Sugarcane Industry By-Products: A Decade of Research Using Biotechnological Approaches

Abstract

The sugarcane industry plays a crucial economic role worldwide, with sucrose and ethanol as its main products. However, its processing generates large volumes of by-products—such as bagasse, molasses, vinasse, and straw—that contain valuable components for biotechnological valorization. This review integrates approximately 100 original research articles published in JCR-indexed journals between 2015 and 2025, of which over 50% focus specifically on sugarcane-derived agroindustrial residues. The biotechnological approaches discussed include submerged fermentation, solid-state fermentation, enzymatic biocatalysis, and anaerobic digestion, highlighting their potential for the production of biofuels, enzymes, and high-value bioproducts. In addition to identifying current advances, this review addresses key technical challenges such as (i) the need for efficient pretreatment to release fermentable sugars from lignocellulosic biomass; (ii) the compositional variability of by-products like vinasse and molasses; (iii) the generation of metabolic inhibitors—such as furfural and hydroxymethylfurfural—during thermochemical processes; and (iv) the high costs related to inputs like hydrolytic enzymes. Special attention is given to detoxification strategies for inhibitory compounds and to the integration of multifunctional processes to improve overall system efficiency. The final section outlines emerging trends (2024–2025) such as the use of CRISPR-engineered microbial consortia, advanced pretreatments, and immobilization systems to enhance the productivity and sustainability of bioprocesses. In conclusion, the valorization of sugarcane by-products through biotechnology not only contributes to waste reduction but also supports circular economy principles and the development of sustainable production models.

1. Introduction

Sugarcane (Saccharum officinarum) is one of the world’s most important crops, valued both for its traditional role in sugar production and its expanding use in the generation of bioproducts and biofuels. Grown primarily in tropical and subtropical regions, this C4 plant (initiation of CO₂ capture with a four-carbon precursor) is notable for its high photosynthetic efficiency and its ability to synthesize and store sucrose in its stems. With an annual production of approximately 2 billion tons, sugarcane not only drives rural and agroindustrial economies but also presents opportunities for energy diversification and sustainable development [1,2].

The primary purpose of sugarcane cultivation has traditionally been sucrose production, the basis of the sugar industry. However, its biomass composition—consisting of 40–50% cellulose, 25–30% hemicellulose, and 15–20% lignin—opens new possibilities within the biorefinery model. This enables the production of high-value derivatives such as ethanol, succinic acid, xylitol, lactic acid, and other compounds that support the growth of the bioeconomy [3,4].

In this context, the concept of the integrated biorefinery has gained growing relevance as a model for sustainable biomass utilization. An integrated biorefinery is a facility that converts renewable biomass—including sugarcane by-products—into a broad range of bio-based products such as biofuels, chemicals, and materials through a combination of thermochemical, biochemical, and catalytic processes [5,6]. These systems aim to maximize the value extracted from all biomass components (cellulose, hemicellulose, and lignin), while minimizing waste and promoting circularity. Integrated biorefineries are also characterized by their alignment with sustainability principles, including resource efficiency, water and energy savings, and the potential for carbon neutrality.

The sugarcane processing industry generates large amounts of by-products at various stages of production, including leaves and tops (straw), bagasse, molasses, and vinasse. These residues differ in chemical composition and are produced in varying proportions. Despite their considerable potential, they pose significant challenges for effective management and valorization. Sugarcane bagasse, a fibrous residue left after juice extraction, is commonly used for energy generation, paper production, and animal feed. However, the complexity of its polymeric structure hinders its complete conversion into monomeric sugars [1,4]. Similarly, other waste products, such as ash from bagasse combustion and vinasse from the alcoholic fermentation process, require specific management strategies. Ash contains high silica levels and a crystalline structure that limits its reactivity, while vinasse, often used in fertigation, can lead to soil salinization and aquifer contamination, as well as promote pest proliferation [7,8].

These challenges within the sugarcane agroindustry underscore the need to explore new strategies for the integrated and sustainable management of waste. Optimizing transformation processes and implementing innovative technologies for by-product valorization not only help mitigate environmental impacts but also improve the industry’s efficiency and competitiveness, reinforcing sugarcane’s role as a key pillar in the transition toward more sustainable production systems.

In recent years, several comprehensive review articles have made valuable contributions to the understanding of sugarcane industry by-product valorization from various angles. For example, Sarker et al. (2017) [9] examined technological developments in the conversion of bagasse and pressmud, highlighting challenges related to biomass recalcitrance and the need for improved microbial strains and pretreatment strategies. Ungureanu et al. (2022) [10] provided a broad overview of both solid and liquid residues generated during sugarcane processing, focusing on their physicochemical properties and valorization pathways within the framework of sustainable development. Antunes et al. (2022) [11] presented a more targeted review on lignin extracted from bagasse and straw, outlining its potential applications in materials science and cosmetics. Iwuozor et al. (2022) [12] addressed the transformation of several sugar industry by-products—such as bagasse, molasses, and pressmud—into energy and chemicals, while underscoring key technological and economic barriers to implementation.

More recently, Bano et al. (2025) [13] provided a detailed review of innovative approaches for the safe and sustainable management of solid wastes from sugar mills and refineries, including the valorization of molasses, pressmud, bagasse, and incinerated spent wash ash. The study emphasized applications across agriculture, energy, construction, and bioconversion sectors, while also discussing environmental risks and emerging technologies such as zero liquid discharge (ZLD) systems. Similarly, Kamboj et al. (2024) [14] focused on the sustainable utilization of sugarcane bagasse (SCB), underlining its potential in the production of biofuels, industrial enzymes, bioplastics, and bioactive compounds. This review also highlighted recent advances in pretreatment technologies and policy frameworks that support SCB-based bioenergy initiatives. Additionally, Dotaniya et al. (2016) [15] examined the agronomic potential of sugarcane by-products like pressmud, bagasse, and molasses, particularly for improving soil health and crop productivity. Their analysis emphasized the nutrient value of these residues and the effectiveness of biocomposting strategies for creating organic fertilizers. Collectively, these reviews reflect the growing body of interdisciplinary research aimed at optimizing the valorization of sugarcane by-products for environmental, agricultural, and industrial applications.

While acknowledging the strength and significance of these prior contributions, the present review aims to serve as a complementary synthesis, focusing specifically on biotechnological approaches reported in original research studies published over the past decade (2015–2025). Our objective is to provide a resource particularly useful for early-career researchers and students, by mapping out concrete examples of how sugarcane by-products—such as bagasse, vinasse, straw, and molasses—have been valorized through biotechnological tools. Through the analysis of experimental studies, we highlight common strategies (e.g., solid-state and submerged fermentation, anaerobic digestion, biocatalysis), the types of microorganisms used, the products obtained, and key operational challenges. In doing so, this review seeks to offer a practice-oriented perspective on the current state of the field and the opportunities ahead for building more sustainable bioprocessing systems.

2. Methodology

A structured literature search was conducted using the SCOPUS database to identify relevant peer-reviewed articles on the valorization and applications of sugarcane industry by-products. The search included combinations (using Boolean operators) of the following keywords: “Sugarcane bagasse”, “Cane bagasse”, “Bagasse waste”, “Sugarcane fiber”, “Sugarcane pulp”, “Bagasse biomass”, “Sugarcane stalk residue”, “Sugarcane fibrous residue”, “Molasses”, “Sugarcane molasses”, “Alcohol industry waste”, “Fermentation waste”, “Molasses spent wash”, “Vinasse”, “Ethanol stillage”, “Ethanol fermentation by-product”, “Fermentation broth waste”, and “Sugarcane straw”. The search was limited to original research articles published between 2015 and 2025 in journals indexed in the Journal Citation Reports (JCR). To ensure topic relevance, only articles classified under the subject areas of Agricultural and Biological Sciences, Biochemistry, Genetics and Molecular Biology, and Immunology and Microbiology were considered. Titles and abstracts of the identified studies were screened to assess their relevance. Articles were selected based on their focus on the utilization or biotechnological potential of sugarcane by-products. Non-original works such as reviews, conference papers, and editorials were excluded.

In addition, in the section entitled “Biotechnological tools for the valorization of agroindustrial by-products”, a selection of foundational or “classic” articles was included to provide conceptual background. These articles were not subject to the same inclusion criteria as the rest of the review, as they were selected based on their significance in the development and understanding of key biotechnological approaches.

3. Biotechnological Tools for the Valorization of Agroindustrial By-Products

3.1. Solid State Fermentation

Solid-state fermentation (SSF) is a fermentative process that occurs on solid substrates in the absence or near absence of free water, relying on a substrate that retains enough moisture to support microbial growth and metabolism. This technique emulates the natural conditions under which many microorganisms grow on moist solids. Additionally, SSF presents significant opportunities for agroindustrial waste processing, as its lower energy requirements and minimal effluent generation help mitigate the challenges associated with solid waste disposal [16].

The potential of SSF for waste valorization is vast. According to Chilakamarry et al. (2022) [17], by-products from nut processing, such as shells, fiber, and pith, can be utilized for the production of biopulp, biochar, and activated carbon. Similarly, residues from cereal and spice processing, including husk, hull chaff, and stalks, have been used for enzyme production and activated carbon synthesis. In the wood industry (e.g., pulp and sawdust) and animal by-product processing (e.g., skin, hides, fleshing waste, fats, horns, bones, liver, and intestines), SSF enables the production of enzymes, animal feed, adhesives, surfactants, lubricants, and filtration materials [17].

3.2. Anaerobic Digestion

Anaerobic digestion is a biological process in which microorganisms break down and stabilize organic matter in the absence of oxygen, producing biogas (a renewable mixture of carbon dioxide and methane) along with microbial biomass [18]. This method not only helps reduce pollution from agricultural and industrial activities but also lessens dependence on fossil fuels. Its advantages include low sludge production, reduced energy consumption, and the potential for energy recovery. However, maintaining operational stability remains a key challenge for its large-scale commercial implementation [18].

A wide range of waste materials can be valorized through anaerobic digestion. According to Mata-Alvares et al. (2000) [19] and Ward et al. (2008) [20], materials such as slaughterhouse and catering waste, poultry mortality, the organic fraction of municipal solid waste (OFMSW), sewage sludge, mycelium waste, coffee pulp, fish farming sludge, and food waste can all be processed. Additionally, agricultural and plant by-products, including winter rye straw, oilseed rape, beans, corn silage, winter wheat, summer barley, and beet leaves, can serve as viable substrates for anaerobic digestion. This variety highlights the versatility of anaerobic digestion in converting diverse waste materials into energy sources and biomass.

3.3. Biocatalysis

Biocatalysis is defined as a process in which a precursor molecule is transformed by the action of enzymes and/or whole cells, either free or immobilized. It includes both biotransformation and enzymatic catalysis [21]. This approach enables the execution of one or more simultaneous reactions that differ from conventional chemical processes. These differences derive from factors such as enzymatic kinetics, protein stability under specific conditions, and the characteristics of catalysts derived from their role in cell physiology—such as growth, enzyme activity induction, or the use of metabolic pathways for multistep reactions [22].

Enzymes are the definitive example of sustainable catalysts: they are biocompatible, biodegradable, and derived from renewable resources. Enzymatic processes are carried out under milder conditions compared to chemical catalysis, utilizing ambient temperature, atmospheric pressure, and physiological pH, with water as the medium. This enables high reaction rates and selectivity. The inherent properties of enzymes often eliminate the need for protecting or activating functional groups, resulting in more economical synthetic routes with fewer steps, less waste, and greater energy efficiency compared to chemical synthesis. As a result, biocatalysis has become a crucial technology for the green and sustainable production of chemicals, pharmaceuticals, flavors, fragrances, and vitamins [23].

In this context, biocatalysis plays a key role in the valorization of lignocellulosic residues through enzymes specialized in the degradation of plant polysaccharides. Fungi, in particular, produce a broad range of enzymes that target polysaccharides, enabling the hydrolysis of cellulose, hemicellulose, and pectin—key components of the plant cell wall. The enzymes, classified into different families based on their structure and function, facilitate the efficient conversion of lignocellulosic biomass into high-value products, such as biofuels, bioplastics, and sustainable chemicals. Thanks to the diversity and specificity of these enzymes, biocatalysis provides an eco-friendly alternative for transforming agroindustrial waste into valuable resources for industries such as food, paper, and bioenergy [24].

3.4. Submerged Fermentation

Submerged fermentation (SmF) is a process in which microorganisms grow and decompose substrates (e.g., carbohydrates) in the presence of abundant free water (liquid medium), under anaerobic or partially anaerobic conditions. This technology is widely used for large-scale ethanol and enzyme production, as it allows for precise monitoring and control of fermentation conditions [25,26]. Overall, fermentation processes are highly versatile for the valorization of agroindustrial waste from various sectors. For example, SmF can be applied to waste from the fishing industry (including canning, filleting, curing, salting, smoking, and processing crustaceans and mollusks), the meat industry (such as slaughtering cattle, pigs, and poultry), the dairy sector (including the production of milk, butter, cream, yogurt, and cheese), winemaking (both white and red wines), and the vegetable industry (involving juice production, fruit and vegetable processing and preservation, oil extraction, and the production of starches and sugars) [27].

This biotechnological toolkit illustrates how the integration of techniques such as SSF, anaerobic digestion, SmF, and biocatalysis can convert agroindustrial waste into valuable resources, supporting sustainable management and driving the circular economy.

3.5. Comparative Economic Aspects of Biotechnological Applications

The economic viability of biotechnological applications plays a central role in the valorization of sugarcane residues, as it determines the feasibility of scaling up laboratory processes into industrial operations. Among the most widely applied biotechnologies are SSF, SmF, anaerobic digestion, and biocatalysis. Each of these presents distinct economic profiles when evaluated in terms of input costs, potential for cost savings, scalability, and environmental value added.

SSF emerges as a particularly attractive alternative due to its ability to use agroindustrial residues as substrates, significantly reducing the cost of raw materials [28]. The process operates with minimal water and energy requirements and does not demand complex infrastructure, making it suitable for low-cost and small-scale operations. Additionally, its simplicity and compatibility with enzyme production have enabled successful industrial-scale applications, especially in countries like Japan. Beyond direct production costs, SSF contributes to environmental and economic sustainability by valorizing waste and minimizing pollution, while also enabling the production of high-value biodegradable compounds such as biosurfactants.

Anaerobic digestion also demonstrates considerable economic potential through the dual benefit of waste treatment and energy generation. The use of readily available organic waste, including agricultural residues such as sugarcane bagasse or vinasse, eliminates feedstock costs and reduces waste disposal expenditures [29]. The biogas produced can be used on-site, further reducing energy expenses. Moreover, the flexibility of anaerobic digestion systems allows for applications at both rural and industrial scales. Economically, the incorporation of trace elements and nanoparticles has been shown to enhance methane yields, improving the overall performance of the process. In this way, anaerobic digestion supports circular economy principles by transforming residual biomass into energy- and nutrient-rich digestate.

In contrast, though widely used in the bioethanol industry, SmF presents a more nuanced economic profile. SmF requires significant water input, strict sterility conditions, and enzymatic hydrolysis when lignocellulosic substrates are involved; factors that can increase operational costs [25]. Nonetheless, its compatibility with continuous operation and capacity to process large volumes make it attractive for large-scale ethanol production. The economic feasibility of SmF improves significantly when low-cost feedstocks like non-edible mohua flowers or sugarcane molasses are used, helping to offset the cost of enzymes and infrastructure. Still, optimization strategies are required to streamline process steps and reduce energy consumption during scale-up.

Biocatalysis, on the other hand, offers a highly efficient and green alternative, particularly in the synthesis of fine chemicals and high-value metabolites. Enzymes used in these processes exhibit remarkable catalytic efficiency and selectivity, reducing the need for downstream purification and by-product treatment [30]. From an economic perspective, the development of enzyme immobilization, co-factor recycling, and recombinant expression systems has significantly reduced operational costs and increased industrial viability. Moreover, biocatalytic systems operate under mild reaction conditions, translating into energy savings and safer working environments. Although the initial cost of enzyme development remains a barrier, recent advances in enzyme engineering and process optimization have made biocatalysis increasingly competitive for large-scale applications.

In summary, each biotechnological approach to sugarcane residue valorization presents unique economic advantages and challenges. SSF and anaerobic digestion stand out for their low input requirements and adaptability to regional and decentralized production models. SmF offers proven scalability in bioethanol production, particularly when using cheap substrates. Meanwhile, biocatalysis provides high-value outcomes and environmental compatibility for more specialized products. Ultimately, the selection of suitable technology will depend on the specific metabolite of interest, local resource availability, and integration into existing industrial infrastructure.

4. Main By-Products of the Sugarcane Industry

4.1. Sugarcane Bagasse

Sugarcane bagasse is a lignocellulosic by-product produced in the sugar industry after extracting juice from sugarcane. Biochemically, it consists primarily of 40–50% cellulose, 20–30% hemicellulose, 20–25% lignin, and 1.5–3% ash, giving it a high energy content [31,32]. Additionally, its composition includes small amounts of trace elements and mineral salts, and its fibrous structure makes it suitable for various industrial applications, such as the production of second-generation bioethanol, bioplastics, and paper [31,33].

This by-product is produced during the milling and extraction of sugarcane juice, with the remaining fiber accounting for approximately 35% of the total weight of processed sugarcane [31]. In terms of production, it is estimated that for every ton of sugarcane processed, about 280 kg of dry bagasse is generated [33]. Brazil and India are the world’s leading sugarcane producers, with Brazil alone producing over 560 million tons of cane during the 2012/2013 harvest, resulting in the generation of around 185 million tons of bagasse [31,32]. For comparison, China produces approximately 5.2 million tons of bagasse annually [34].

Currently, much of the sugarcane bagasse is used as fuel in sugar mills for steam and electricity generation, though its utilization remains limited, leading to challenges in handling and storage [32]. However, in recent years, there has been a growing effort to diversify its use in biorefineries, exploring its conversion into value-added products such as nanocellulose, activated carbon, bioethanol, and other sustainable materials [33,35,36].

4.1.1. Biotechnological Approaches for the Utilization of Sugarcane Bagasse

The utilization of sugarcane bagasse has been approached in various ways. In this study, we have compiled works that employ biotechnological tools such as biocatalysis and different fermentation systems for its use (

Table 1. Biotechnological processes for the valorization of sugarcane bagasse.

Ref.	Product	Application	Process
[33]	Cellulose nanofibrils	Food, pharmaceutical, packaging, film, paper, and nanocomposites	Biocatalysis
[37]	Bioethanol	Biofuel	Biocatalysis and SmF
[38]	Cellulases	Detergent additive	SmF
[39]	Cellulose nanofibrils	High-performance products (electronics)	Biocatalysis
[40]	Pectinases	d-galacturonic acid production	SSF
[41]	Cellulases and xylanases	Enzymatic saccharification	SSF
[42]	Biosurfactants	Food and pharmaceutical industries	SmF
[43]	Ethanol and xylitol	Food and pharmaceutical industries	Biocatalysis and Simultaneous Saccharification and Fermentation
[44]	Xylo-oligosaccharides	Prebiotics	Biocatalysis
[45]	Cellulases and xylanases	Enzymatic saccharification/bioethanol	SSF
[46]	Cellulases and xylanases	Enzymatic saccharification	SSF
[47]	Single-cell oil	Biofuel (biodiesel)	SmF
[48]	Succinic acid	Food, agricultural, and pharmaceutical industries	SmF
[49]	Xylitol	Food industry (sweetener)	SmF
[50]	Cellulose films	Packaging and medicine	Biocatalysis

SmF: Submerged Fermentation; SSF: Solid-State Fermentation.

). In this context, the range of products that can be produced is vast, with proposals including the production of hydrolytic enzymes, cellulose nanofibers, biofuels, acids, sweeteners, oils, and more.

The processes used for the valorization of sugarcane bagasse are diverse, with no clear dominance of any single biotechnological tool. Regarding the applications of the products derived from bagasse, those in the food and pharmaceutical sectors are the most prominent, followed by applications for saccharification and biofuel production.

In some cases, biotechnological tools play a supporting role in the process. For example, Saelee et al. (2016) [33] used xylanases to pretreat sugarcane bagasse fibers, which had already been treated by steam explosion, reducing subsequent processing times and the need for chemical agents. A similar approach was used by Nie et al. (2018) [39], who applied a combined pretreatment of xylanases and an alkaline treatment to remove part of the hemicellulose and convert cellulose I to cellulose II. Likewise, ref. [50] performed a two-step pretreatment (xylanase–alkaline), resulting in an increased crystallinity index and thermal stability in the cellulose fibers, which were then used for reconstructing cellulose films.

In other cases, such as studies by Pereira et al. (2015) [37] and Unrean et al. (2018) [43], multiple biotechnological tools are used; these processes incorporate a biocatalysis stage to saccharify lignocellulosic biomass, followed by SmF with Saccharomyces cerevisiae and Candida tropicalis to produce ethanol and xylitol, respectively. In the case of Unrean et al. (2018) [43], these processes are carried out simultaneously.

On the other hand, authors such as Laderia et al. (2015) [38], Biz et al. (2016) [40], Marques et al. (2018) [41], Morán-Aguilar et al. (2021) [45], and De Cassia Pereira et al. (2015) [46] incorporate sugarcane bagasse as a substrate (or substrate–support) in SmF and SSF systems for the production of hydrolytic enzymes such as cellulases, xylanases, and pectinases. In the studies using SSF, sugarcane bagasse serves as a support for fungal growth, providing nutrients and acting as an inducer (due to the presence of cellulose, xylan, and pectin) for the production of the hydrolytic enzymes.

Sugarcane bagasse holds significant potential for valorization through biotechnological tools, leading to the production of various valuable products across different sectors. Moreover, these strategies can help reduce pollutant emissions from bagasse combustion, contributing to a lower carbon footprint associated with sugarcane cultivation.

4.1.2. Challenges in the Use of Sugarcane Bagasse

Sugarcane bagasse has a complex structure where lignin and hemicellulose act as barriers, preventing easy access to cellulose. This necessitates the implementation of delignification processes using pretreatments to break the bonds between these components in an efficient, cost-effective, and environmentally sustainable way. While methods such as steam explosion have been recognized for their cost-effectiveness in treating agricultural residues (Saelee et al. (2015) [33], De Cassia Pereira et al. (2015) [46]), optimizing these techniques remains a key challenge for their large-scale application.

In the field of biofuel production, using bagasse to produce second-generation ethanol is a promising option, as this residue has an energy content comparable to other sugarcane fractions, such as leaves and stalk tips. However, second-generation technology has not yet reached the maturity of first-generation processes, leading to economic and technological challenges, such as the high investment required for enzymes (cellulases and xylanases) and their limited availability [37,45].

The conversion of bagasse into cellulose nanofibers or xylooligosaccharides (XOS) is also hindered by its structural complexity. In the preparation of nanofibers, for instance, hemicellulose prevents proper enzyme–cellulose interaction, making its removal necessary to enhance the crystallinity and mechanical properties of the resulting composites [39]. For XOS production, the challenge lies in minimizing β-xylosidase activity to prevent excessive xylose formation, thereby ensuring the production of XOS with high purity [43].

On the other hand, when bagasse is used as a substrate in SSF for pectinase production, physical issues such as agglomerate formation, bed shrinkage, and overheating have been reported. These challenges lead to a non-uniform distribution of enzyme activity, complicating the scalability and reproducibility of the process [40]. Additionally, during the pretreatment process (for hemicellulose extraction and lignin degradation), inhibitory compounds such as acetic acid, furfural, hydroxymethylfurfural, and other phenolic compounds can be produced, negatively impacting microbial growth and fermentation efficiency. This necessitates the inclusion of detoxification steps, which in turn increase operating costs [47,49].

Finally, it is important to emphasize that inappropriate bagasse management, such as the open burning of residues, not only misspends its energy potential but also substantially contributes to greenhouse gas emissions [48]. In this context, developing integrated biorefinery strategies that enable the conversion of this by-product into biofuels, chemicals, and high-value materials presents a key opportunity to address the technical, economic, and environmental challenges associated with its use. Figure 1 provides a graphical summary of the potential products and challenges related to the valorization of sugarcane bagasse.

4.2. Sugarcane Molasses

Sugarcane molasses is a by-product of the sugar industry, obtained during the refining process of cane juice, specifically after sugar crystallization. Biochemically, it is characterized by containing approximately 50% (w/w) total sugars, primarily sucrose, glucose, and fructose, along with nitrogenous compounds, vitamins, and around 10% (w/v) inorganic salts. Additionally, it may contain suspended particles and, in some cases, undesirable substances such as 5-hydroxymethylfurfural and excessive levels of metal ions, which can negatively impact productivity in fermentation processes [51,52,53].

Regarding the production stage, sugarcane molasses emerges as the liquid residue left after extracting and crystallizing sugar from cane juice. In other words, once the sugar crystals are separated, the remaining liquid is molasses—a by-product that has gained importance in the fermentation industry due to its low cost and high content of fermentable sugars. It is widely used for the production of bioethanol and other bioproducts [54,55].

In terms of production volumes, it is estimated that processing one ton of sugar generates approximately 0.3 tons of molasses. Globally, around 10 million tons of molasses are produced annually, making it a widely available raw material for various industrial applications. In specific markets, such as China, molasses production is estimated at roughly 3 million tons per year, while in regions like Brazil, where sugarcane is a key resource, this by-product plays a crucial role in ethanol production and other fermentation processes [55,56,57].

4.2.1. Biotechnological Approaches for the Utilization of Sugarcane Molasses

Sugarcane molasses has been utilized through various approaches. In this work, we have compiled studies that employ biotechnological tools, such as biocatalysis and different fermentation systems, for its utilization (

Table 2. Biotechnological processes for the valorization of sugarcane molasses.

Ref.	Product	Application	Process
[58]	Cellulase	Bioethanol synthesis (biofuel)	SmF
[59]	Biosurfactant	Bioremediation	SmF
[60]	PHB	Biodegradable plastics	SmF
[61]	Biosurfactant	Medicine, household products, agriculture, food products, cosmetics, pharmaceuticals, and the petroleum industry	SmF
[62]	Lipids	Biodiesel (biofuel)	Microalgae Cultivation
[63]	Biosurfactant	Immunological and medical applications	SmF
[55]	Bacterial cellulose (or nanocellulose)	Biomedical and pharmaceutical applications	SmF (static)
[64]	Chitin	Drug delivery carriers, antibacterial agents, and food stabilizers	SmF
[65]	PHB	Medical, surgical, and pharmacology (implant material and drug carrier)	SmF
[66]	Methane	Biogas	Anaerobic Digestion
[67]	Alpha-amylase	Saccharification of starchy materials, food, pharmaceutical, detergent, and textile industries.	SmF
[51]	Hyaluronic acid	Medical and cosmetic applications	SmF
[68]	Ectoine	Medicine, cosmetics, and biotechnology	SmF
[69]	Chitinous composites and nanofibers	Composites, cosmetics, pharmaceuticals, and water treatment applications	SSF and SmF
[70]	Ethanol	Biofuel	SmF

SmF: Submerged Fermentation; SSF: Solid-State Fermentation.

). In this context, a wide range of products can be obtained, including biosurfactants, polyhydroxyalkanoates, enzymes, biofuels, and more.

Unlike sugarcane bagasse, molasses is predominantly valorized through SmF. This approach is logical, as molasses is a sugar-rich liquid that can be easily incorporated into liquid culture media. Compared to a solid by-product like sugarcane bagasse, this strategy requires fewer unit operations for its utilization.

From the compiled studies, the most reported applications of products synthesized from molasses include medical, pharmacological, biofuel production, and cosmetic uses. Additionally, some studies focus on addressing environmental issues, such as bioremediation and wastewater treatment. For example, Ma et al. (2017) [62] demonstrated the potential of molasses-based media for simultaneous wastewater treatment and lipid production at low temperatures using Scenedesmus sp., achieving high removal efficiencies for COD, TN, and TP, along with promising lipid yields.

Molasses is widely regarded as a low-cost carbon source, which is why researchers like Ellilä et al. (2017) [58] have proposed its use in the development of an extremely cost-effective cellulase and invertase production process. In their study, a genetically modified strain was employed to reduce the costs of these enzymes, which are essential for biorefineries. Similarly, Simair et al. (2017) [67] optimized α-amylase production using Bacillus sp. and various carbon sources, achieving the best results with molasses.

Researchers such as Chaprão et al. (2015) [59], Almeida et al. (2017) [61], and Rane et al. (2017) [63] have utilized sugarcane molasses for biosurfactant production using Candida and Bacillus species. Their aim was to assess its potential for motor oil removal [63] and to optimize biosurfactant production through a response surface methodology and Plackett–Burman design. These approaches enhance process efficiency and lower costs by incorporating a low-cost carbon source [61,63].

Regarding PHB production, Dalsasso et al. (2019) [60] and Sen et al. (2018) [65] have proposed using Cupriavidus necator in SSF. One study evaluated the effect of combining molasses with stillage [60], while the other examined the impact of different molasses pretreatments on PHB production [65].

Machado et al. (2018) [55] explored molasses as an alternative carbon source for bacterial cellulose (BC) production using Komagataeibacter rhaeticus. They found that replacing conventional carbon sources with molasses-supplemented media maintained or even improved BC yield and mechanical properties, while reducing production costs by up to 20%.

In the field of biopolymer extraction, Tan et al. (2020) [64] demonstrated that sugarcane molasses could substitute glucose in a co-fermentation process to extract chitin from shrimp waste. The resulting chitin exhibited physicochemical properties comparable or superior to commercial standards, highlighting molasses’ potential in circular bioeconomy models.

Jones et al. (2019) [69] also confirmed the value of molasses as an effective medium for fungal growth, which could be harnessed for the production of chitinous nanomaterials. This highlights molasses as a key feedstock in sustainable material production.

The study by Gießelmann et al. (2019) [68] further exemplifies the versatility of molasses, demonstrating its use in the production of ectoine by Corynebacterium glutamicum. Through transcriptional balancing of the ectoine biosynthesis pathway, high titers were achieved under low-salt fermentation conditions, positioning molasses as a valuable substrate for industrial biotechnology.

For bioenergy purposes, De Vrieze et al. (2015) [66] emphasized that the biochemical methane potential (BMP) of molasses varies depending on the inoculum source, underlining the need for careful inoculum selection in anaerobic digestion systems to ensure optimal production. Arshad et al. (2017) [70] proposed a process to enhance ethanol production from molasses. Their approach involves using a very high gravity [VHG] system to lower ethanol production costs and reduce vinasse generation. VHG is a highly efficient fermentation technology at the industrial level, offering a higher ethanol yield (12–15%) compared to traditional fermentation (7–8%).

In summary, the studies reviewed highlight the significant intrinsic potential of molasses, which has led to numerous strategies for its valorization—either directly or through hydrolysis to increase its available monosaccharide content. Additionally, there are proposals aimed at optimizing existing processes that utilize molasses, such as ethanol, enzyme, or biopolymer production, as well as novel applications in bioenergy and environmental biotechnology.

4.2.2. Challenges in the Use of Sugarcane Molasses

Sugarcane molasses is a by-product rich in sugars (sucrose, glucose, and fructose) and other nutrients, making it a cost-effective option for fermentation processes in biorefineries, as seen in Brazil [58]. However, the simultaneous presence of these sugars presents a challenge, as they act as repressors that can inhibit cellulase production in conventional T. reesei strains. To efficiently utilize this resource, it is necessary to modify the producing strains [58].

Another major challenge is the need for pretreatment to optimize molasses for biotechnological processes. For instance, in the production of poly(3-hydroxybutyrate) (PHB) using C. necator DSM 545, molasses requires prior hydrolysis since this microorganism cannot directly assimilate sucrose [59]. Various methods, including chemical, enzymatic, and combined approaches, have been explored for sucrose hydrolysis. However, techniques such as hydrothermal treatment with sulfuric acid often result in low yields and the formation of inhibitor by-products like hydroxymethylfurfural (HMF), posing challenges for both efficiency and environmental sustainability [59,65].

Additionally, sugarcane molasses exhibits significant heterogeneity due to the presence of suspended particles and complex structures, which can negatively impact cell growth rates and fermentation efficiency. To address this, various pretreatment methods—such as activated carbon treatment—have been proposed to create a more homogeneous medium that enhances microbial production and optimizes substrate concentration for the synthesis of high-value molecules [51].

Moreover, ethanol production from molasses can generate large volumes of effluents with high biochemical and chemical oxygen demand (BOD and COD) levels. generating environmental challenges because inappropriate treatment of these effluents can lead to contamination. Therefore, optimizing and modernizing production processes is essential to achieving a sustainable ethanol production from molasses [70].

Managing the residues generated during molasses processing remains an unresolved challenge; for this reason, optimizing key parameters such as pH, organic acid composition, and the effective integration of pretreatment processes is crucial for enabling commercial scalability and reducing environmental impact [71]. Figure 2 provides a graphical summary of the potential products and challenges associated with the valorization of sugarcane molasses.

4.3. Sugarcane Vinasse

Sugarcane vinasse is a liquid by-product of ethanol production, generated from the fermentation of molasses or cane juice. It is obtained after ethanol distillation and is characterized by its high organic matter content, acidity (pH 3–5), and the presence of macro- and micronutrients such as potassium, calcium, magnesium, sulfates, and chlorides [72,73]. Its chemical composition consists of approximately 93–97% water and 3–7% solids, of which 75% is organic matter, including glycerol, lactic acid, ethanol, and acetic acid [72,74].

This by-product is produced in large volumes, with 8 to 18 L of vinasse generated per liter of ethanol produced [75]. In Brazil, for instance, the ethanol industry produced approximately 26 billion liters of ethanol during the 2012/2013 harvest season, resulting in around 312 billion liters of vinasse [76].

At the industrial level in Brazil, vinasse is primarily used for fertigation in sugarcane crops due to its nutrient content; however, excessive application can lead to soil (salinization, acidification, and eutrophication) and water contamination (toxic and cytotoxic effect on fauna), as well as greenhouse gas emissions [60,77]. Alternatively, vinasse has been explored as a substrate in biotechnological processes, including biogas production through anaerobic digestion, hydrogen generation, and fermentation for microbial biomass production using fungi and microalgae for industrial applications [60,73,78].

In this context, vinasse has been investigated as a substrate for methane, hydrogen, and organic acid production through various fermentation and co-digestion strategies. Methane generation, for instance, has been achieved through anaerobic co-digestion with glycerol, hemicellulose hydrolysate, yeast extract, and even fly ash from sugarcane bagasse combustion [79,80]. Regarding hydrogen, Dionizio et al. (2025) [81] reported that sugarcane vinasse supported fermentative H₂ production under both mesophilic and thermophilic conditions. Furthermore, Sánchez et al. (2020) [82] demonstrated the generation of isovaleric and caproic acids through co-fermentation of vinasse with cassava flour wastewater, contributing to the development of value-added carboxylates as part of a broader anaerobic biorefinery platform. Complementary studies have also highlighted vinasse’s potential in the production of short-chain fatty acids (SCFAs) and other bio-based chemicals via dark fermentation [83].

4.3.1. Biotechnological Approaches to Sugarcane Vinasse Utilization

The utilization of sugarcane vinasse has been approached from various perspectives in research studies over the last 10 years. This work compiles studies that use biotechnological tools for its valorization (

Table 3. Biotechnological strategies for the valorization of sugarcane molasses.

Ref.	Product	Application	Process
[60]	PHB	Plastic substitute	SmF
[76]	Biohydrogen	Biofuel	Anaerobic Digestion
[73]	Fungal biomass	Fish feed	SmF
[75]	Biomethane	Biofuel	Anaerobic Digestion
[72]	Bacterial cellulose	Biomedical	SmF
[78]	Methane	Biogas–Biofuel	Anaerobic Digestion
[84]	Bacterial cellulose	Textile industry, food processing, and pharmaceutical applications	SmF (Static)
[85]	Lacasse	Bioethanol, paper and cellulose, tissues, and animal feed	SmF
[86]	Biosurfactant and bacteriocin	Pharmaceutical/medicine, food, cosmetic, pesticide, oil, and biodegradation industries	SmF
[87]	Biomass	Bioremediation and biofuel	SmF
[88]	Hydrogen and methane	Biofuel	Anaerobic Digestion
[89]	Methane	Biofuel	Anaerobic Digestion
[90]	Biosurfactant (rhamnolipids)	Agriculture, cosmetics, pharmaceuticals, detergents, personal care products, food processing, textile manufacturing, laundry supplies, metal treatment and processing, pulp and paper processing, and paint industries	SmF
[91]	Chlorella vulgaris biomass	Value-added compounds for food, nutraceutical, cosmetic, and biofuel applications	Microalgae Cultivation (SmF)
[92]	Neochloris oleoabundans biomass	Biodiesel–Biofuel	Anaerobic Digestion

SmF: Submerged Fermentation.

). In this regard, the range of products that can be produced is extensive, with proposals including biofuels, microbial biomass, and biosurfactants, among others.

Similar to the case of molasses, there is a clear predominance of one biotechnological tool for the valorization of sugarcane vinasse, with anaerobic digestion being the most recurrent approach. It is important to recall that sugarcane vinasse is a residue characterized by its acidity, with a pH ranging from 3 to 5. This makes it logical to consider the production of biogas, such as hydrogen or methane, through anaerobic digestion. This process not only yields a valuable biofuel but also results in a digestate with reduced acidity, suitable for soil fertilization. This helps avoid the acidification that can arise from the excessive use of undigested vinasse [60].

In the case of vinasse, its utilization is clearly oriented toward the biofuels industry, followed by the pharmaceutical and food industries. Lastly, there are applications in other sectors such as medical, animal feed, and bioremediation [72,73,85,86]. Regarding the products that can be synthesized from vinasse, it is logical to observe a focus on biofuels like methane, biohydrogen, and biodiesel. However, other recurring products include bacterial cellulose, biosurfactants such as rhamnolipids, algal biomass, fungal biomass, and—in lesser proportion—enzymes like laccases, alongside other agents such as bacteriocins.

Recent studies also explore the potential of using vinasse as a culture medium for the production of chitinous materials derived from fungal mycelium. For example, Jones et al. (2019) [69] assessed the suitability of various agricultural by-products—including sugarcane residues—for fungal growth and the subsequent production of chitin nanofibers, which have applications in cosmetics, pharmaceuticals, composites, and water treatment.

Reviewing the advantages of anaerobic digestion, we note that using sugarcane vinasse not only enables methane production. Authors like De barros et al. (2016) [75] highlight that their strategy yielded a higher-quality effluent and stable sludge, allowing the recycling of nutrients from vinasse and the supplements obtained during treatment. The effluent can be reused for fertigation, while the sludge can be applied for plant fertilization. On the other hand, Júnior et al. (2015) [76] found in their study that biohydrogen production was short-lived and could not be sustained beyond 15 days in their system. However, despite the low hydrogen yields, sugarcane vinasse still holds potential for volatile fatty acid production.

Complementarily, Náthia-Nevesorcid et al. (2018) [88] demonstrated that the co-digestion of vinasse with food waste under mesophilic conditions not only enhanced the removal of total solids and volatile solids but also achieved high initial hydrogen concentrations (up to 76.5%) during the first days of fermentation. The biogas yield exceeded 300 mL/g of volatile solids, confirming the efficiency of such integrated systems.

However, not all strategies focus on biofuel production. For instance, Barshan et al. (2019) [72] concentrate on bacterial cellulose production, highlighting its wide range of applications, including wound healing, burn treatments, medical devices, tissue repair, paper manufacturing, and other applications. Due to its high purity, mechanical strength, crystallinity, biocompatibility, and biodegradability, bacterial cellulose has potential uses in various fields, particularly in the medical, electronics, and food packaging industries.

Authors such as Júnior et al. (2015) [76] and Quintero-Dallos et al. (2019) [91], on the other hand, focus on fungal and microalgal biomass production. Their research found that cultivating fungal biomass with vinasse (5%) yielded up to 118.5 g of dry matter per liter of culture medium, along with promising amino acid profiles suitable for use as fish feed. Meanwhile, Quintero-Dallos et al. (2019) [91] developed a method for producing Chlorella vulgaris biomass using vinasse as a culture medium, demonstrating that this by-product is a promising substrate for C. vulgaris production. Also, they characterized the maximum nutrient content of the biomass as 48.95% protein, 2.88% xylose, 7.82% glucose, 4.54% arabinose, 8.28% fructose, and 4.82% lipids.

Furthermore, ref. [92] used anaerobic effluents of vinasse for cultivating Neochloris oleoabundans, a biodiesel-producing microalga. Their results demonstrated increased cell density and lipid content when supplemented with bicarbonate, along with efficient nitrogen removal and flocculation, proving the viability of low-cost, dual-purpose production systems.

Sugarcane vinasse offers multiple biotechnological alternatives for the production of valuable metabolites. Its composition enables, for instance, biogas generation and the reuse of digestates as fertilizer. This approach not only minimizes the environmental impact of vinasse by utilizing its intrinsic components but also produces a by-product that can be reincorporated in processes such as fertigation or crop fertilization.

In addition to bioenergy and biomass production, vinasse and other sugarcane residues have been explored for the generation of high-value prebiotic compounds. Ávila et al. (2020) [93] enzymatically converted xylan from sugarcane straw into xylooligosaccharides (XOS) with proven antioxidant and probiotic-stimulating properties.

Similarly, Hernández-Pérez et al. (2016) [94] demonstrated xylitol production from sugarcane straw hydrolysates using Candida guilliermondii, reaching high yields through the optimization of oxygen availability and nutrient supplementation.

Also, Pratto et al. (2020) [95] successfully produced butanol via ABE fermentation from sugarcane straw pretreated with liquid hot water, showing promising yields without detoxification steps, thus confirming the potential of these residues in integrated biorefinery systems.

4.3.2. Challenges in the Use of Sugarcane Vinasse

The utilization of sugarcane vinasse presents significant challenges because of its biochemical composition and the biotechnological processes proposed for its treatment. For instance, the low carbon concentration in this by-product limits the production of biopolymers such as PHB, requiring its combination with carbon-rich substrates (e.g., sugarcane molasses) to enhance fermentative yields [60]. Likewise, the physicochemical properties of vinasse, particularly its acidity, reduce microbial activity, complicating its use in filamentous fungus cultures for biomass production intended as animal feed [73].

In the field of energy generation, using vinasse in anaerobic processes also faces major challenges. Anaerobic digestion for biogas production must overcome issues related to high organic loads and the presence of toxic compounds in vinasse, which hinder both reactor start-up and operational stability [75,78,88,89]. Additionally, refractory and inhibitory compounds, such as phenols, melanoidins, and other fermentation by-products, limit its potential in enzyme and biomolecule production, affecting processes like laccase and biosurfactant synthesis [85,86,87].

Finally, other alternatives have been explored to convert vinasse into a high-value resource, such as the production of cellulose-producing bacteria and the cultivation of microalgae. These strategies offer the potential to transform a potentially polluting waste into a valuable industrial input, although their implementation requires overcoming challenges related to the variability in chemical composition and the adverse conditions inherent to vinasse [84,91]. Figure 3 provides a graphical summary of the potential products and challenges associated with sugarcane vinasse valorization.

4.4. Sugarcane Straw

Sugarcane straw is a lignocellulosic residue composed primarily of dry leaves and green tops that remain after harvesting sugarcane. Its chemical makeup is rich in cellulose (ranging from 34.2% to 50%), hemicellulose (23.2–29%), and lignin (approximately 19–25%), with smaller amounts of ash and protein [93,95].

This by-product is generated during the harvesting stage of sugarcane industrialization. With the shift from traditional burning practices to mechanized, non-burning harvesting systems, more straw is left in the field rather than being incinerated. In fact, mechanization and green management techniques have significantly increased the availability of sugarcane straw, as these practices allow for its recovery and potential use in various industrial applications [94,96].

In terms of production volumes, Brazil—the world’s largest sugarcane producer—generates approximately 92 million tons of sugarcane straw annually [97]. Moreover, for each ton of harvested sugarcane, around 140 kg of straw is produced, leading to an estimated production of about 106.2 million tons of straw in a typical harvest season [98].

The potential uses for sugarcane straw are diverse. Traditionally, it has been returned to the soil as a mulch to enhance soil fertility and organic matter dynamics. However, due to its significant lignocellulosic content, it is also being explored as a feedstock for bioethanol production and as a raw material for generating energy and valuable co-products such as fermentable sugars and xylanolytic enzymes [97,99].

4.4.1. Biotechnological Approaches for the Utilization of Sugarcane Straw

The use of sugarcane straw remains limited; however, there is growing interest in exploiting this residue for the production of high-value products through biotechnological approaches (

Table 4. Biotechnological processes for the valorization of sugarcane straw.

Ref.	Product	Application	Process
[97]	Bioethanol	Biofuel	Biocatalysis and SSF
[95]	Biobutanol	Biofuel	Biocatalysis and SSF
[93]	XOS	Food industries (sweeteners, stabilizers, emulsificants, prebiotics)
[94]	Xylitol	Food, odontological, and pharmaceutical industries	SmF
[100]	Oyster mushroom	Food	SSF
[101]	n-butanol	Biofuel	SmF
[102]	Cellooligosaccharides	Biofuel, food, and feed	Biocatalysis
[96]	Xylanases	Paper industry (biobleaching)	SmF
[103]	Enzymatic cocktails	Food, paper-pulp, animal feed, laundry detergents, and second-generation bioethanol production	SmF
[104]	Cellulases	Lignocellulose saccharification	SmF
[99]	Enzymes and XOS	Functional foods (prebiotics)	SmF and Biocatalysis
[105]	Xylooligosaccharide microparticles	Functional foods (prebiotics)	Biocatalysis
[98]	Butyric acid	Chemical, pharmaceutical, food, and feed industries	Biocatalysis and SmF
[106]	Cellooligosaccharides	Food, chemical, and pharmaceutical industries	Biocatalysis
[107]	Enzymatic cocktail	Biofuel	SmF

SmF: Submerged Fermentation; SSF: Solid-State Fermentation.

). Over the past decade, several notable studies have explored sugarcane straw as a primary or supporting component in the synthesis of value-added products.

Regarding the biotechnological strategies employed, SmF is the most used, followed by biocatalysis. However, some studies integrate multiple biotechnological approaches. When analyzing the cases where biocatalysis and SmF are used, either individually or in combination, a balanced distribution of biotechnological tools in studies is observed.

The analyzed studies highlight the versatility of sugarcane straw in biotechnological and industrial applications, revealing similarities in objectives and methodologies. For instance, several studies focus on converting this residue into biofuels, optimizing pretreatment and fermentation processes to produce ethanol or butanol, as demonstrated in studies by Da Silva et al. (2019) [107], Pratto et al. (2020) [95], and Fonseca et al. (2020) [98]. These studies assess the impact of pretreatment conditions, such as alkaline loading or acid concentration, to enhance sugar release and subsequent fermentation.

Similarly, some studies focus on the production of high-value metabolites, such as oligosaccharides with prebiotic and functional properties. Research works like Ávila et al. (2020) [93], Barbosa et al. (2020) [102], Martins et al. (2020) [99], Martins et al. (2020) [105], and Ávila et al. (2023) [106] propose enzymatic methodologies for synthesizing xylo- and cello-oligosaccharides, optimizing enzyme activity and exploring their applications in the food and pharmaceutical industries as sweeteners, stabilizers, emulsificants, and prebiotics.

There is also significant interest in obtaining and enhancing lignocellulolytic enzymes from straw-based cultures, which facilitate biomass saccharification and the conversion of its components, as demonstrated in studies by Piccinni et al. (2018) [103], Viera et al. (2020) [104], and Da Silva et al. (2019) [107]. These studies focus both on optimizing production conditions and exploring the potential of novel microbial and fungal isolates to obtain enzymes with greater activity and specificity.

Finally, the range of approaches extends from valorizing sugarcane straw for the production of sweetening compounds such as xylitol [94] to improving substrates for the cultivation of edible fungi [100]. Collectively, these studies share the goal of maximizing the use of sugarcane straw by optimizing processes and implementing novel methodologies that enhance biofuel production, as well as the extraction of bioactive compounds and enzymes.

4.4.2. Challenges in the Use of Sugarcane Straw

The use of sugarcane straw has several challenges that must be addressed to develop competitive and efficient biotechnological processes.

One of the primary challenges is pretreatment. These processes, which are essential for enhancing cellulose accessibility, often generate various undesired by-products, such as phenolic compounds, organic acids, and furan derivatives, which act as inhibitors during fermentation [95,97,101] The formation of these compounds not only reduces biomass conversion efficiency but also necessitates additional detoxification steps, increasing the overall cost of the process.

Another critical challenge is the high cost and limited efficiency of enzymatic hydrolysis. This step, which accounts for 20–30% of the total cost in bioethanol and metabolite production, is hindered by residual lignin and by-products such as cellobiose, which can inhibit enzyme activity [97,102,106,107]. The non-productive interaction of enzymes with lignin and the accumulation of hydrolysis products highlight the need for more specific enzyme cocktails and stepwise hydrolysis strategies to minimize inhibition and improve yields.

Moreover, differences in optimal operating conditions between enzymatic hydrolysis and fermentation (e.g., temperature) introduce additional constraints. Process configurations that integrate presaccharification and simultaneous saccharification and fermentation stages have shown potential in mitigating these issues, but they also require greater control and operational complexity [95,97].

On the other hand, variability in the composition of sugarcane straw—strongly influenced by variety and yield—introduces an additional layer of uncertainty to the process. This heterogeneity impacts both pretreatment efficiency and enzyme production, requiring adjustments to operating parameters for each batch of biomass [96].

Figure 4 provides a graphical summary of the potential products and challenges associated with the valorization of sugarcane straw.

5. Strategic Approaches to Overcoming Biotechnological Challenges and Transitioning to Sustainable Alternatives

Despite the growing adoption of waste valorization technologies in countries like Brazil and China, significant disparities persist in their implementation across regions, particularly in low-resource settings [10]. For instance, while Brazil has successfully commercialized sugarcane bagasse for energy recovery, India still disposes of much of its bagasse ash in landfills, highlighting gaps in technology transfer and infrastructure. Key barriers include high capital costs, technical inefficiencies (e.g., in emerging processes like biohydrogen production), and insufficient logistical frameworks for feedstock supply [10,108]. In developing economies, these challenges are exacerbated by limited energy infrastructure, fragmented policy support, and socioeconomic constraint factors that hinder the scalability of advanced bioprocesses such as solid-state fermentation (SSF). Fit et al. (2025) [108] further emphasize that region-specific conditions, including feedstock availability, transportation costs, and societal acceptance, critically influence the viability of biorefineries. To bridge these gaps, tailored strategies—such as decentralized energy-efficient systems, co-product diversification, and policy incentives—are essential to align technological solutions with local capacities and circular economy goals.

5.1. Mitigation of Inhibitory Compounds During Biotechnological Processing

One of the main bottlenecks in the biotechnological valorization of sugarcane industry by-products is the presence of inhibitory compounds generated during the pretreatment or hydrolysis of lignocellulosic biomass. These include furfural, hydroxymethylfurfural (HMF), phenolic compounds, organic acids, and melanoidins, which can significantly affect microbial metabolism, enzyme activity, and overall fermentation performance.

Various strategies have been explored to reduce or eliminate these inhibitory compounds, either by optimizing pretreatment conditions or applying post-treatment detoxification steps. For instance, liquid hot water (LHW) pretreatment has been reported to generate lower levels of inhibitors compared to acid hydrolysis or steam explosion [95]. Similarly, microwave-assisted pretreatment can reduce HMF formation by accelerating reaction kinetics and reducing activation energy [65].

In terms of detoxification, the use of activated charcoal has proven highly effective across multiple studies. Fonseca et al. (2020) [98] and Bonturi et al. (2017) [47] reported significant reductions in furfural, HMF, acetic acid, and phenolic compounds with activated carbon treatments ranging from 2 to 10% (w/v). Moreover, overliming with Ca(OH)₂ has been shown to reduce furfural, HMF, and phenolics, while also neutralizing residual acid post-hydrolysis [49].

Additional chemical approaches include pH neutralization with CaO and H₃PO₄, ion exchange resins for acetic acid and calcium removal, and steam stripping under reduced pressure to eliminate volatile inhibitors such as furfural [49]. Other biological alternatives, such as the adaptive evolution of yeast strains, have been proposed to increase microbial tolerance without the need for detoxification, thereby reducing process costs [47].

Finally, indirect strategies such as hydrolysate concentrations to optimize the C/N ratio [47] or the enzymatic degradation of complex inhibitors (e.g., melanoidins and polyphenols by fungi; Chuppa-Tostain [87]) have also contributed to improved fermentation outcomes. These approaches, though diverse, highlight the importance of tailoring mitigation strategies to the specific feedstock, microbial system, and biotechnological platform employed.

5.2. Traditional Products vs. Bio-Based Products

Environmental impact is a critical dimension when evaluating the sustainability of bioproducts derived from sugarcane industry by-products. Life-cycle assessment (LCA) data support the environmental advantages of replacing fossil-based products with biobased alternatives such as PHAs, PLA, bioethanol, and biogas. For instance, the LCA conducted by NatureWorks LLC (Minnetonka, MN, USA) on polylactic acid (PLA) showed that switching to renewable energy sources in production processes reduced carbon emissions by up to 90%, positioning PLA as a lower-impact alternative to PET and aluminum packaging [109]. Similarly, PHAs offer strong advantages due to their complete biodegradability under both aerobic and anaerobic conditions, without releasing toxic intermediates—an important distinction from conventional plastics.

In the case of bioethanol, molasses-based production results in significantly lower greenhouse gas emissions compared to gasoline. According to Farahani and Asoodar (2017) [110], the use of 1000 L of molasses-derived bioethanol instead of its fossil fuel equivalent results in net avoided emissions of over 500 kg CO₂-eq. Furthermore, its global warming potential, acidification, and eutrophication impacts are notably reduced, especially when energy efficiency improvements—such as using bagasse as fuel or replacing synthetic fertilizers—are implemented.

Biogas production from sugarcane vinasse also demonstrates meaningful environmental benefits. As reported by Parsaee et al. (2019) [111], methane emissions can be reduced by 78%, and nitrous oxide by 100%, compared to traditional vinasse disposal on fields. Controlled anaerobic digestion not only reduces pollutant emissions and odor generation but also contributes to renewable energy production and decreases reliance on diesel for agricultural operations. Additionally, the digestion process lowers the chemical and biological oxygen demand of vinasse, reducing its environmental impact if discharged.

Together, these findings confirm that biotechnological valorization strategies not only recover value from agroindustrial waste but also offer clear environmental benefits when compared through life-cycle indicators to conventional processes. Including such metrics in future research will be essential for validating the full sustainability potential of sugarcane-derived bioproducts.

Figure 5 illustrates an integrated scheme for the biotechnological valorization of sugarcane by-products. The workflow highlights the importance of pretreatment for enhancing substrate accessibility, followed by detoxification steps to reduce inhibitory compounds such as furfural and HMF. It then shows the use of biotechnological tools that enable the production of value-added bioproducts like bioethanol, bioplastics, and biosurfactants. This visual synthesis supports the strategies discussed in this section and underscores the role of integrated systems in overcoming biochemical and operational limitations.

6. Future Perspectives

In many countries, the sugarcane industry is a massive sector that generates tons of by-products each year, many of which have significant potential for reutilization. However, in many regions, their utilization remains suboptimal or even non-existent. Interest in these by-products remains, and for years, efforts have been directed toward developing biotechnological processes to obtain high-value products from agroindustrial residues; these strategies could also be applied in the future to sugarcane industry by-products.

The production of animal feed and the enhancement of the nutritional value of agroindustrial residues remain active areas of study. For example, Hong et al. (2025) [112] proposed the use of a microbial consortium consisting of Bacillus subtilis, Lactobacillus plantarum, Erwinia tasmaniensis, and Enterococcus gallinarum to improve the nutritional value of rapeseed meal. Their study demonstrated improvements in crude protein content, amino acid profile, flavor, and digestibility, along with a reduction in anti-nutritional compounds such as glucosinolates (86.08%), phytic acid (59.41%), and tannins (72.88%).

Another approach involves the isolation of fungal strains for the production of hydrolytic enzymes, as explored in the study by Wagner et al. (2025) [113]. They investigated the valorization of brewers’ spent grains to produce lignocellulolytic enzymes and fermentable monosaccharides, finding that the Filobasidium 4796 strain has significant potential for enzyme production and the bioconversion of lignocellulosic residues.

However, to enhance the production of hydrolytic enzymes for lignocellulosic biomass utilization, modern gene-editing tools have also been employed. For instance, Liu et al. (2025) [114] used CRISPR/Cas9-mediated gene editing on a Bacillus subtilis strain, successfully increasing the production of endoglucanases by 3.1-fold, exoglucanases by 6.6-fold, β-glucosidases by 3-fold, xylanases by 1.2-fold, and total cellulases by 1.8-fold.

Another strategy adopted by researchers is the in situ production of enzyme cocktails, as demonstrated in the study by Pan et al. (2025) [115]. They highlight that in situ production is considered a viable alternative to enhance the profitability of biorefineries. In their study, they used Chaetomium globosum in an SSF system to produce an enzyme cocktail, which was then applied to various lignocellulosic biomasses for hydrolysis, yielding better results compared to commercial enzyme cocktails such as Cellic CTec 2.

Another interesting product that can be derived from sugarcane industry by-products is polyhydroxyalkanoates (PHAs). In this regard, Castilla-Marroquín et al. (2025) [116] propose an approach focused on exploring the potential of bacterial isolates from the sugar industry and optimizing conditions such as temperature, initial pH, and incubation time to enhance PHA production in an SmF system.

For the utilization of sugarcane molasses, the study by De Carvalho et al. (2024) [117] proposes the production of bacterial cellulose in a static fermentation system using Gluconacetobacter hansenii, with sugarcane molasses as the primary carbon source. Additionally, the authors analyzed the characteristics of the resulting cellulose, highlighting its nanoscale fiber size, transparency, porosity, tensile strength, water activity, and swelling rate. These properties confirm that bacterial cellulose particles are promising candidates for medical applications, such as wound dressings after surgery.

Similarly, Lin et al. (2024) [118] propose the use of a genetically modified strain of Cupriavidus necator (Lgg-H16) for the production of polyhydroxybutyrate (PHB) in a fed-batch fermentation system, incorporating sugarcane molasses as a low-cost carbon source. In the same sense, the use of SSF has been explored by León et al. (2025) [119]. In this study, the proposed approach involves using a mixture of carbon sources (sorghum green malt and molasses) with Saccharomyces bayanus as the fermentative organism. Additionally, a Taguchi L9 (34) experimental design was employed to evaluate the effects of molasses concentration, urea, and CaCO₃, as well as initial pH, on bioethanol yield.

Regarding strategies such as anaerobic digestion, recent studies like that of Borges et al. (2024) [120] have explored two-phase anaerobic digestion systems, where an initial sulfidogenesis stage improved process efficiency compared to single-phase systems. This approach addresses the challenges posed by the high sulfate concentrations (>2 g/L) in vinasse, which can be toxic to microorganisms and disrupt process stability. Implementing two-phase anaerobic digestion systems could be a promising solution for optimizing biogas production and sulfate removal in the sugar industry.

Meanwhile, Ribeiro et al. (2024) [121] propose an anaerobic co-digestion system using vinasse and sugarcane molasses (1:1) in a thermophilic fluidized-bed reactor. Their findings indicate that the organic loading rate significantly influences methane production and microbial consortium stability during anaerobic co-digestion. This suggests that optimizing process conditions could maximize energy yields while maintaining methanogenic balance.

In addition to these strategies, recent advancements in biotechnological tools offer further opportunities to improve the efficiency, environmental performance, and practical scalability of sugarcane by-product valorization processes. Novel approaches such as genome editing, enzyme immobilization, and ionic liquid (IL)-based pretreatments are increasingly being explored in the context of lignocellulosic biomass conversion. One promising development is the application of CRISPR/Cas9 gene editing to engineer microbial strains with enhanced degradative capacity. For example, Liu et al. (2025) [114] developed a strain of Bacillus subtilis (AEA3) with chromosomally integrated cellulase genes, which improved lignocellulose breakdown efficiency while avoiding the use of antibiotic resistance markers.

Enzyme immobilization systems—such as cross-linked enzyme aggregates (CLEAs) and advanced polymeric carriers—have also gained traction as platforms to improve enzyme resilience and operational consistency. These systems allow enzymes to be reused over multiple cycles and remain stable under industrially relevant conditions, making them particularly suitable for high-throughput and resource-conscious applications.

Additionally, IL-based pretreatments have shown great potential to reduce cellulose crystallinity and increase enzymatic accessibility by disrupting lignocellulosic structures. Studies by Hou et al. (2017) [122] and Zhang et al. (2021) [123] have demonstrated the use of ILs to facilitate sugar recovery and enable integrated “one-pot” processes that streamline pretreatment, hydrolysis, and fermentation. Their recyclability and low environmental impact further support their suitability in modern biorefinery frameworks.

Collectively, these innovations represent a shift toward more refined and sustainable process designs that align with industrial needs and environmental stewardship. Their integration into future sugarcane by-product valorization schemes will likely play an important role in advancing the sector toward greater technological maturity and financial sustainability.

The interest in valorizing agroindustrial waste continues to evolve with constant improvements and innovations. Approaches such as the isolation of novel microbial strains, the design of microbial consortia, the use of multiphase anaerobic digestion, and the combination of by-products such as vinasse, molasses, and bagasse are increasingly being explored to optimize microbial growth conditions and improve the overall productivity of biotechnological processes. These strategies aim to improve nutrient balance and reduce operational costs through synergistic substrate use. However, integrating such approaches has some challenges. One of the major barriers is the compositional variability of mixed substrates, which can differ significantly depending on geographic origin, crop variety, harvest season, and pretreatment methods. This variability affects the consistency of fermentation processes and the efficiency of downstream applications (Rocha et al. (2024) [31], Dalsasso et al. (2019) [60]).

Meanwhile, to overcome limitations in the use of lignocellulose by-products and hydrolysates (like sugarcane ones), recent studies highlight the importance of targeted strain engineering. For instance, stress-resilient microbial strains have been developed through adaptive laboratory evolution, membrane engineering, and the overexpression of detoxification genes to tolerate inhibitors such as furfural, HMF, acetic acid, and phenolic compounds—common by-products in lignocellulosic hydrolysates (Wang et al. (2018) [124], Yang et al. (2018) [125]). In particular, efflux pump engineering and the use of NADH-dependent oxidoreductases (e.g., FucO) have improved microbial tolerance and fermentation performance (Shan et al. (2023) [126]). Moreover, omics-based approaches have allowed the identification of key regulatory genes and pathways involved in inhibitor resistance, enabling more precise metabolic engineering strategies.

Altogether, while the potential of using mixed agroindustrial by-products and advanced microbial systems is promising, future efforts must address the integration challenges associated with feedstock variability and strain robustness. Tailoring microbial traits to specific substrate profiles and process conditions will be critical to ensure the stable and scalable bioconversion of sugarcane residues into high-value products.

7. Conclusions

The sugarcane industry generates significant quantities of by-products, such as bagasse, molasses, vinasse, and straw, which hold immense potential for valorization through biotechnological approaches. These residues can be transformed into high-value products, including biofuels, biosurfactants, hydrolytic enzymes, cellulose nanofibers, sugars, organic acids, microbial biomass, and more. Biotechnology plays a pivotal role in this transformation, utilizing tools like submerged fermentation, solid-state fermentation, biocatalysis, and anaerobic digestion. However, challenges such as the heterogeneous nature of these by-products, the presence of inhibitors (e.g., furfural and hydroxymethylfurfural), high enzyme costs, and technical limitations in solid-state fermentation and biodigestion hinder their large-scale application.

To address these challenges and enable circular economy transitions, future research should prioritize strategies for lignin valorization, as this component remains underutilized despite its potential for producing sustainable chemicals and materials. Additionally, policy recommendations are needed to incentivize the adoption of integrated biorefinery models, which maximize resource efficiency and minimize waste. Governments and industries should collaborate to establish frameworks that support the development of cost-effective pretreatment methods, promote microbial strain optimization, and encourage the use of renewable energy in bioprocessing systems.

Emerging trends, such as the use of microbial consortia, gene-editing tools like CRISPR/Cas9, enzyme immobilization, and ionic liquid-based pretreatments, offer promising avenues for improving process efficiency and scalability. Furthermore, integrating multiphase anaerobic digestion systems and co-digestion strategies (e.g., combining vinasse and molasses) can enhance energy yields and reduce environmental impacts. By leveraging these innovations and aligning them with policy initiatives, the sugarcane industry can transition toward more sustainable production systems, contributing to global efforts in reducing carbon footprints and fostering a circular bioeconomy.