fruit). That is to say, to date by-products using hot water extraction to create solvent syrup (35.5% sucrose, 11.80% glucose, 13.17% fructose), there were simultaneous production levels of 292 mL hydrogen gas and 235 mL CH₄/per gram of volatile solids. Collectively, these findings highlight substantial progress in the scale-up of biohydrogen production systems, with hydrogen yields increasing from laboratory-scale operations (46 mmol H₂ L⁻¹) to pilot-scale processes (73 mmol H₂ L⁻¹). These improvements have been largely attributed to the implementation of optimized operational conditions, including pH regulation and reduced hydrogen partial pressure, in conjunction with molasses-based substrates and the efficient fermentative capabilities of Clostridium butyricum. These advances underscore the feasibility of translating laboratory achievements into larger-scale applications and demonstrate the potential of industrial by-products as sustainable feedstocks for commercial biohydrogen production [94]. These results underscore the potential for large-scale biofuel production from food waste, as well as many other biobased energy applications.

6.2. Bioplastics and Biodegradable Polymers

Because of growing environmental concerns related to conventional petroleum- based plastics, there is a rapidly increasing need for sustainable, biodegradable, and bio-based products that can replace them. In that regard, platform chemicals such as lactic acid and succinic acid made from food waste will be critical for the transition to a circular bioeconomy. Lactic acid is produced primarily from the fermentation of carbohydrate-rich food waste using lactic acid bacteria (LABs). The monomer for polylactic acid (PLA), a biodegradable polymer, is lactic acid, and PLA has many uses such as packaging, textiles and biomedical devices. NatureWorks LLC is the leading producer of PLA, producing approximately 150,000 tons per year, and markets PLA under the Ingeo brand. PLA has many desirable characteristics, such as biodegradability, biocompatibility and good mechanical strength that create significant opportunities to replace conventional plastics. Succinic acid is a key biobased platform chemical produced through microbial fermentation using organisms like Actinobacillus succinogenes and Basfia succiniciproducens. Succinic acid serves as a precursor for synthesising polybutylene succinate (PBS), which is another biodegradable polymer used for agricultural films, packaging materials, and disposable consumer products.

The industrial viability of biobased succinic acid is demonstrated through Reverdia, the joint partnership between DSM and Roquette. Alongside PLA and PBS, PHAs (polyhydroxyalkanoates) are another category of bioplastics that can be made from food waste-derived substrates, and they are now being produced. PHAs can be produced by a variety of microorganisms grown under limited nutrient conditions, and they have been highlighted for their complete biodegradability and versatility as a plastic. For example, approximately 66% of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) was obtained from whey using pure cultures of Haloferax mediterranei in a fed-batch fermenter. In comparison, yields of 61.5% were obtained from cassava starch using Cupriavidus sp. KKU38 [95]. Another potential source of materials for bioplastics is protein-rich wastes, such as by-products from fish processing. Gelatin and myofibrillar proteins recovered from fish processing waste can be developed as alternative feedstocks for producing bioplastics, thereby adding another dimension to the potential of food waste for the manufacture of biopolymers [96].

6.3. Pharmaceuticals and Nutraceuticals

Food processing waste is a source of bioactive compounds, giving them great value for use in both pharmaceutical and nutraceutical applications. Waste products from food processing, such as citrus peels, grape pomace, apple skins, and tea waste, contain many antioxidants, polyphenols, flavonoids, and vitamins. For example, the juice industry produces substantial waste in the form of citrus peels, which are a very good source of pectin [97]. Pectin is commonly used as a gelling agent, stabiliser, and pharmaceutical excipient. The industrial extraction of pectin from citrus waste is a well-established process and contributes a significant amount to the valorisation of waste. Similarly, grapes are used to make wine, and grape pomace is a by-product of this process. Grape pomace is used to create nutraceutical formulations due to its high amount of resveratrol and other polyphenols, which provide antioxidant and anti-inflammatory properties [98]. Citric acid is one of the most widely used organic acids in the world, and it is produced through fermentation using the fungus Aspergillus niger. About 2.5 million tons of citric acid are produced worldwide each year, with a significant portion derived from agricultural or industrial waste sources, such as molasses or other food waste [99]. As a result, citric acid is used extensively in pharmaceuticals as an acidulant, preservative, and buffering agent. In the pharmaceutical industry, lactic acid is also used in controlled drug delivery systems. Lactic acid is used to produce biodegradable implants that dissolve naturally over time. Thus, food waste is an important feedstock for producing these products.

6.4. Agrochemicals and Food Additives

In both the agricultural and food sectors, many platforms are being developed from food waste products, offering a sustainable alternative to synthetic chemicals. The anaerobic digestion of food waste generates volatile fatty acids (VFAs), which include acetic acid, propionic acid, and butyric acid. They are very commonly used as an additive to animal feeds to enhance gut health and as preservatives for silage [100]. Organic acids and amino acids derived from food waste are also being used in agriculture as plant growth stimulators and soil conditioners. They help improve nutrient availability and create a more favourable soil structure to promote sustainable agriculture. For example, composting or fermenting food waste produces biofertilizers with high nutrient levels that are commonly used in organic farming practices [101]. Examples of food-grade additives include acetic acid, lactic acid, and citric acid. They are commonly used in food processing as preservatives, acidifiers, and flavour enhancers. They are increasingly being produced from renewable sources like biomass to meet the increased demand from consumers for clean-label, and natural products. For example, acetic acid is one ingredient that is used in making vinegar, which is also used as a food preservative. In addition to the supporting evidence from regulatory agencies (e.g., FAO, EFSA), bio-based compounds are widely accepted as safe by these same agencies for use in food and agriculture, providing further support for their use across industrial sectors [102]. Major platform chemicals, their feedstocks, industrial applications, and representative commercial examples are summarised in

Table 6. Major platform chemicals derived from food processing wastes, their production pathways, industrial applications, and representative commercial examples.

Platform Chemical	Feedstock Source	Conversion Process	Industrial Application	Commercial/Industrial Example	References
Ethanol	Fruit waste, lignocellulosic biomass	Enzymatic hydrolysis + fermentation (S. cerevisiae)	Biofuel, fuel blending	Beta Renewables (Italy)—40,000 tons/year	[103,104,105]
Biogas (Methane)	Mixed food waste	Anaerobic digestion	Electricity, heat, fuel	Germany biogas plants (>9000 units)	[91,99,106]
Lactic Acid	Starch-rich food waste	Lactic acid fermentation	PLA bioplastics, pharmaceuticals	NatureWorks LLC (>150,000 tons/year PLA)	[19,107,108]
Succinic Acid	Agro-industrial residues	Microbial fermentation (A. succinogenes)	PBS bioplastics, solvents	Reverdia (DSM-Roquette)	[92,109,110,111]
Citric Acid	Molasses, fruit waste	Fermentation (Aspergillus niger)	Food additive, pharmaceuticals	Global production > 2.5 million tons/year	[112,113,114]
Furfural	Hemicellulosic biomass	Acid hydrolysis	Resins, solvents, fuels	China (the largest producer globally)	[112,115,116]
Volatile Fatty Acids (VFAs)	Food waste slurry	Acidogenic fermentation	Feed additives, biofertilizers	Used in EU waste Valorisation plants	[93,117,118]
Pectin	Citrus peel waste	Acid extraction	Food, pharmaceuticals	Citrus processing industries (Brazil, USA)	[119,120,121]

. Table 6 demonstrates the high diversity of food waste-derived platform chemicals and their broad intersection with industry. Fermentation-based production pathways are the primary choice. They have a scalable, and cost-efficient production method compared to other types of production systems. Emerging technologies, such as acidogenic fermentation and catalytic conversion, are gaining much attention. Also, several of these pathways already have commercial production examples, which demonstrate that they have achieved industrial maturity in producing ethanol, lactic acid, and citric acid.

6.5. Market Opportunities, Commercial Risks, and Competitiveness of Food Waste-Derived Platform Chemicals

Many factors affect the market potential of platform chemicals produced from food waste, including technological viability, demand, production economics, policy support, and competition from existing petrochemical industries. While renewable products have environmental advantages, their large-scale use is subject to fluctuations in crude oil prices, availability of raw materials, and costs of downstream processing. This same finding has been noted for integrated biorefineries, where the economic viability of the system depends on the integration of the process and existing market conditions [88,89,122]. The most well-developed market for bio-based products is bioethanol. With the introduction of renewable fuel mandates in Brazil, the USA, India, and the European Union, there is a growing global demand. However, because of the sensitivity of second-generation ethanol’s production costs to crude oil prices, the low price of crude oil provides little incentive for the use of biofuels. In addition, there is a substantial capital cost associated with pretreatment, the production of enzymes, and purification, making it very difficult for new companies to enter the market. An example of a successful facility is Beta Renewables in Spain. At the same time, it demonstrates technical feasibility; the long-term profitability of the facility will depend upon alternative energy policies and a consistent supply of feedstocks [102]. The rapidly growing market potential of bioplastics such as polylactic acid (PLA), polybutylene succinate (PBS), and polyhydroxyalkanoates (PHAs) is being driven by stricter environmental legislation as well as bans and/or limitations on single-use plastics. However, compared to conventional petroleum-based polymers (e.g., polyethene and polypropylene), these materials have a significantly higher production cost. For instance, while NatureWorks is an example of an industrial producer with established capabilities for large-scale manufacturing of PLA, there are still significant roadblocks to achieving widespread adoption due to issues related to feedstock costs, fermentation efficiency, and downstream polymer processing requirements (for example, there are limitations associated with the high cost of production and the ability of PHAs to compete in the marketplace due to low productivity, high recovery costs, and limited economies of scale). Another source of opportunity in this area is organic acids (e.g., citric acid, lactic acid, succinic acid) that can be produced from sustainable sources and used as substitutes for many of the petrochemical intermediates used in the food, pharmaceutical, and polymer industries; however, their commercial viability is negatively impacted by volatility in the price of agricultural feedstocks and energy. For instance, bio-based succinic acid must continuously improve fermentation yields and purification efficiencies to remain competitive with traditional petrochemical routes based on maleic anhydride; likewise, the profitability of lactic acid production will depend on maintaining low-cost carbohydrate substrates as well as efficient microbial conversion systems. Major obstacles prevent companies from implementing a food waste biorefinery or industrial process. Issues include difficulty in standardising processes and assuring the quality of the products to be produced due to feedstock variation, seasonal fluctuations, risks of contamination, and uncertainty regarding the supply chain. Companies (small and medium-sized) also have issues obtaining the required funding to develop biorefineries using commercialised technology. Additionally, the length of time it takes to obtain government approvals for food products, pharmaceutical products, and agricultural products creates additional costs for bringing these technologies to market. This is particularly true in developing regions where the waste collection and distribution systems are not yet fully integrated. Despite the above limitations, there are many opportunities for companies to move quickly toward an industrial implementation of food waste biorefineries. Examples of governmental policies that create a business-friendly environment for companies to manufacture bioproducts: the promotion of renewable energy; the desire for carbon neutrality; extended producer responsibility; and the promotion of the circular bio-economy [123]. Because they produce multiple outputs (e.g., through producing both biofuels and organic acids), integrated biorefineries reduce business risk because of the diversification of revenue streams through producing many products from one feedstock. Additionally, due to an increase in consumer interest in environmentally sustainable products and green products, the market continues to be favourable to the implementation of food waste valorisation technologies. A comparative overview of major food waste-derived bioproducts, their petrochemical counterparts, market opportunities, commercialization challenges, and representative industrial examples is presented in

Table 7. Comparison of major food waste-derived bioproducts with their petrochemical counterparts, highlighting key market opportunities, commercialisation risks, and representative industrial examples that demonstrate their potential for advancing circular bioeconomy and sustainable industrial development.

Product	Petrochemical Counterpart	Major Opportunity	Key Commercial Risk	Industrial Example
Bioethanol	Gasoline	Renewable fuel mandates	Dependence on crude oil prices	Beta Renewables (Rivalta Scrivia, Italy)
PLA	Polyethene (PE)	Demand for biodegradable packaging	Higher production costs	NatureWorks (Ingeo®) (Plymouth, MN, USA)
PHA	Polypropylene (PP)	Complete biodegradability	Limited economies of scale	Pilot municipal biorefineries
Succinic acid	Maleic anhydride derivatives	Green polymer production	Expensive purification processes	Reverdia (DSM–Roquette) (Delft, The Netherlands)
Citric acid	Synthetic acidulants	Strong food and pharmaceutical demand	Feedstock price variability	Aspergillus niger fermentation industry
Biogas	Natural gas	Carbon-neutral energy generation	Feedstock logistics and storage	Decentralised Indian biogas plants

.

6.6. Safety Considerations, Contaminant Control, and Regulatory Compliance of Food Waste-Derived Products

In addition to providing substantial benefits to the environment and economy, food waste valorisation on a large scale must be addressed carefully when it comes to safety risks, managing contaminants, and complying with regulations. Food processing waste has a high degree of variability in terms of contaminants. It can contain everything from heavy metals and Pathogenic micro-organisms to pesticide residues and mycotoxins to pharmaceuticals and microplastics, which can negatively impact the quality and safety of products made from food waste [118]. Therefore, monitoring and treating products prior to use as a food contact material, drug, or for agricultural purposes is necessary. Food waste valorisation is associated with heavy metal contamination. Heavy metals will collect in food waste at various stages (collection, processing, and storage).

As a consequence, utilising biofertilizers, animal feed, or biopolymer products containing heavy metals will result in bioaccumulation and trophic transfer, thus impacting the health of humans and the environment. Consequently, products derived from food waste must be characterised by regular physicochemical analysis, with all heavy metal concentrations being below established regulatory thresholds set by, for example, the European Union and the EPA. Over the last few years, many different treatment methods, such as adsorption, membrane filtration, biochar-assisted remediation, and selective precipitation, have been increasingly utilised to reduce heavy metal concentrations in valorised food waste products [119].

Microbial contamination is a significant issue as well. Many food waste streams contain pathogens, such as E. coli, Salmonella spp., Listeria monocytogenes, and fungi that produce mycotoxins, making biological stabilisation methods, like thermophilic composting, anaerobic digestion, pasteurisation, and sterilisation, essential in mitigating microbial risks. The Animal By-Products Regulation from the European Union (EC No. 1069/2009) mandates that organic waste be thermally treated before being reused in agriculture, while the Food Safety Modernisation Act regulates preventive controls for biological hazards from food-derived goods. Both of these regulations are necessary for verifying safe applications downstream [97]. Compliance with regulations is crucial when the end use of food waste is expected to involve food contact, pharmaceutical, or biomedical applications. Regulations require that food contact polymers and packaging comply with migration limits set by the EC Regulation (EC) No. 1935/2004 and other directives regarding materials intended for food contact [120].

Additionally, pharmaceutical excipients and bioactive compounds obtained from food-processing waste must comply with Good Manufacturing Practice (GMP) standards and quality standards imposed by regulations such as the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA). Prerequisites for commercialisation include comprehensive toxicological assessments of the materials, traceability systems, and contaminant monitoring programs. Biofertilizers and soil amendments made from food waste must adhere to nutritional quality standards and limits for contaminants to be used in agriculture. The European Union (EU) Fertilising Products Regulation (EU) 2019/1009 establishes the maximum allowable levels of heavy metals and pathogens for organic fertilisers and biostimulants. Likewise, many country-specific regulatory bodies require regular verification of microbial indicators and chemical contaminants prior to their use on land. These requirements are particularly critical for preserving soil quality, protecting the balance of groundwater, and preventing contaminants from entering food chains. In addition to meeting any individual regulation requirements, integrated quality assurance frameworks are now being recognised as key enablers of support for sustainable food waste valorisation systems. Collectively, the HACCP principles, ISO 22000 food safety management systems, GAP and GMP provide a systematic process for identifying, monitoring and controlling the risks that may be encountered throughout the value chain. Lastly, implementing digital traceability tools and life cycle-based monitoring can provide additional assurance to consumers and enhance the potential for global market access.

7. Circular Bioeconomy and Sustainability Perspectives

Transforming food processing waste into platform chemicals is a key aspect of a circular bioeconomy. This model seeks to break the link between economic growth and the loss of resources and environmental degradation. In contrast to the traditional linear “take-use-dispose” approach, circular bioeconomy relies on the continual use of biological resources, reducing waste as much as possible, and restoring the natural environment (i.e., regenerating ecosystems). So, food waste should not be looked upon as a liability. Instead, it can provide a valuable source of energy, chemicals and materials when used as a feedstock. Through the incorporation of waste valorisation strategies within industrial systems, the efficient use of resources is not only enhanced but also plays a major role in mitigating climate change and building a sustainable future [106].

7.1. Resource Efficiency and Waste Minimisation

There is an enormous amount of Food Waste produced worldwide, amounting to a global concern that can have serious environmental and economic consequences. The FAO (Food and Agriculture Organisation of the United Nations) estimates that around 1.3 billion tonnes of food is wasted/lost each year, which represents almost one-third of all food that is produced. When we consider the amount of food wasted, it can be viewed as not just waste food itself, but also as a loss of the natural resources needed to produce food. Natural resources include: water, energy/chemicals, land, human labour and other inputs to food production [115]. Waste can be reused/recycled through the valorisation of food processing waste into bulk Chemicals Platforms, where there is an opportunity to recover those resources that have been wasted. For instance, residual (carbohydrate-based) products from food processing, such as fruit and vegetable peelings, can be converted into fermentable sugars, and then subsequently into organic acids or biofuels. Residual (lipid-based) products may be derived from food processing and can also be used to produce biodiesel, while residual (protein-based) products may be turned into amino acids or bioactive compounds [6]. Industrial use of waste valorisation technologies is showing high success in increasing resource efficiency. Within the European Union, integrated waste management systems have allowed for the diversion of a large volume of organic waste discharged from landfills for biogas production and composting. An example is the more than 9000 biogas plants operating in Germany, a significant number of which obtain food or agricultural waste as a feedstock; therefore, they recover energy and nutrients [121]. In addition, waste valorisation can increase efficiency by allowing for cascading use of high-value compounds that have been removed prior to recovering energy through mixed use of feedstock such as citrus peel waste. For example, there will be an extraction of the essential oils and pectin from the citrus peel, which would allow for maximum value to be recovered from the residual biomass through anaerobic digestion to produce biogas. Multi-stage use of feedstock corresponds to the principles of a zero-waste system.

7.2. Carbon Footprint Reduction and Climate Benefits

Using food waste as a substitute for fossil-fuel-based chemicals represents an economic opportunity to reduce greenhouse gas (GHG) emissions. Conventional petrochemical manufacturing processes utilise large amounts of energy and are among the largest contributors to global carbon emissions. In contrast, biological production methods utilise renewable natural resources and therefore, have less impact on the environment [116]. That bio-based production methods have a much lower environmental impact than petrochemical processes have been shown through life cycle assessment (LCA) studies. For example, one study found that microbially derived bio-succinic acid produces 60–80% less CO₂ than its petroleum-based counterpart, which has been attributed to both the use of renewable feedstocks and lower energy requirements to produce succinic acid [122]. Similarly, the carbon footprint for producing lactic acid from sugars derived from food waste is also significantly lower than for the fossil fuel-derived alternatives. Also, the downstream production of biodegradable polymers such as polylactic acid (PLA) will further contribute to reducing carbon emissions by displacing conventional plastics, which are one of the major contributors to environmental pollution [109]. The anaerobic digestion of food waste has an important part to play in the reduction of greenhouse gases and the adaptation to climate change. Organic waste that is sent to a landfill undergoes uncontrolled anaerobic decomposition and produces methane. Methane is a greenhouse gas that has a global warming potential of about 28–34 times the global warming potential of CO₂ when assessed over 100 years (IPCC) [109]. Through controlled anaerobic digestion systems (e.g., biogas plants), the amount of methane produced is prevented from entering the atmosphere, and at the same time, renewable energy is generated. Countries such as Sweden and Denmark are successfully integrating food waste-based biogas into their energy systems. In Sweden, biogas is widely used to power transportation as a fuel source, resulting in significant reductions in the consumption of fossil fuels and urban air pollution.

7.3. Life Cycle Assessment (LCA) Insights

Life Cycle Assessment (LCA) can be an important tool to evaluate the environmental sustainability of food waste utilization systems; LCA will assess the total lifecycle of the food waste utilization system from the point at which the feedstock is delivered to a food waste recycling facility, processed, utilized, and finally disposed of, and thus provide the evaluator with a large-scale picture of the sustainability of the various conversion methods used for food waste utilization [95]. Many LCA studies have shown that integrated biorefinery systems have better overall environmental impact than single-product conversion processes due to the possibility of using multiple streams of feedstocks and producing many different types of value-added products from each feedstock stream. This increases the efficiency of the use of resources and decreases the amount of residual waste produced in the conversion process. To illustrate, an integrated biorefinery system that converts food waste into bioethanol, organic acids, and biogas will have a much lower overall environmental impact than a system that produces only bioethanol [96]. The use of process integration also improves energy recovery, decreases greenhouse gas emissions, and provides better overall economic viability of the integrated biorefinery system [20]. The use of cascading utilisation strategies further enhances the overall sustainability of biorefineries. Cascading strategies involve first extracting high-value compounds (e.g., antioxidants and essential oils) from the food waste stream and then converting the remaining biomass stream into platform chemicals and energy carriers. The hierarchical utilisation of food waste ensures that the maximum amount of value is recovered from the food waste stream, and that the conversion methods are aligned with the principles of circular bioeconomy [118]. While LCA has numerous advantages, LCA studies have also identified multiple challenges. Collection, transportation, and preprocessing of feedstock are three areas where environmental burdens significantly affect the performance of a value chain overall. This finding underlines the necessity for optimised logistics and decentralised processing facilities in order to reduce both emissions and operational costs. LCA study results are complemented by techno-economic assessments, which provide a financial evaluation for potential food waste valorisation pathways. As an illustration, slaughterhouse waste-derived (PHA) polyhydroxyalkanoates cost significantly more than biodiesel when measured from the standpoint of production cost (EUR 1.41/kg to EUR 1.64/kg for PHA versus EUR 0.97/L for biodiesel), depending on whether the material would be classified as waste or as a potential co-production site for both products [50]. Payback periods associated with PHA are between 3.25 and 4.5 years, indicating that this project will generate revenues within an acceptable time frame commercially [124]. Economic benefits of recovering high-value compounds are also significant. An example of this is the tomato waste Valorisation project (supercritical CO₂) to recover lycopene (437.5 mg) and β-carotene (36.5 mg) [124]. Based on findings by Inayat et al. [97] at the European level, the estimated economic feasibility of establishing as many as 56 biorefinery facilities exists based on market values of EUR 40,000/kg and EUR 4000/kg for lycopene and β-carotene, respectively. Careful consideration should also be given when determining payback periods in this context, since many real-world applications have payback periods of anywhere from 3 to 15 years [97].

Bioactive compound production using potato waste biorefineries was also found to be economically viable if limited to a total of 28 facilities throughout Europe, with prices maintained at €300/kg [105]. However, the techno-economic feasibility of these facilities is primarily dependent on market stability, and the impact of production overcapacity is still a major concern. Amorim et al. [125] found that by increasing production rates above four times current production levels, market prices for succinic acid could drop significantly [125], which may impact profitability. Market demand will also play an important role in determining scalability. The demand for certain specialty chemicals could be satisfied by just 5–10 biorefineries, whereas a small number of biorefineries would saturate certain high-value pharmaceutical markets; therefore it is essential to develop additional market opportunities through the use of derivative chemicals, as well as to target larger volume industrial markets (e.g., polymer production), which will provide a means to balance the trade-off between the value of a product and the volumes of product required to satisfy its expected demand [126]. Biorefineries come in many different configurations, and not all of them are economically viable.

An example is a wood-based biorefinery that produces ethylene (0.1 tons), biomethane (130 Nm³), hydrolysis lignin (0.45 tons), and organosolv lignin (0.16 tons), has an operational capacity to process beech wood at 400,000 tons per day, and is currently considered not to be economically feasible given the current market conditions [127]. The economic viability of wood-based biorefineries producing these products will increase with small increases in product prices, especially ethylene [127]. In summary, LCA and techno-economic analysis provide a comprehensive analytical method for assessing both environmental and economic sustainability for food waste valorisation, demonstrating the need to design systems optimally, have aligned markets, and create scalable processes.

7.4. Integration with Sustainable Development Goals (SDGs)

The process of turning food waste into something useful aligns with many UN Sustainable Development Goals (SDGs) because it takes waste and turns it into something useful while helping to solve some environmental and economic problems. With SDG 7 (Affordable and Clean Energy), using food waste to make biogas or biofuels creates renewable energy sources and helps decrease our reliance on fossil fuel sources. An example of this would be in India, where there are decentralised biogas plants that are using leftover food from customers’ kitchens or markets to turn into methane gas used for cooking or generating electricity, contributing to a cleaner and more reliable energy system. Food waste valorisation is very important related to SDG 9 (Industry, Innovation and Infrastructure) in that it encourages the development of advanced biorefineries and sustainable industrial processes. One example of this would be the production of biodegradable plastics, such as polylactic acid, from lactic acid derived from food waste by NatureWorks LLC, which illustrates how innovative solutions can take a low-value waste product and create high-value industrial products [128].

In relation to this, utilisation of food waste contributes directly to satisfying SDG 12, which states the need for responsible use of resources and minimisation of waste created per consumption and production. For example, agricultural/industrial by-products such as discarded fruit and vegetable material can be converted into pectin, organic acids, and antioxidants, which can then be used in the production of food, pharmaceuticals, and packaging, thereby decreasing the need for virgin material [129]. In addition, greenhouse gas emission reduction related to SDG 13 can occur through the diversion of food waste away from landfills into processes designed to convert the waste in a controlled manner. Composting and anaerobic digestion reduce methane emissions and produce biofertilizers, leading to increased carbon storage in soil. Many large-scale composting programs and biogas systems around the world have resulted in significant emissions reductions while also generating renewable sources of energy and improving soil fertility [130]. Food waste valorisation contributes to achieving the Sustainable Development Goals (SDGs) indirectly by addressing SDG 6 (Clean Water and Sanitation) through reducing leachate from landfills and the pollution of water bodies, and SDG 2 (Zero Hunger) through improving food system productivity as a whole. Food waste valorisation has been integrated into a number of national sustainability strategies in several different countries. The development of the European Union’s Circular Economy Action Plan expressly includes reducing the amount of organic waste that gets sent to landfill and encouraging the reuse of all forms of organic waste, while India’s Swachh Bharat Mission and National Bioenergy Mission promote waste-to-energy initiatives.

7.5. Global Certification Frameworks and Policy Instruments for Industrial Deployment

The commercialisation of chemicals and products made from food waste requires not only technological innovation but also systems of certification that comply with economic incentives and regulatory frameworks. International standards provide criteria for the quality of product, environmental performance and market acceptance, which help to reduce investor and stakeholder risk. There are a number of certification systems in place globally that guide the commercialisation of bio-based products. The EN 13432 standard in Europe establishes a set of minimum criteria for evaluating compostable packaging materials, while the ISO 17088 standard establishes globally accepted criteria for evaluating biodegradable plastics [116]. Similarly, ASTM D6400 is the standard used by many in North America to evaluate industrially compostable materials. The ISCC PLUS and RSB provide additional sustainability certification systems that support supply chain transparency and traceability of renewable materials. Bio-based product labelling programs also enhance consumer awareness and trust, assisting in establishing a foothold in the market for these products. For example, the USDA BioPreferred^® program establishes a certification system for a product based on the amount of renewable carbon in it; certification marks such as OK Compost and the Seedling label provide verification that a product will meet industrial compostability standards. Together, these labelling systems enable producers to distinguish between sustainable products vs. traditional petrochemical alternatives and increase their market competitiveness internationally [123]. Another major force influencing industrial implementation is economic policy instruments. For example, carbon-pricing systems such as the European Union Emissions Trading System (EU ETS) and the Carbon Border Adjustment Mechanism (CBAM) increase the relative costs of fossil-fuel-intensive production processes and enhance the competitiveness of renewable alternatives. Similarly, renewable fuel standards, feed-in tariffs, investment tax credits, and green public procurement policies provide stable market demand for bioproducts and reduce the financial risk for companies undertaking large-scale investments in biorefineries.

The Sustainable Alternative Towards Affordable Transportation (SATAT) initiative in India is an example of how policies can drive the use of compressed biogas made from farm and food waste by having guaranteed purchasing options and providing financial support. Other countries with similar types of support include Brazil, the US, and the EU, where many companies have invested in creating second-generation biofuels and bio-based chemicals through the provision of a long-term market for their products. Through the implementation of Extended Producer Responsibility (EPR) regulations, companies can encourage the use of biodegradable materials and circular production methods by assigning manufacturers liability for managing products after they are sold [128]. These types of programs stimulate interest in new bio-based packaging solutions and increase the use of compostable polymers created from waste produced by the food processing industry. For the successful implementation of bio-based products within an industrial setting, technological innovation must be linked to harmonisation of certification standards, transparent labelling systems, a carbon pricing program, and targeted financial incentives. A well-coordinated policy framework on an international basis can greatly reduce the risk of commercialisation, increase investor confidence and help move from pilot projects to commercially viable industrial biorefineries. The major policy instruments, certification frameworks, and market mechanisms that facilitate the industrial implementation of food waste valorisation technologies are summarised in Figure 4.

8. Techno-Economic Analysis, Life-Cycle Assessment, and Policy Perspectives

In order to achieve a successful transfer of technologies used for food processing waste (FPW) valorisation from laboratory research into commercial production, it requires more than just efficient conversion; it also requires (i) economic viability, (ii) ecological sustainability, and (iii) appropriate policy support frameworks in place. There are numerous literature examples showing how food waste can be used as a renewable feedstock to produce platform chemicals; commercial applications of these technologies, however, continue to face challenges stemming from (i) variability of feedstock; (ii) complex supply chains; (iii) expensive downstream processing costs; and (iv) uncertainty regarding market needs. The use of integrated techno-economic analyses (TEAs) and life cycle assessments (LCAs) will allow for the assessment of the long-term commercial viability and sustainability of food waste biorefineries.

8.1. Production Cost, Economic Feasibility, and Scalability Challenges

Food-Waste Valorisation systems validate their economic feasibility based on several interdependent components: The availability of feedstocks; the efficiency of system conversions; the requirements for the pretreatment of the organic feedstock prior to conversion; the costs associated with downstream processing; and the market price of biochemical products. In contrast to fossil-based resources, “The wide geographical dispersion and compositional heterogeneity” of food-waste resources result in “significant” additional costs associated with the collection, transport, sorting, and storage of food-waste feedstocks. There are considerable variances in the organic materials found in food waste, such as water content, make-up of organic materials, and levels of contamination, which will require the use of flexible processing systems and more advanced pretreatment technologies and therefore increase operating costs. In addition, while most lignocellulosic food residues require some form of pretreatment for conversion to bioethanol, they can require a significant amount of energy in order to process the food waste into a form suitable for conversion. Further, the downstream separation/purification steps utilised for producing bioethanol, organic acids, volatile fatty acids, and platform chemicals represent a significant contribution towards the total manufacturing costs of these products. The methods of recovering bioethanol, organic acids, volatile fatty acids, and platform chemicals through distillation, membrane separation, solvent extraction, and chromatographic separations will significantly impact how much these processes economically and energetically translate into the complete conversion of food-waste feedstock into useful chemicals. Integrated biorefineries provide a potentially profitable strategy for ultimately having multiple by-products co-produced at one time to earn multiple revenue sources. For instance, by producing bioethanol, biogas, speciality chemicals, and lignin-based products concurrently, a diversified revenue source is created while maximising resource utilisation and minimising waste [110]. Techno-economic studies also indicate that by integrating electricity production, biogas recovery, and speciality chemicals with second-generation biorefineries, the selling price of bioethanol will decrease and thus improve profitability [1]. However, substantial capital investment requirements for infrastructure, advanced processing equipment, and commercialisation are significant barriers, particularly in developing countries where there are limited sources of financial capital [119].

8.2. Feedstock Logistics and Supply-Chain Management

Industrial sustainability relies heavily on effective feedstock logistics. Due to the highly perishable nature of food waste with fast physicochemical decay, coordinated systems for properly collecting, segregating, transporting and storing food waste are needed to preserve feedstock quality and establish process stability [131]. Decentralised biorefineries located close to food-processing plants and urban centres that generate food waste help reduce transportation distances, logistics costs, and emissions of greenhouse gases from long-distance transportation of materials to the biorefineries [132]. The experiences of other countries around the world illustrate the importance of good supply chain design. Germany boasts one of the most efficient organic waste management systems, with over 9000 biogas plants providing renewable electricity, food-processing residue-based heating, and biofertilizers from organic waste [133]. Germany’s extensive source separation system, along with its supportive policy environment, has contributed to the deployment of these plants while reducing dependency on landfills and greenhouse gas emissions. Likewise, Sweden collects municipal food waste for conversion into biogas for use as transportation fuel. This effort continues to support the production of renewable energy and advances Sweden’s national climate goals [134]. Many developing nations still suffer from difficulties such as inadequate infrastructure, poor source separation practices, and a lack of organised waste management systems. New capital investments for decentralised processing facilities and investments in education, Internet of Things (IOT) monitoring and optimising systems can greatly improve supply chain efficiency, decrease costs to operate, and reduce environmental impacts from transporting and managing food waste [132].

8.3. Market Value, Product Diversification, and Industrial Competitiveness

The extent to which food waste is used to manufacture platform chemicals is significantly influenced by the range of products produced and the capacity to utilise higher-value co-products. A biorefinery that uses a circular economy should be able to produce both fuel (biofuels) and low-cost, biodegradable materials (biodegradable polymers) along with additional products like vitamins and supplements (nutraceuticals), mineral soil amendments (fertilisers), and speciality chemicals, enabling a biorefinery to generate value from multiple channels rather than just the biologically derived commodities resulting in economic diversity and increasing the economic stability of the biorefinery. The ability to convert residues from, e.g., lignin, digestates, and fermentation byproducts into energy carriers, organic soil amendments (e.g., compost), and non-fossil fuel-derived, chemical intermediates and products will continue to provide improvements in the efficiency and profitability of biorefinery operations [110]. The results from existing biorefineries around the world provide concrete examples of the economic potential of diversified biorefinery systems. For example, Novamont has successfully commercialised biodegradable (compostable) materials under their Mater-Bi brand from renewable agricultural and food-derived feedstocks for use in sustainable packaging applications [89]. The company’s successful commercial production of biodegradable plastics reinforces the financial viability of producing diversified, bio-based products, as well as highlighting the global market demand for new sustainable alternatives to conventional (non-renewable) packaging solutions. This circular production method shows how creating diverse product portfolios helps companies increase market value while also decreasing their reliance on traditional petroleum-based resources. In the same manner, Genomatica has developed the microbial manufacturing method for producing bio-based 1,4-butanediol (BDO) using renewable feedstock, highlighting how the use of metabolic engineering and processing improvements increases the industrial competitiveness of bio-based BDO compared to fossil fuel processes [107]. Important partnerships with major chemical manufacturers have enabled the expanded use of bio-based 1,4 BDO production at the industrial level, which demonstrates the competitiveness of renewable production pathways for the global chemical market.

Improvements in microbial engineering, process intensification, integrated product recovery and more have also reduced costs for manufacturing bio-based chemicals and increased efficiency in converting raw materials to value-added products, thereby reducing the cost differential between the bio-based and the conventional chemical industry [131]. Despite the improvements noted above, the acceptance of bio-based chemicals in the marketplace, obtaining regulatory approval and the continuing volatility in the prices of traditional fossil-based chemicals will create significant obstacles for the long-term commercial success of the bio-based chemical industry, thereby requiring continued innovation in technology and supportive policy measures to facilitate success [119].

8.4. Energy Balance, Greenhouse-Gas Reduction, and Life-Cycle Assessment

The life-cycle assessment (LCA) process can be described as a structured way to look at the environmental sustainability of food-waste valorisation pathways. When conducting an LCA, typical boundaries will include everything that is needed for feedstock collection, transportation, pretreatment, conversion processes, downstream purification, product use and end of life. Cradle to gate LCA’s will only look at the environmental impacts of producing products from the various point sources of feedstocks. In contrast, cradle to grave LCA’s will look at not only producing products but also at how much product was consumed, how and when the product will be disposed of [132]. The environmental benefits of food-waste biorefineries, or other means of valorising or converting food waste into value, are derived primarily from reducing landfill disposal of food waste, reducing methane emissions from food waste blamed for climate change and reducing the use of fossil resources. Anaerobic digestion, biogas production and integrated biorefinery operations help to reduce greenhouse gases by capturing energy and recycling carbon through circular production methods [114,133,134]. Bio-based alternative chemicals used instead of petroleum-derived chemicals also help to lower carbon footprints while supporting broader climate and sustainability initiatives [111]. Germany’s biogas infrastructure illustrates the environmental benefits of the biomass diversion of organic waste from landfills into anaerobic-digestion plants. By eliminating methane emissions and producing renewable energy and bio-fertiliser from those inputs, this process has improved both the environmental and economic performance indicators in Germany [135]. In Sweden, the municipal-biogas program takes segregated food waste and turns it into biomethane through the use of anaerobic digestion for public-transportation systems and district energy systems, thus significantly supporting Sweden’s decarbonization agenda while simultaneously reducing the country’s dependence on fossil fuels [136,137]. These real-world examples highlight the necessity of taking all transportation distances, energy inputs, variability of feedstocks, and the requirements of downstream processes into consideration when determining the sustainability of food-waste biorefineries at an industrial scale pursuant to their Life Cycle Analysis (LCA) boundaries [138]. However, the potential benefits associated with the environment cannot be assumed to occur naturally. Heavy use of energy for pre-treatment techniques, along with fluid chemicals used during the chemical pre-treatment and fluid chemicals used in any subsequent purification operation, can reduce or eliminate such benefits unless process optimisation in terms of integrating and recovering energy from these processes has been properly performed. Thus, the combination of techno-economic analysis (TEA) and life-cycle assessment (LCA) of process configuration is critical for finding those configurations that maximise economic return while minimising environmental impact. Such analyses will support multi-objective decision-making as required by sustainable production in terms of energy balances, carbon efficiencies, and greenhouse gas mitigation potentials [89,113].

8.5. Policy Incentives and Regulatory Frameworks

The role of government policy and regulatory frameworks is critical in accelerating the commercialisation of chemicals produced from food waste. For example, the European Union’s Circular Economy Action Plan encourages resource efficiency, waste reduction, and the establishment of bio-based industries by providing financial support and regulatory incentives [111]. The National Bioenergy Mission in India, on the other hand, encourages investment in biogas facilities, bioethanol production, and waste-to-energy technologies that address both waste management issues and energy security objectives [136,137]. For instance, the Ministry of New and Renewable Energy (MNRE) has provided support for decentralised biogas installations through initiatives like the Gobar-Dhan programme and the National Bioenergy Programme in order to promote sustainable waste management and ensure energy security in rural areas [139,140]. Economic instruments such as carbon credits, tax incentives, PVCs and FITs, or waste-to-energy/energy recovery technologies incentivise the production of renewable energy via greenhouse gas emissions reductions and as such are critical elements in supporting project economics [140]. Regulators, including the EFSA and EPA, work to define quality and safety standards to encourage consumer confidence, improve the acceptance of biobased materials within industrial, agricultural, and food markets by creating a level playing field for bio-based companies [139]. The application of sustainable practices in industry also illustrates how supportive governmental policies impact the commercialisation of new products. Veolia has constructed a series of anaerobic digester facilities in both Europe and Asia that demonstrate how an integrated approach to waste management can create biogas (energy recovery) and nutrient-rich fertilisers (resource recycling) while also mitigating greenhouse gases [140]. The success of the above cases indicates that, through the implementation of sustainable technology and business practices, implementation at the industrial level, with a supportive regulatory framework and stable feedstock supply chain, can have a positive impact on both the economic performance of production and the environmental sustainability of those products. Overall, these initiatives indicate that supportive regulatory frameworks, consistent availability of feedstock supply chains and demand for these products all contribute to the successful commercialisation of newly developed products within the circular bio-economy. These improvements notwithstanding, challenges still exist in regards of harmonization of national policies; too many lengthy levels of review procedures, and often inconsistent implementation of such procedures between differing jurisdictions. Effective solutions need long-term regulatory stability as well as streamlined review mechanisms to drive toward consistent international sustainability standards to encourage investors and efficiently deploy the Circular Renewable Food Waste Biorefinery [114,139]. The key safety assessment procedures and regulatory pathways governing food waste-derived products for food, pharmaceutical, and agricultural applications are illustrated in Figure 5.

9. Challenges and Future Research Directions

Even though there has been significant progress made in converting food processing waste into chemicals, there are still many technological, scientific, and structural obstacles that make it difficult for companies to implement these processes on a wider basis. Improving feedstock, bioprocessing, digital technology, and collaborative innovative frameworks will require an integrated approach to solving the aforementioned obstacles. This section provides a critical assessment of the bottlenecks in this area and suggests some of the future research directions needed to advance this area towards its commercialisation maturity.

9.1. Feedstock Heterogeneity and Process Optimisation

Challenges associated with Food Waste valorisation are attributable to the highly heterogeneous nature of feedstocks produced from Food Waste Processing Operations. There is considerable variability in the Chemical composition of Food Processed Wastes based on the type of Food, the seasonality of the Food, the method of Food Processing, and its storage conditions. The variability in the composition of carbohydrates, lipids, proteins and lignocellulosic materials has a significant impact on the ability to convert this type of waste into products, thus impacting the yield and the stability of these processes [140]. For example, Fruit/Vegetable Waste is typically composed of Simple Carbohydrates and is moist, making it suitable for the fermentation process; however, Lignocellulosic Residues such as cereal bran and peels, require significant processing prior to being suitable for fermentation because they must undergo extensive preparation to free up fermentable sugars. Conversely, food processors could produce biodiesel from Food Waste containing a high level of lipids, and thus, this type of waste may not be suitable for fermentation. As such, there must be flexible and adaptable processing systems to accommodate these types of feedstocks [137]. To overcome the problems mentioned, the application of Advanced Preprocessing Technologies is necessary. Mechanical, Thermal, Chemical, and Biological Pretreatments are being developed and/or optimised to improve the accessibility of substrates and increase the efficiency of conversion of substrate to products. For example, there are numerous methods of breaking down lignocellulosic structures (i.e., steam explosion, dilute acid hydrolysis) that are commonly used in the industry despite their high energy input and the potential for creating inhibitors. Real-time overseeing and controlling systems are currently one of the most important methods to monitor the changes in feedstock variability. Many different types of sensor and analytic systems have been integrated together (i.e., near-infrared spectroscopy) to help facilitate the rapid identification of the composition of the feedstock, thereby allowing the easy modification of the processing parameters for the optimal operation of the bioreactor. This allows for greater stability in the process, as well as better consistency in the product produced. Ongoing research needs to focus on developing bioprocessing technologies that are flexible with regard to feedstock, as well as the development of low-energy associated pretreatment technologies to minimize the amount of chemicals used and the amount of environmental impact. The implementation of standardization protocols for the quality and classification of feedstocks may also contribute to a more efficient industrial operation. The strategic directions and key technological priorities required to accelerate food waste valorisation toward industrial-scale circular bioeconomy systems are summarized in Figure 6.

9.2. Advances in Synthetic Biology and Metabolic Engineering

Synthetic biology and metabolic engineering have transformed how companies make platform chemicals by using renewable feedstocks. These engineered microbes are designed to use substrates better, provide better product yields, and make new compounds. Many of the microbes used as hosts for metabolic engineering are the Gram-negative, non-spore-forming bacterium Escherichia coli; the eukaryotic yeast Saccharomyces cerevisiae; and the Gram-positive actinomycete Corynebacterium glutamicum. By genetically modifying these organisms, they are able to efficiently convert complex food waste-derived sugars into valuable compounds [138]. For example, engineered E. coli have been designed to produce high yields of succinic acid by optimising the metabolic pathways and minimising by-product formation [135]. Advanced engineering of yeasts has also enabled the efficient production of bioethanol and higher alcohols, including butanol. Synthetic biology approaches utilise molecular tools such as CRISPR-Cas for rapid and accurate genome modifications to create strains, allowing the introduction of heterologous pathways, deletion of competing pathways and optimisation of regulation (e.g., protein expression levels and/or transcriptional regulators). Industrially, engineered microbes have many applications being developed. One example of a company that has commercialized the production of chemicals using engineered microbes is Genomatica and they produce bio-based chemicals, including 1,4-butanediol (BDO). This is a successful verification of the synthetic biology capabilities to create new manufacturing processes, because these processes have the ability to replace traditional petrochemical processes [140]. Even though there are successful examples of engineers creating microbes being used for the manufacturing of chemicals, other factors still present challenges. Common challenges include maintaining engineered organisms at industrial operational efficiencies through stresses (e.g., high concentrations of substrates, inhibiting substances, and varying environmental conditions), as well as regulatory approvals and public perceptions of genetically modified organisms (GMOs) [141]. To continue research in this area, priority should be placed on the development of robust and resilient microbial strains that can utilise more than one substrate and implement systems biology strategies for improving and/or optimising metabolic networks. To achieve this goal, combining the use of synthetic biology with process engineering will play a key role in developing economically viable and scalable production systems.

9.3. Digitalisation and Smart Biorefineries

Digitalisation of biorefinery functional processes provides a revolutionary method to improve performance and increase efficiency, reliability, and scale. The use of artificial intelligence (AI), machine learning (ML), and process control systems enables the development of a new class of biorefinery facilities called Smart Biorefineries; these systems will augment real-time production processes. Machine learning (ML) and artificial intelligence (AI)-based algorithms can identify patterns within the massive amount of bioprocess data being generated by advanced bioprocessing systems. For example, predictive models using AI and ML could enable optimum fermentation parameters, such as pH, temperature and nutrient concentrations, thus improving the yield of the produced bio-chemicals and reducing the cost of production [140,141]. Smart sensors and IoT (Internet of Things) technologies will allow for real-time monitoring of process variables (substrate concentration level, microbial cell activity and product formation), allowing for both real-time decision making and automated processes with limited to no manual interference and reduced variability in process performance [89]. Digital twinning will be another example of a powerful technology enabling process optimisation; digital twins will be virtual replicas of physical biorefinery systems, and they can be used for testing the impact of operating under different sets of conditions to determine the most appropriate operational settings within a biorefinery system. The industrial sectors are progressively utilising digitalisation as a means of improving productivity as well as sustainability. Digital tools can also be utilised in food waste Valorisation and within the supply chain management field for efficient collection, tracking, and allocation of resources. Challenges remain, however, in the form of continued difficulties with data integration, system complexity and high implementation costs; thus, the creation of standardised data platforms and user-friendly interfaces will be necessary for mass adoption of such technologies to occur. Further research will be necessary to focus on the integration of digital technologies into bioprocess engineering, ultimately creating fully automated and adaptable biorefinery systems.

9.4. Need for Interdisciplinary and Industry–Academia Collaboration

To successfully commercialise technologies that turn food waste into a resource will require collaboration among academics, industry representatives and policy makers. Academics have made great strides in understanding the fundamental processes involved and creating innovative new technologies; however, there are many barriers to transferring this knowledge into industrial applications. In particular, the disparity that exists between research at the laboratory scale and at the industrial scale presents many challenges for researchers trying to develop new applications for their findings. Laboratory-based analysis of processes can yield excellent results when done under controlled conditions; however, as those processes are scaled up, they may exhibit significant differences in mass transfer performance, process parametric, economic constraints, etc. Collaboration between academia and industry may be beneficial by aligning the research goals of both groups with those that are practical or applicable. Public–private partnerships (PPPs) can be an extremely important tool for speeding up the development and commercialisation of new technology by allowing for the sharing of funding, infrastructure, and technical expertise in order to move from research to a commercial market. This can be evidenced by any number of joint ventures formed between biotechnology companies and university research institutions that resulted in the successful development of biorefinery technologies and the commercialization of bio-based products [141]. Food waste valorisation requires interdisciplinary collaboration across many fields, such as microbiology, chemical engineering, environmental science, economics, and policy studies. By using knowledge from all of these disciplines, it will be possible to develop more comprehensive and sustainable solutions. The ability to collaborate among researchers and other technical experts is further enhanced when governments provide support through funding initiatives, innovation centres, and policy incentives targeted at technology development. Opportunities for global collaboration will also facilitate knowledge sharing and capacity building in developing countries. Future efforts to build innovative ecosystems will encourage collaboration across sectors, create technology transfer processes, and provide the opportunity for capacity building and skill development. Ultimately, these types of initiatives will help provide the bridge between research and the application of the technology in industry.

10. Conclusions

Food processing waste is an abundant, renewable resource for producing biofuels, platform chemicals, bioplastics, and other high-value products in a circular bioeconomy. Technological advances in biological, thermochemical, and integrated biorefinery processes have confirmed that converting food processing waste into useful products is both technically feasible and environmentally beneficial, as well as reducing greenhouse gas emissions, landfill disposal, and reliance on fossil resources. However, the large-scale use of food processing waste has not yet been realised due to challenges related to feedstock heterogeneity, economic viability, supply chain logistics, and infrastructure. Therefore, future research should focus on feedstock standardisation, process intensification, advanced downstream recovery, digital monitoring, and synthetic biology to enhance conversion efficiencies and decrease production costs. Additionally, attention should be paid to developing harmonised sustainability standards, safety regulations, and supportive policy mechanisms to facilitate commercialisation. In conclusion, integrating food processing waste valorisation into circular bioeconomy strategies will continue to provide a viable pathway for achieving sustainable industrial development, resource efficiency, and long-term environmental resilience.