Upcycling Wine Industry Waste: Dealcoholized Grape Pomace as a Platform for Bio-Based Material Innovation

Abstract

The wine industry produces substantial amounts of organic waste, particularly in the form of dealcoholized grape pomace—the primary residual biomass that remains after the fermentation process and the extraction of alcohol from winery by-products. This study explores the potential of upcycling dealcoholized pomace, an often-overlooked by-product, into a sustainable platform for innovative bio-based materials. Using a multidisciplinary approach that combines materials science, biotechnology, and principles of the circular economy, we carefully examine the physical, chemical, and mechanical properties of dealcoholized pomace. Our research includes comprehensive analyses of its structural integrity, biodegradability, and potential applications, including biocomposites, eco-friendly packaging solutions, and other sustainable materials. The results of our study highlight not only the promising performance characteristics of dealcoholized pomace, such as its strength-to-weight ratio and biocompatibility, but also underscore its significant role in advancing waste valorization strategies. By effectively transforming waste into valuable resources, we contribute to the development of sustainable materials, thereby supporting a more circular economy within the wine industry and beyond.

1. Overview of Wine Production

Although global wine production and consumption show a declining trend, 237.3 million hectoliters were produced in 2023, with 144.5 million hectoliters originating from the European Union alone [1]. Annual wine industry operations consequently involve not only harvesting, transporting, and processing millions of tonnes of grapes but also managing large amounts of liquid effluents and biowastes, including grape stalks, grape marc (pomace), wine lees, and winery waste-activated sludge. The proper disposal of these by-products represents a technical challenge and a significant financial investment. However, if untreated, these residues pose a serious environmental risk [2].

In the European Union, which for decades has included five of the world’s top ten wine-producing countries, regulatory measures promote the valorization of grape pomace (GP) and wine lees [3,4,5]. These policies offer financial incentives for wineries to deliver such by-products to authorized distilleries, where valuable compounds, such as grape pigments for the food industry, ethanol used as bioethanol or a raw material in fortified wines and spirits, and calcium tartrate for tartaric acid production, can be recovered [6].

Although estimates of the volume of GP generated as a by-product of winemaking vary depending on grape variety, vineyard practices, and processing techniques [7], there is general agreement that it accounts for 15 to 25% of the total processed grape weight [8,9], corresponding to approximately 4.7 to 7.9 million tonnes worldwide in 2023.

1.1. Definition and Composition of GP

Fresh grape pomace (GP) can be broadly defined as the solid residue composed of skins, seeds, and occasionally stems, resulting from grape pressing, which may or may not contain unfermented sugars [7].

This complex and heterogeneous bio-waste consists of approximately 425 kg of grape skins, 225 kg of grape seeds, and 249 kg of grape stalks (GS) per tonne, with a high and variable moisture content ranging from 50% to 72% [7]. Among the structural and bioactive compounds present, lignin, pectic substances, sugars, proteins, minerals, and phenolic compounds were quantified [8,10,11,12,13,14] (

Table 1. Representative composition of GP (g/100 g, fresh weight basis).

Component	Amount	References
Moisture content	50–72	[7]
Lignin	16.8–24.2	[10]
Pectic substances	~20	[8]
Soluble sugars	1.5–6.2	[10,11]
Proteins	2.7–3.8	[10,14]
Phenolic compounds	5–10	[12,13]
Minerals	1.8–4.6	[10,11]

).

Traditionally, GP undergoes two distinct unit operations for recovering valuable substances. The choice of extraction process hinges on the unfermented sugar content and the levels of tartrate and grape pigments.

Fermented pomace from red wine production, which has low residual sugar, can be directly subjected to steam stripping distillation if ethanol recovery is the only desired outcome. The resulting product is a hydroalcoholic solution containing between 20 and 35% alcohol by volume (v/v), along with small amounts of ethyl acetate, methanol, and acetic acid. This solution is subsequently redistilled in appropriate columns to yield an alcohol with a concentration of 52–80% (v/v). This process is known in the wine industry as pomace “dealcoholization” (Figure 1).

Conversely, pomace from white or fortified wine production, still rich in unfermented sugars, is subjected to a countercurrent leaching process. This yields a dilute hydroalcoholic solution (approximately 3% (v/v) alcohol and 30–50 g/L sugars), which is then fermented to increase its alcohol content before distillation. Similarly, if red pomace contains sufficient grape pigments or tartrates to warrant extraction, the same leaching process is applied, followed by concentration of the heat-sensitive dilute pigment solution at low temperatures using a multiple-effect evaporator (Figure 2).

In the case of dealcoholized grape pomace (DGP), large-scale industrial applications typically involve partial dehydration by pressing, followed by drying in rotary furnaces to a final moisture content of approximately 5%. This process stabilizes the material microbiologically, enabling sieving to separate grape skins from seeds. Industrially, the recovered seeds can be used for grape seed oil extraction, as a component in animal feed, or as an efficient solid biomass fuel [15].

If no viable market exists for the seeds, or if the distillery lacks steam generators powered by solid fuels, the DGP may be used as soil mulch, as an organic amendment, or be composted—often in combination with other bio-wastes that offer a complementary C/N ratio [16,17].

While the recovery of specific bioactive compounds is affected by the dealcoholization processes mentioned earlier [18], structural compounds are largely unaffected by the conditions used due to their high thermal stability and low water solubility [19].

1.2. Rationale for Upcycling in the Context of the Circular Economy and Bioeconomy

As a result of seed separation after drying dealcoholized grape pomace, a new lignocellulosic material composed mainly of grape skins is now produced. This material is sometimes known as spent seedless grape pomace (SSGP).

In recent years, beyond its traditional uses, there has been growing interest in applying circular economy principles to enhance the value of SSGP [20]. Initial research has identified several valuable classes of compounds present in SSGP [21,22], including dietary fibers [23] and bioactive compounds with antioxidant, anticancer, cardioprotective, and anti-inflammatory activities [24,25,26].

Additionally, SSGP contains components with functional properties such as food colorants, texturizing agents, and natural antioxidants [27].

More recent studies have shifted focus toward developing sustainable extraction methods and optimizing conditions to maximize the recovery of these compounds [28,29]. Researchers have also begun exploring the use of SSGP as a second-generation feedstock for synthesizing polymer building blocks or as a reinforcing filler in composite materials [30].

Within the framework of the circular economy, the upcycling of SSGP contributes directly to reducing biomass waste and greenhouse gas emissions, extending material life cycles, and improving resource efficiency across the agri-food sector. Although dealcoholization may slightly reduce the levels of specific bioactive compounds, SSGP still retains a significant portion of its original composition, making it a versatile input for the development of secondary products. This makes it a valuable and versatile input for the development of secondary products. Its composition supports a wide range of applications, including food ingredients, dietary supplements, cosmetics, and biodegradable materials, which reduce our reliance on synthetic additives and non-renewable resources [31]. Furthermore, the removal of alcohol enhances the safety and regulatory compliance of these applications, particularly in food and nutraceutical products, by lowering ethanol content to acceptable or negligible levels [32].

From a bioeconomy perspective, valorizing SSGP supports a regenerative model in which biomass is repurposed efficiently and repeatedly across different sectors. This approach aligns with EU and global bioeconomy strategies by fostering local value chains and promoting rural development, especially in wine-producing regions where large volumes of pomace are generated annually [33,34]. When combined with green extraction technologies, such as supercritical CO₂ or subcritical water extraction, or when integrated into biopolymer systems based on polylactic acid (PLA), poly(butylene succinate), or starch derived from agri-food by-products, SSGP enables the sustainable recovery of high-value compounds. These innovations offer a low environmental impact and reinforce the role of bio-based solutions in accelerating the transition to a more sustainable industry [35].

2. Physicochemical Properties of SSGP

As mentioned earlier, because DGP is inherently prone to microbial instability, whether produced by steam distillation or countercurrent leaching, drying is always required if it is not intended for composting [36,37,38]. For this reason, the final physicochemical characteristics of SSGP are only marginally influenced by grape variety and winemaking method and are primarily determined by thermal and oxidative effects (

Table 2. Representative composition of SSGP (g/100 g, as-is basis).

Component	Amount	References
Moisture content	3–7	[36,37]
Lignin	27–56	[26,37,39]
Proteins	2.8–3.0	[36]
Phenolic compounds	0.5–0.6	[38]
Minerals	1.5–10	[36,37]

).

A comparison of GP (Table 1) and SSGP (Table 2) reveals significant physicochemical transformations resulting from processing. Most notably, SSGP exhibits a drastically lower moisture content (3–7%) compared to the high moisture levels of fresh GP (50–72%), indicating extensive drying. This drying and leaching process also leads to the complete removal of soluble sugars from SSGP, which are present at 1.5–6.2% in fresh GP. Phenolic compounds are substantially reduced, decreasing from 5–10% in GP to just 0.5–0.6% in SSGP. Conversely, the removal of moisture and soluble components results in a relative concentration of other constituents: lignin content increases from 16.8–24.2% in GP to a much higher 27–56% in SSGP. Protein levels remain relatively consistent (2.7–3.8% in GP vs. 2.8–3.0% in SSGP), while mineral content in SSGP (1.5–10%) exhibits a broader range and a potentially higher upper limit than in GP (1.8–4.6%). Pectic substances, prominent in GP (~20%), are not reported for SSGP, suggesting their removal or significant alteration.

3. Pretreatment and Processing Technologies

Efficient processing and extraction of DGP and SSGP necessitate appropriate pretreatment methods to disrupt the complex plant cell wall matrix and enhance the accessibility and recovery of target molecules such as bioactive polyphenols and dietary fibers. These pretreatments can be broadly categorized into mechanical, chemical, and enzymatic approaches, often used in combination to maximize yields and product quality.

Mechanical pretreatments are fundamental first steps, primarily involving drying, milling, and size reduction. Drying is crucial for reducing moisture content, preventing microbial spoilage, concentrating compounds, and preparing the material for subsequent processing. Methods such as convective air drying, freeze-drying, and microwave-assisted drying are employed, with the choice influencing energy consumption and the preservation of thermolabile compounds, including certain polyphenols [40]. Following drying, milling or grinding reduces particle size, significantly increasing the surface area available for solvent penetration and interaction. This enhanced surface area is directly correlated with improved extraction efficiency of both polyphenols and the subsequent accessibility of dietary fiber components [41].

Chemical pretreatments predominantly involve the use of solvents for extraction, but they can also include treatments to modify fiber structure. For the extraction of phenolic compounds, solvents such as water, ethanol, methanol, acetone, and their aqueous mixtures have been investigated. Ethanol–water mixtures are particularly favored due to their Generally Recognized as Safe (GRAS) status and their ability to efficiently extract a broad range of substances. The choice of solvent, temperature, and extraction time is a critical parameter influencing yield and selectivity [42]. Emerging green solvents, such as deep eutectic solvents (DES), are also gaining attention for their efficacy and environmental benefits. For dietary fiber modification or isolation, mild acid or alkaline treatments can be used to hydrolyze hemicellulose or delignify the material, making cellulose more accessible. However, this process must be carefully controlled to preserve other valuable components.

Enzymatic pretreatments provide a more targeted and gentle approach to deconstructing the plant cell wall, thereby releasing entrapped bioactive compounds and modifying the characteristics of dietary fiber. Enzymes such as cellulases, hemicellulases, pectinases, and tannases can be used individually or in combinations. These enzymes catalyze the hydrolysis of specific polysaccharides, including cellulose, hemicellulose, and pectin, which form the structural backbone of the cell wall. This process improves the release of polyphenols and increases the soluble dietary fiber fraction. Enzyme-assisted extraction (EAE) often yields higher polyphenol concentrations under gentler conditions, such as lower temperatures and less organic solvent, compared to conventional methods, thereby preserving their bioactivity [43]. Furthermore, enzymatic treatment can enhance the functional properties of dietary fibers, such as their water-holding capacity and fermentability.

4. Dealcoholized Grape Pomace Applications in Bio-Based Materials

4.1. Bio-Based Materials Used in Our Daily Life

Bio-based materials are increasingly used in daily life as sustainable alternatives to petroleum-based products. These materials are derived from renewable biological resources and are found in a wide range of everyday applications, helping to reduce our environmental impact and support a circular economy.

Made from natural resources such as corn starch, cellulose, sugarcane, and agri-food by-products, bioplastics are used in packaging, cutlery, bowls, straws, and other applications. They are biodegradable or partially biodegradable, making them less harmful to the environment compared to conventional plastics [44,45,46,47,48], as shown in

Table 3. Summary of some bio-based materials used in our daily life, including their source and composition.

Bio-Based Material	Daily Life Application(s)	Source/Composition	Reference(s)
Fungal-based biomaterials	Packaging, textiles, leather alternatives, automotive, insulation, fire protection	Fungal mycelium, lignin/cellulose waste	[49]
Bio-polyethylene (Bio-PE), Bio-polypropylene (Bio-PP), Bio-PET	Packaging, durable goods, and electronics	Biomass-derived monomers	[44]
Biofibers, biopolymers, biocomposites	Construction, engineering, biomedical, and commercial products	Cellulose, starch, chitosan, natural fibers	[50,51]
Bioplastics from fruit waste	Packaging, cutlery, bowls, straws	Orange peel (cellulose), corn starch, sugarcane bagasse	[45]
Polylactic acid (PLA), Polyhydroxyalkanoate (PHA), cellulose, starch, proteins, lipids, waxes	Packaging, textiles	Plant-based polymers, natural resources	[46]
Biodegradable nanofiber materials	Energy, environmental, and biomedical applications	Starch, cellulose, chitosan, PLA, PCL	[51]

.

Materials such as cellulose, starch, and chitosan are processed into fibers, films, and composites for use in construction, textiles, and engineering, offering renewable and sustainable alternatives to synthetic materials [50,51]. Fungal mycelia are utilized to produce biomaterials for packaging, textiles, leather alternatives, automotive components, insulation, and fire protection. These materials are renewable, degradable, and have significant innovation potential [49].

Bio-polyethylene (Bio-PE), bio-polypropylene (Bio-PP), and bio-poly(ethylene terephthalate) (Bio-PET) are developed for packaging, durable goods, and electronics, mimicking the properties of petroleum-based plastics while reducing their carbon footprint [44].

Bio-based materials are widely used in food packaging, shopping bags, and containers, offering improved sustainability and options for recycling or composting [44,45,46,47,48].

Bio-based fibers and polymers are utilized in clothing and textiles, offering biodegradable, renewable alternatives to synthetic fabrics [46,48,49,50]. Items such as disposable cutlery, bowls, and straws, as well as insulation and automotive components, are increasingly made from biobased materials [45,46,49].

Bio-based materials can also significantly reduce greenhouse gas emissions compared to their fossil-based counterparts, particularly in targeted applications such as packaging and textiles [47,48,52]. These materials are suitable for recycling, composting, and energy recovery, which supports a circular economy and reduces landfill waste [46,47,52].

4.2. Dealcoholized Grape Pomace as an Enhancer or Filler in Bio-Based Materials

Despite its high availability and industrial potential, only a limited number of studies over the past decade have investigated the use of DGP or grape pomace-derived materials as fillers or enhancers in bio-based materials. However, all available studies report significant improvements in properties such as thermal stability, heat resistance, and overall performance of the resulting biocomposites.

Auriemma et al. [53] examined the incorporation of a grape pomace extract (GPE), along with other phenol-based additives such as tannic acid (TA) and lignocellulosic biomass (LC), into poly(3-hydroxybutyrate) (PHB), a biodegradable polymer known for its limited mechanical performance and narrow processing window. Their results demonstrated that these natural additives significantly improved the thermal resistance of PHB, reduced its degradation during melt processing, and preserved its molecular weight. Rheological analysis revealed a slower viscosity decay in doped samples, indicating that LC functioned as a heterogeneous nucleating agent, which promoted crystallization during cooling and potentially mitigated physical aging. This study highlights the potential of grape pomace-derived additives as sustainable and functional stabilizers for bioplastics, such as PHB, offering an eco-friendly alternative to synthetic polymer stabilizers.

Expanding on these findings, similar improvements in thermal and mechanical performance have been observed with other agro-industrial residues, such as sugarcane bagasse and spent grain from beer production, incorporated into polymer matrices like PLA, polypropylene (PP), and high-density polyethylene (HDPE) [54,55,56,57,58]. These natural fillers typically enhance thermal stability, promote crystallinity, and improve resistance to thermal degradation and aging. Such improvements are often attributed to enhanced interfacial adhesion between the fibers and the polymer matrix, particularly when compatibilizers or chemical modifications are employed to improve compatibility. DGP exhibits similar reinforcing behavior, and its wide availability contributes to a reduction in the required polymer content, thereby increasing the sustainability and cost-effectiveness of the resulting biocomposites.

In terms of direct applications, Gowman et al. [59] explored the development of biocomposites using bio-based poly(butylene succinate) (BioPBS) reinforced with DGP via melt extrusion and injection molding. Composites containing up to 50 wt% DGP were produced, with specific formulations compatibilized using in situ synthesized maleic anhydride-grafted BioPBS (MA-g-BioPBS). The incorporation of DGP significantly improved both flexural and impact strength, with the 57:40:3 BioPBS/GP/MA-g-BioPBS blend showing the best overall performance, achieving increases of 28.4% and 59% in flexural and impact strength, respectively, compared to neat BioPBS. Additionally, the heat distortion temperature increased by 14.3%, and DGP acted as a reinforcing phase that enhanced the material’s mechanical integrity. Scanning electron microscopy revealed improved interfacial adhesion in compatibilized samples, while thermogravimetric analysis confirmed the thermal stability of DGP under processing conditions.

More recently, interest has emerged in the development of bioactive laminated composite films incorporating graphene-based polyethylene (GPE). Vázquez et al. [60] developed bioactive laminated films based on bacterial cellulose (BC) and chitosan, enriched with GPE as an antioxidant and glycerol as a plasticizer, targeting applications in sustainable food packaging. Formulations were systematically varied to evaluate their mechanical and thermal properties. The results indicated strong interactions between components, leading to improved strength and flexibility. Tensile strength values ranged from 16.92 to 32.71 MPa, and films with GPE showed up to a fourfold increase in elongation (from 2.33% to 8.63%) compared to control samples. Puncture resistance also improved with the addition of GPE and glycerol. When applied as separators for Havarti cheese, the films effectively reduced lipid oxidation by 67.3% after 60 days of storage while maintaining antioxidant activity. These findings support the use of GP-derived components in biodegradable, active packaging solutions that align with the principles of the circular economy.

Several authors have also concluded that the GPE imparts antioxidant properties to films, which is beneficial for food packaging applications by delaying oxidation and extending shelf life [61]. The integration of pomace results in more compact and well-bonded film structures, as confirmed by microscopy and spectroscopy analyses [62].

4.3. Incorporation of Dealcoholized Grape Pomace in Biodegradable Plastics

Incorporating DGP or materials derived from grape pomace into biodegradable plastics represents an emerging strategy to improve the sustainability and functionality of packaging materials.

In 2023, the Science Learning Hub [63] reported on the development of biodegradable vine net clips made from DGP, proposed as a sustainable alternative to conventional plastic clips used in vineyards. Conducted by Scion’s Biopolymers and Chemicals division, the project addressed a primary environmental concern, i.e., the estimated 16.8 million plastic clips used annually in New Zealand vineyards, which are rarely collected and often accumulate as persistent microplastic waste. The bioplastic composite was formulated by blending PLA with dried grape pomace, resulting in a material with sufficient mechanical strength for vineyard use and enhanced biodegradation compared to PLA alone. According to the authors, the vine clips biodegrade more rapidly, offering an eco-friendly solution for single-use applications in viticulture and demonstrating a tangible step forward in achieving circular bioeconomy objectives.

This study demonstrates the feasibility of using DGP as a functional filler to enhance the mechanical and thermal performance of biodegradable polymer composites, supporting the design of more sustainable materials.

More recently, Titone et al. [64] explored the incorporation of dried and ground grape pomace into the commercial biodegradable polymer blend Mater-Bi (MB)—a mixture of PLA and poly(butylene adipate-co-butylene terephthalate) (PBAT)—to improve its properties and sustainability. The study developed and characterized biocomposites containing 10% and 20% DGP, assessing their mechanical, chemical, and degradation behavior compared to neat MB. The addition of DGP enhanced the antioxidant properties of the biocomposites and modified their rheological behavior, particularly increasing the complex viscosity at low frequencies. A modest improvement in elastic modulus and crystallinity was also observed. Soil degradation tests indicated an accelerated weight loss at higher GP content, suggesting enhanced biodegradability. NMR analysis further revealed compositional changes in PBAT during degradation, including an increase in terephthalic acid content. This work highlights the potential of grape pomace as a functional filler that can boost both the performance and environmental sustainability of biodegradable plastics.

Beyond DGP, other by-products obtained after dealcoholization, drying, and screening—such as GS, grape seeds, and grape seed flour—can also be used as additives or reinforcements in biopolymer films and foams. These materials are intended to enhance mechanical, antioxidant, and barrier properties while promoting environmental compatibility, and they have been investigated in the development of biodegradable plastics (

Table 4. Additional examples of DGP-derived components incorporated in biodegradable plastics.

Example/Material Type	DGP Component	Biodegradable Matrix/Polymer	Key Properties/Findings	References
Starch-based foams with grape stalks	Grape stalks (from pomace)	Cassava starch	Good morphology, complete biodegradation in 7 weeks, suitable for food storage with low moisture content	[65]
Biodegradable spoons with grape flour	Grape flour (from grape pomace)	Proso millet, wheat, xanthan, palm oil	High strength, improved antioxidant activity, enhanced nutritional profile	[66]
Packaging films with grape seed lignin	Grape seed lignin (from pomace)	PHB/PHA blend	Improved gas barrier, antioxidant activity, enhanced biodegradability, non-toxic degradation products	[67]

). GS can be effectively used as fillers in cassava starch-based foams, integrating well without causing agglomeration or impairing foam structure. These foams are fully biodegradable within seven weeks and are suitable for packaging low-moisture food products [65].

Grape seed flour has been applied in the production of biodegradable cutlery. The resulting spoons provide a sustainable alternative to plastic utensils, combining structural strength with added nutritional and health benefits. Specifically, the flour enhances the antioxidant activity and improves the nutritional profile of the final product [66]. In another application, grape seed lignin has been incorporated into polyhydroxyalkanoate (PHA/PHB) films to improve their antioxidant capacity, gas barrier performance, and biodegradability. These films also show improved decomposition rates and yield non-toxic degradation by-products [67].

Grape pomace-derived materials consistently demonstrate rapid and complete biodegradation in soil or compost, with no formation of recalcitrant or toxic residues. Additionally, components such as lignin contribute to increased tensile strength, improved gas barrier properties, and overall durability of biopolymer films and foams [65,67]. They also exhibit significant antioxidant activity, which can extend the shelf life of packaged foods and enhance their nutritional value [66].

Starch-based foams made with GS and PHA/PHB films containing grape seed lignin have shown promise for packaging foods—especially those with low moisture content—and for extending the shelf life of fruits such as grapes. While these positive results are promising, large-scale adoption remains limited due to production costs, variability in agro-waste availability, and the need for further optimization of mechanical and functional properties [68].

Continued research is essential to refine formulations and processing techniques, thereby maximizing the benefits of incorporating grape pomace while ensuring economic feasibility and scalability.

5. Environmental Benefits of Incorporating Dealcoholized Grape Pomace in Bio-Based Materials

Incorporating DGP into bio-based materials offers several environmental benefits, primarily by transforming agricultural waste into valuable, sustainable products. This approach reduces reliance on fossil-based plastics, lowers greenhouse gas emissions, and supports the development of biodegradable materials. Using grape pomace, a by-product of the wine industry, also helps manage large volumes of seasonal agricultural waste, converting it into a functional material rather than waste destined for landfill or incineration [69]. Grape pomace can be converted into porous carbons and fibers for use in biocomposites, superhydrophobic coatings, and biodegradable films, adding value to this waste stream [70].

Replacing petroleum-based plastics with grape pomace-based biocomposites significantly reduces the global warming potential, fossil resource use, and terrestrial acidification, primarily when clean energy is utilized in the processing [68].

Life cycle assessments show that incorporating DGP or DGP-derived materials into biocomposites lowers greenhouse gas emissions and fossil resource scarcity compared to both sugarcane-based and fossil-based polyethylene [71]. Bio-based polymers derived from grape pomace and other agro-wastes have a lower environmental footprint compared to synthetic plastics, as they are renewable, biodegradable, and contribute to reducing plastic pollution.

6. Challenges and Limitations

A primary challenge in valorizing DGP or SSGP lies in its inherent variability in composition. This variability stems from diverse factors, including the grape variety, specific viticultural practices, the climatic conditions of the vintage year, the winemaking process itself, and the subsequent dealcoholization method (e.g., steam distillation vs. leaching). As a result, general extraction or processing techniques often yield inconsistent outcomes in terms of polyphenol profiles, fiber characteristics, or other target compounds. This necessitates dedicated studies to adapt and optimize these techniques for specific streams, moving beyond one-size-fits-all approaches to ensure consistent product quality and yield. The scaling up of valorization processes and the management of supply chain logistics present considerable practical challenges, particularly for companies that are typically distilleries. These facilities are often not equipped or designed for the sophisticated downstream processing required to produce pharmaceutical raw materials or high-purity food ingredients. Investment in new equipment, specialized personnel, and robust quality control systems is substantial. Moreover, distilleries may lack the necessary certifications (e.g., Good Manufacturing Practice, or GMP) to access high-value markets, posing a significant barrier to realizing the full economic potential of GP-derived products. Ensuring economic viability and cost competitiveness is another critical hurdle, even though distilleries are often strategically located in large wine-growing regions, which can minimize their carbon footprint and reduce the costs associated with collecting fresh grape pomace. The processes involved in drying, extracting, purifying, and stabilizing valuable compounds from DGP or SSGP can be energy-intensive and require significant capital investment. The final products must then compete in markets where established alternatives already exist, meaning valorization pathways must be not only technically feasible but also economically viable to justify the investment and operational costs. Finally, regulatory and standardization hurdles significantly impact the commercialization of SSGP-derived products. There is often a lack of specific regulations or established quality standards for novel ingredients extracted from SSGP, such as defined polyphenol extracts or specialized dietary fibers. This regulatory ambiguity creates uncertainty for both producers and consumers, complicates international trade, and slows market acceptance. Navigating the complex approval processes for food additives, novel foods, or active pharmaceutical ingredients requires substantial effort and investment, often acting as a deterrent for smaller enterprises or those new to these regulated sectors [72,73,74].

7. Emerging Research and Innovations

7.1. Nanocellulose Extraction from Grape Pomace

Cellulose is a natural, biodegradable biopolymer made up of β-anhydro-D-glucose units. While traditionally sourced from forest wood, agro-industrial by-products like fruit peels and husks are now recognized as valuable sources of cellulose. Recycling these materials can significantly reduce the environmental impact of food waste in agricultural and industrial activities [75].

Agro-industrial wastes offer low-cost and sustainable options for nanocellulose due to their consistent availability. This approach not only helps minimize disposal pollution but also promotes economic viability [75].

The extraction of cellulose and nanocellulose typically involves several steps, including pre-treatment, purification, acid hydrolysis of amorphous regions, and mechanical treatment to achieve nanoscale sizes. Acid hydrolysis and mechanical methods are widely used in industrial recovery [75].

Extraction techniques range from conventional methods with toxic chemicals like sodium hydroxide and sulfuric acid to newer approaches that aim for higher purity cellulose. Pre-treatment steps, such as hot water washing, are essential for quality recovery but are often neglected in reports [75].

Newer, more environmentally friendly techniques are being developed and discussed. In

Table 5. Newer and environmentally friendly extraction techniques. Adapted from Picot-Allain and Emmambux [75].

Extraction Method	Description	Advantages	Limitations
Enzyme-assisted extraction	Uses enzymes to produce cellulose nanofibrils from sources like sugar beet pulp.	Reduces water consumption; avoids chemical pre-treatments.	Enzyme activity can be influenced by temperature, pH, and secondary metabolites present in agro-industrial waste.
High-pressure homogenization	Forces cellulose slurry through a nozzle under high pressure to isolate nanostructures.	Eco-friendly, efficient, no need for organic solvents.	Clogging due to insoluble cellulose requires pre-treatment, as well as increased investment and training.
Ultrasonication	Applies ultrasonic waves to modify the morphology of nanocellulose.	Higher power leads to individualized nanofibrils with uniform width.	Not explicitly mentioned, but results can vary with power settings.
Steam explosion	Combines mild acid treatment, steam explosion, and ultrasonication to produce fibrillar nanocellulose.	Low capital cost, low energy demand, and environmentally friendly.	Limited selectivity—cannot specifically recover nanocrystals or nanofibers.
Supercritical CO2 and cold plasma extraction	Emerging green technologies for cellulose extraction.	Potentially green alternatives.	Cold plasma lacks sufficient scientific validation for the extraction of agro-industrial nanocellulose.

, we summarize some of them.

The physico-chemical properties of nanocellulose from different sources need to be characterized. Nanocellulose exhibits enhanced properties compared to micro- and macrocellulose, including an improved fiber–matrix interface and good dispersion in matrices. Nanocellulose suspensions are transparent due to their smaller and homogeneous fiber size. Important properties evaluated include the crystallinity index and thermal stability. Techniques such as X-ray diffraction (XRD), ¹³C nuclear magnetic resonance (NMR) spectroscopy, and infrared (IR) spectroscopy are used to assess crystallinity, with XRD being the most commonly employed method. Recovered nanocellulose typically exhibits an increase in crystallinity index and a higher thermal decomposition temperature compared to the raw source material [75].

Nanocellulose’s abundance, non-toxic nature, mechanical properties, and biodegradability make it attractive for various applications. Some of the applications are summarized in

Table 6. Nanocellulose applications. Adapted from [75].

Application Area	Nanocellulose Use
Cosmetics	Nanocellulose suspensions exhibit optical properties similar to those of nano-TiO2 particles, which are used in concealers and sunscreens.
Drug Delivery/Medical Applications	Nanocellulose films serve as wound dressings, inhibiting bacterial growth, particularly when combined with honey. Nanocellulose-alginate is utilized in 3D printing for personalized dressings and serves as a potential carrier for ions such as calcium.
Food/Biodegradable Plastic	Acetylated nanocellulose films exhibit reduced solubility in non-aqueous food systems or during dry storage. Starch–nanocellulose biocomposites are biodegradable and suitable for use in food packaging. Chitosan-oxidized nanocellulose films enhance strength, moisture barrier properties, and thermal stability. Nanofibrillated cellulose biocomposites provide high tensile strength and modulus for short-life packaging applications.
Green Tire Tech/Rubber Compounding	Rice husk nanocellulose composites reduce rolling resistance, resulting in lower fuel use and emissions. Nanocellulose crystals improve rubber’s tensile strength, stress, and elongation at break.

.

Extensive grape pomace produced from red wine-making can seriously pollute the environment and represents a waste of resources. Although active constituents, such as polyphenols or vitamins, are sometimes extracted, much of the grape pomace, rich in cellulose, is often treated as waste [76].

An eco-friendly method for extracting Cellulose Nanocrystals (CNCs) from grape pomace can be achieved using a simple and environmentally friendly deep eutectic solvent (DES). The green DES used had a composition of lactic acid and choline chloride in a 2:1 molar ratio. The extraction process involved pretreating crushed grape pomace to remove impurities, lignin, and hemicellulose, resulting in cellulose. This cellulose is then hydrolyzed using the DES. A key advantage of DES is its eco-friendliness and ease of preparation. The components of the DES (lactic acid and choline chloride) and ethyl acetate used for separation can be recycled, offering a sustainable and straightforward preparation method [77]. The extracted CNCs successfully obtained are rod-like crystals with an average length of 241.5 ± 45.3 nm and a diameter of 22.0 ± 3.9 nm. They show higher crystallinity (95.2%) than the original cellulose (89.6%), indicating the successful removal of amorphous regions. FT-IR and electric conductivity titration confirmed the presence of carboxylic acid groups (0.63 mmol/g) on the CNC surface, resulting from esterification with lactic acid. The surface-modified CNCs demonstrated good thermal stability and excellent dispersibility in water, remaining stable for at least 24 h [76].

A study was conducted to evaluate different methods for extracting nanocellulose, specifically cellulose nanofibers (CNFs), from yerba mate sticks (YMSs). The study successfully extracted nanocellulose (CNF) from YMSs using mild chemical treatments and steam explosion. The results demonstrated that the treatments effectively removed amorphous components, such as lignin and hemicellulose, leading to an increase in the crystallinity index of the samples. The use of both alkaline treatment and steam explosion favored the isolation of cellulose crystals, resulting in the highest crystallinity in the YMS-ASBHS sample. TEM and AFM analyses confirmed the isolation of nanocellulose in all treated samples, with the YMS-ASBHS and YMS-SBHS samples exhibiting better morphology and size characteristics, suggesting that steam explosion facilitates the removal of amorphous components. Notably, the study found that CNF could be obtained from YMS even without the alkaline treatment step (YMS-SBHS), suggesting a potential route for reducing processing steps and minimizing liquid waste generation [77].

Another angle is the possibility of utilizing wine industry wastes as a nutrient source for producing bacterial cellulose (BC) instead of using a costly commercial medium, such as the standard Hestrin–Schramm (HS) medium [78]. In the study by Ogrizek et al. [78], it was concluded that white grape pomace is a more suitable substitute for expensive commercial glucose than red grape pomace for producing bacterial cellulose. Using white pomace as a substitute carbon source resulted in a significantly higher yield and almost five times higher water-holding capacity, along with greater flexibility compared to BC produced in standard HS medium. While red grape pomace did produce BC, the resulting films were brittle. BC produced from red pomace media could be valuable for applications requiring fragmented, highly porous particles, such as in the food industry. However, white pomace BC shows greater potential for broader applications in sectors such as textiles and biomedicine, including uses such as wound dressings, hygienic face masks, and carriers for active ingredients [77].

7.2. Biochar and Activated Carbon from Residuals

As mentioned before, grape production and wine industry operations generate significant biomass residues, which are often treated as waste due to high transportation costs and low demand for by-products. Open burning, a standard disposal method, harms the environment [79].

Thermochemical conversion technologies can process biomass closer to harvest sites, improving transportation efficiency and producing valuable bio-products. Distributed-scale systems are being developed for this purpose; however, knowledge gaps exist regarding their outputs and integration into existing supply chains, posing investment risks [79].

There are few studies on thermochemical conversion of grape and wine by-products, making it necessary to compare these systems with those for forest biomass and other sources.

The study conducted by Anderson et al. [79] characterizes the producer gas, biochar, and activated carbon produced by a 700 kg h⁻¹ prototype gasification system (TEA) and a 225 kg h⁻¹ pyrolysis system (BSI) using coniferous sawmill and forest residues. The goal was to understand the products from distributed-scale thermochemical conversion systems for forest biomass, which are not widely deployed or well-characterized in this sector [79]. (i) The gas from the TEA gasifier had a higher energy content than the gas from the BSI pyrolysis system. For the TEA system, gas from sawmill residues averaged 12.4 MJ m⁻³, and gas from forest residues averaged 9.8 MJ m⁻³. Gas from the BSI system averaged 1.3 MJ m⁻³ for mill residues and 2.5 MJ m⁻³ for forest residues. (ii) Biochars from both systems showed similar particle size distributions and bulk density but varied in pH and carbon content. (iii) Biochars from both systems were successfully activated using steam activation, achieving BET surface areas within the range of commercial activated carbon [79].

Distributed thermochemical conversion systems can help meet operational needs in wood product manufacturing, including waste disposal, heat production, power generation, and the creation of value-added products. The gas and biochar outputs from the studied systems can produce heat, electricity, and various marketable products. However, uncertainties remain [79].

Gale et al. [80] investigated how hydrothermal carbonization (HTC) and slow pyrolysis (SP) produce distinct biochar precursors from corn stover, with HTC facilitating more efficient biomass breakdown at lower temperatures. HTC biochars contain more oxygen-based surface functional groups. The preparation method significantly influences the properties of activated carbon (AC); AC from corn stover and HTC biochars exhibit higher surface areas and better vanillin adsorption compared to AC from SP biochars. While surface area is important, pore structure and surface functional groups also impact adsorption performance. Gale et al. [80] also suggest that AC from corn stover could be as effective as that from HTC and SP biochars, indicating that the additional biochar synthesis step may not be necessary for producing AC adsorbents for phenolic compounds.

The study by Gonçalves et al. [81] demonstrates that Brewer’s Spent Grain (BSG) and Brewer’s Surplus Yeast (BSY) can be effectively utilized as raw materials to produce value-added products, such as granular activated carbon (GAC) and bio-oil, via pyrolysis and CO₂ activation. The implementation of this reuse strategy can provide significant benefits by generating valuable products, creating jobs, and addressing pollution issues associated with brewery residues.

7.3. Integration with Other Agri-Food Waste Streams

The agri-food sector generates significant waste due to inefficiencies in the supply chain, contributing to environmental degradation and greenhouse gas emissions, which account for 19–29% of total emissions. About 25% of resources are used to produce food that is lost or wasted. The improper disposal of organic waste, particularly from processed fruits and vegetables, poses substantial economic and environmental challenges [82].

According to the same author [82], utilizing food waste through a biorefinery approach can help achieve sustainable development. This concept integrates biomass conversion processes to produce fuels, power, and other valuable chemicals. By refining agro-industrial by-products, essential nutrients can be extracted, enabling market flexibility. By-products from the processing of tomatoes, olives, grapes, and apples are rich in health-promoting bioactives. For example, tomato waste, which accounts for 5 to 19% of the processed mass, contains carotenoids, polyunsaturated fatty acids, and pectin. Olive oil production can result in 30% waste, with olive pomace still containing valuable nutrients. Grape pomace also provide antioxidant-rich residues.

An Integrated Biorefinery Model could merge olive and grape pomace, utilizing supercritical CO₂ extraction to obtain oils, which can be used in nutraceuticals and biodiesel production. Subsequently, the solid residue can then be utilized for biogas production through anaerobic digestion. Overall, integrated biorefineries can mitigate the environmental impact of food waste while generating high-value products and energy, promoting more efficient use of diverse agri-food processing wastes [82].

7.4. Smart Materials and Responsive Composites

Smart materials can undergo significant changes in their properties under controlled conditions, enabling them to detect and respond to stimuli for beneficial effects. They demonstrate “smart behavior” by reacting reliably to physical or chemical inputs. Recent advancements include self-healing components, sensing materials, and shape-changing substances, with a focus on intelligent bio-based composites utilizing natural biopolymers, such as cellulose, which can be enhanced with inorganic elements to achieve dynamic responses. Applications span biomaterials, robotics, and artificial muscles.

According to Ramakrishnan et al. [83], two-dimensional smart membranes are gaining traction for their roles in separation processes, healthcare, and environmental remediation, showcasing capabilities such as pressure transduction and energy harvesting. Advancements in smart biodegradable food packaging utilize plant extracts, such as anthocyanins, for quality monitoring and shelf-life enhancement, alongside innovative photoactivated materials. Smart materials are paving the way for improvements in health and well-being, facilitating innovations in medical applications, from physiological monitoring to minimally invasive surgery. Their development is crucial for advancements in wireless communication, smart buildings, and sustainable design, using materials such as piezoelectric and thermochromic options that enhance energy efficiency.

Smart hybrid Nickel–Titanium (NiTi) materials are increasingly used due to their smart properties. Combining NiTi alloys creates a “smart material” with smart alloy properties. NiTi alloys benefit various sectors, with a primary focus on automotive applications, including suspension systems, wing mirrors, and safety lock units. NiTi can also be used in shape-memory alloys for the automotive sector.

8. Industrial and Market Perspectives

8.1. Current Commercial Initiatives and Case Studies

The valorization of winemaking by-products and waste presents significant economic, social, and environmental advantages, often yielding higher financial returns than wine production. Grape pomace, in particular, has proven economically efficient for valorization. Rising waste disposal costs in the EU emphasize the need for viable recycling solutions. Economically, waste valorization can reduce management costs, sustain jobs, and enhance productivity by leveraging by-products like anthocyanins for use in food, pharmaceuticals, and cosmetics. This boosts income for wine producers and promotes high-performance products. Socially, benefits include improved agricultural management, adherence to European labor standards, job creation, and enhanced quality of life in rural areas. Environmentally, it promotes responsible management of emissions and resource use, reduces waste, and enables the utilization of by-products as fertilizers, which in turn protects the environment and creates job opportunities [84].

In the article “The Exploitation of By-Products in a Waste Management Process”, the authors address the universal contemporary challenge of sustainability within the global economic, social, cultural, and physical environment. They highlight the critical role of interdisciplinary Supply Chain Management (SCM) and its evolution into Sustainable SCM (SSCM) and Green SCM. The wine industry is identified as a fertile ground for developing multidisciplinary collaborations and applying innovative entrepreneurship practices in both forward and reverse agrifood chains [85]. The paper explicitly studies the exploitation of opportunities arising from wine production and waste management in this new environment. It presents a start-up business plan developed through a collaboration between the Agricultural University and the Harokopio University of Athens, Greece. The focus is on a wine waste management company located on the island of Crete, Greece, demonstrating how challenges can be transformed into opportunities for innovation and more efficient use of by-products and wastes.

The study’s methodology involved an action research framework and a business plan goal. The location, Kissamos province in Crete, was chosen due to its tradition in viticultural farming, wine production, and historical innovative capability. Data were collected through interviews with managers of potential supplier wineries and potential customer pharmaceutical and food companies. Secondary data provided technical information for the company’s setup and costs. Analytical tools used included PESTEL and SWOT analyses. A technical and financial analysis, including profit and loss (P/L) evaluation and economic performance indicators, was also conducted.

The start-up company in Kissamos, West Crete, will focus on elaborating wineries’ by-products, specifically pomace, to produce polyphenols. Pomace is a significant by-product of Greek wineries. The company’s potential suppliers are seven large wineries identified as having medium-level sustainable orientation (“unexploiters”) with potential for future adoption of sustainable practices. Potential customers are from the food, cosmetics, and pharmaceutical industries, with an interest in polyphenols derived from grapes. The SWOT analysis revealed key factors (

Table 7. SWOT analysis, retrieved from Malindretos et al. [85].

Strengths	Weaknesses
- Crete’s tradition in grape farming	- High dependence on supplier wineries and grape production volumes
- Educated managers	- Absence of institutional support for green initiatives
- Differentiated final product (polyphenols) aligned with sustainability trends	- High investment costs
- Potential long-term agreements with customers	- Lack of specialized employees
Opportunities	Threats
- Growing global awareness of qualitative, nutritious food and environmental issues	- Global economic crisis
- No current competitors in this niche
- High entry barriers due to required expertise and investment
- Potential future financial support from EU funds

).

The financial evaluation of the start-up project yields positive results, with initial infrastructure costs estimated at over EUR 1.9 million and annual operational costs projected to exceed EUR 1.58 million. By utilizing pomace from suppliers, the company can produce 656.25 tons of polyphenols annually, with a forecasted first-year revenue of EUR 1,968,750, potentially increasing to over EUR 2 million within five years. Key financial indicators suggest that the investment is sustainable. The study highlights that entrepreneurship is driven by innovative behavior, appropriate infrastructure, and collaboration between academia and industry, which can enhance sustainability in the wine sector. Partnerships among local stakeholders are essential for developing sustainable solutions and creating job opportunities. The role of universities and authorities in promoting sustainable practices is crucial for overall well-being.

8.2. Market Potential for GP-Derived Materials

Although most grape pomace could be composted and returned to vineyards to help close the carbon cycle, this practice is not widely implemented. At the same time, there is growing consumer demand for natural compounds over synthetic alternatives, as well as an increasing focus on the sustainability of agricultural practices. This context highlights a vast array of potential applications for the bioactives found in grape pomace. Despite this potential, no prior assessment of the market potential for value-added uses of grape pomace had been conducted (

Table 8. Alternative bioactive applications and market potential. Adapted from Dwyer et al. [86].

Application	Key Details/Benefits
Composting	Currently, the majority of grape pomace used in Ontario and B.C. is composted on-site and recycled into the vineyard. It has an initial carbon-to-nitrogen (C: N) ratio of approximately 27:1, which is within the optimal range (25:1 to 35:1) for composting. Composting increases the nitrogen content (e.g., to 2.35 wt%), which is beneficial for vineyard growth. Using only composted grape pomace as the sole nitrogen source is neither feasible nor economical; supplemental fertilizer is required. Nitrogen from compost is considered “slow-releasing”, and improper distribution year-to-year could lead to detrimental nitrogen overabundance.
Functional Foods	It can be used as a functional food ingredient due to its high fiber and phenolic content. Consumer acceptance studies have been conducted for products incorporating grape seed flour or grape pomace skins.
Food Processing	Grape pomace can be used for biosurfactant production, utilizing glucose for lactic acid. It can be added to food products for consistency and texture. Bioactives, such as antioxidants from pomace, can be added internally to preserve food and are particularly preferred over synthetic antioxidants in meat products. Glucose can be used to produce Pullulan, which can be used as a food additive for texture and low-calorie bulk.
Cosmetics	Antioxidants and oils from grape pomace can be used topically. Grape seed oil, rich in linoleic acid, is beneficial for maintaining skin moisture, aiding in the healing of sunburns, and potentially reducing the appearance of acne. Vitamin E extracted from grape seeds is also effective when applied topically.
Pharmaceutical/Biomedical	Pullulan has various applications in this field.
Supplements	Products like Bioflavia, an organic dried red grape skin powder, are already being sold as supplements. Grape seed oil is also available as a supplement.

) [86,87].

The article by Dwyer et al. [86] assesses the market potential of red grape pomace alternatives, highlighting existing products. The estimated market potential for red grape skins produced in Ontario and British Columbia (B.C.) in 2011 was approximately CAD 499 million for Ontario and CAD 185 million for B.C., assuming 100% utilization as supplements. For grape seed oil, the potential was over CAD 5 million combined from both provinces. These numbers reflect theoretical market values based on complete utilization and do not account for factors such as composting or extraction costs, meaning the actual potential would likely be lower. Despite this, they indicate significant annual production of pomace and potential commercial uses. Current primary uses involve composting, but there are opportunities in functional foods and supplements. Further research is necessary to assess economic viability and explore alternative applications, as grape pomace is expected to remain primarily composted until proven otherwise.

Recently, innovative uses have been found for grape pomace, indicating its increasing market potential. Dos Santos Silva et al. [87] discuss the technological potential of grape pomace for use in the meat industry. The text addresses the compounds of interest within grape pomace and elucidates the challenges associated with their application in meat products. The adoption of nano- and microencapsulation technologies, along with the implementation of active packaging as carriers for grape pomace extracts, significantly enhances their application in meat and meat products. These technologies, whether applied individually or in combination, facilitate the controlled release of bioactive compounds during storage while also masking undesirable flavors associated with phenolic compounds.

In addition to the technological advancements, the incorporation of grape pomace within the meat industry aligns with the growing demand for natural additives. It aligns with the United Nations’ Sustainable Development Goals. This practice mitigates environmental impacts and enables the extraction of high-value molecules from industrial waste.

The work of Manso et al. [88] examines an integrated biorefinery approach that aims to maximize the utilization of white grape pomace (WGP) through a combination of hydrothermal and organosolv treatments, followed by solid-state fermentation (SSF). The hydrothermal pretreatment process was optimized to enhance sugar extraction, achieving a concentration of up to 80.94 g L⁻¹ of reducing sugars, which can be utilized as a substrate for microalgae cultivation. The organosolv treatment facilitated the selective recovery of polyphenols and lignin, with the highest yield of polyphenols (2.27 g kg⁻¹ dry weight) being obtained at a temperature of 150 °C. Additionally, a lignin yield of 34.72% was achieved at 200 °C. The residual solid fractions were subsequently subjected to solid-state fermentation using the fungi Aspergillus oryzae, Neurospora intermedia, and Rhizopus oryzae, resulting in a noteworthy increase in protein content, with A. oryzae achieving a protein content of 17.6% on a dry weight basis. This multi-step integrated approach demonstrates a scalable and sustainable strategy for converting WGP into multiple high-value bio-products, thereby advancing the principles of the circular economy within the food sector.

As previously mentioned, the main solid by-products and waste from winemaking are grape pomace (GP), wine lees, and grape solids (GSs). Regulations in Spain require industrial waste to be recycled, valorized, or properly disposed of to prevent environmental contamination. Traditionally, wineries have opted for disposal and paid a “polluter pays” fee. However, a significant rise in disposal fees—along with fines for unauthorized discharges that can reach EUR 30,000 to EUR 40,000—has made waste valorization a more attractive and economically viable alternative. Penalties can also include mandatory decontamination of affected areas or even prison sentences.

In this context, valorization emerges as both an environmentally responsible and cost-effective strategy. Although it mentions data from 2011, the work of Devesa-Rey et al. [89], which highlights several approaches for valorizing different winery wastes, including trimming residues, grape pomace, and wine lees, remains relevant. Their findings suggest that these strategies not only reduce the costs associated with biotechnological processes but also contribute to sustainable waste management.

Table 9. Strategies for valorizing grape pomace.

Material	Description Composition	Potential Uses and Valorisation Methods	Specific Process Notes
Grape Pomace	Lignocellulosic material is generated after pressing. Distilled grape pomace is also produced.	Source of hemicellulosic sugars (xylose and glucose).	Can be hydrolysed. Usable as a substrate for lactic acid and biosurfactant production by Lactobacillus pentosus. Mineral and organic nitrogen enhance xylose consumption.
		Production of biosurfactants and extracellular bioemulsifiers.	Lactobacillus pentosus can produce cell-bound biosurfactants and extracellular bioemulsifiers from hydrolysates. These can reduce surface tension and effectively stabilize kerosene/water emulsions. Other microorganisms can also utilize grape seed oil for the production of biosurfactants.
		Extraction of phenolic compounds with antioxidant properties.	Can use organic solvents or supercritical carbon dioxide.
		Extraction of condensed tannins.	For enology and as wood adhesives.
		Extraction of oil from grape seeds.	For the food industry.
		Production of anti-allergic substances.	Achieved through lactic acid fermentation with Lactobacillus.
		Obtaining hydrolytic enzymes and bioethanol.	Achieved through solid-state fermentation.
		Component for plant growing media.	Used after stabilization treatments like composting. Composting with animal manure can reduce phytotoxicity. Winery waste compost, including grape marc, was successfully evaluated for use as a fertilizer for crops such as tomatoes.
		Component for a high-quality, low-cost substrate for cultivating edible mushrooms.	Part of the vineyard waste is used for this.
		Improved agronomic value through vermicomposting.	Reduces C:N ratio, conductivity, and phytotoxicity. Increases humic materials, nutrients, and pH. Performs better than compost as an amendment for mining wastes.
		Natural adsorbent for metals (e.g., copper and lead).	In winery effluent pretreatment.
		A valuable source of energy and protein for ruminants.	Can be combined with vine shoots and wine lees.
		Source of microbial and human food.	Can be bioconverted by Pleurotus spp. and through solid-state fermentation, potentially combined with vineyard pruning and wine lees.

summarizes the valorization strategies proposed by Devesa-Rey et al. [89] for DGP.

9. Industry–Academia Partnerships

Policies, Subsidies, and Incentives Promoting Bio-Based Innovation

The Bio-based Industries Joint Undertaking (BBI JU) catalyzes sustainable bio-based economic growth in Europe. Established in 2014 as a public–private partnership between the European Commission and the Bio-based Industries Consortium, it supports research, innovation, and investment in bio-based industries. BBI JU aims to overcome market barriers to private investment, promoting a bio-based economy that utilizes domestic renewable raw materials for producing food, feed, chemicals, materials, and fuels. It embodies the principles of the circular economy under the Horizon 2020 initiative.

Mengal et al. [90] identify several challenges facing the European bio-based industry: (i) lack of critical mass at the European level in terms of scale, excellence, and innovation potential; (ii) the sector is fragmented, with diverse organizations and companies that have not collaborated across industries and regions before; (iii) geographical issues related to the supply of biomass feedstock; (iv) difficulty in linking advancements in bioeconomy research and innovation with commercialization and market uptake; (v) complex and substantial technology and innovation challenges in bio-based industries and value chains; (vi) struggling to set up new value chains due to the diverse range of involved players who have not worked together; (vii) potential investments and resulting knowledge are being implemented outside of Europe; (viii) the need to bridge the “valley of death” between proof-of-concept and scaling up to commercial levels.

The BBI JU aims to establish a competitive and sustainable Europe by transitioning to a low-carbon society using renewable raw materials. This initiative focuses on the local production of chemicals, materials, and fuels, fostering job creation and rural development while emphasizing sustainability and resource efficiency. Funded with EUR 975 million in public money, it aims to leverage at least EUR 2.73 billion in private investment between 2014 and 2024. It provides a stable framework for strategic collaboration between industry partners, encouraging long-term private sector investment in demonstration and large-scale projects. Its operations are managed by the BBI JU Program Office, which is overseen by a Governing Board comprising representatives from the EC and BIC. The Strategic Innovation and Research Agenda (SIRA) outlines the priority topics for annual work programs. BBI JU funds collaborative research and innovation projects, typically requiring participants from at least three different Member States or Associated Countries, across various Technology Readiness Levels (TRLs), generally ranging from TRL 3 to TRL 8 (

Table 10. Project type, acronyms, and focus from several projects [90].

Project Type	Acronym	Focus/Scope
Coordination and Support	CSAs	Address cross-sectoral challenges and support value chains through studies and networking, such as standardization and regulatory issues.
Research and Innovation	RIAs	Validate specific technologies at the laboratory and pilot levels.
Innovation	IAs	Address the entire value chain from feedstock to market applications.
Demonstration Actions	IA.DEMO	Scale up technologies to prove readiness for commercial production and demonstrate the business case.
Flagship Actions	IA.FLAG	Establish first-of-a-kind industrial-scale biorefineries by scaling up demonstrated technologies.

).

Funding levels differ by organization and project type. Universities, academic bodies, and non-profits can receive 100% funding for eligible costs in Research and Innovation Activities (RIAs), Coordination and Support Actions (CSAs), and Innovation Actions (IAs). Large industries receive up to 70% funding for Flagship and Demonstration projects, but not for Research, Innovation, and Advanced (RIA) or Commercialization and Small Business (CSA) projects. SMEs receive 100% for RIAs and CSAs and 70% for Flagship and Demonstration projects.

The benefits of a strong bio-based industrial sector for European citizens include a reduced reliance on fossil fuels, contributions to climate targets, environmentally friendly growth, greener products, significant reductions in greenhouse gas emissions, waste utilization in line with the circular economy, optimized land use, job creation, and support for regional development. Key performance indicators (KPIs) for monitoring include cross-sector connections, new bio-based value chains, industrial investments, collaborative projects, emission reductions, and the establishment of biorefineries and flagship projects. The overall impact is assessed based on socio-economic and environmental benefits. The BBI initiative aligns with the circular economy and the 2012 European Bioeconomy Strategy, focusing on sustainable biomass supply, efficient processing, innovative bio-based products, and market growth. It engages various feedstocks, including agri-based, forest-based, aquatic, bio-waste, and CO₂. Additionally, the BBI JU promotes synergies with national strategies and other EU funding programs and has launched a plan to enhance participation from underrepresented regions and stakeholders [89].

10. Final Remarks

The incorporation of DGP as a filler or additive in polymer matrices provides a substantial enhancement of mechanical characteristics, including increased tensile strength, elasticity, and flexibility, along with notable antioxidant properties. These enhancements render the resultant composites particularly appealing for sustainable packaging applications and other functional uses.

Integrating grape pomace into polymer systems has proven to be a proficient strategy for elevating the thermal properties of biocomposites. This method not only enhances heat resistance and thermal stability but also promotes sustainability by valorizing agricultural by-products, thereby reducing overall polymer consumption.

DGP in its various processed forms can be effectively utilized in the development of biodegradable plastics, enhancing their environmental credentials, mechanical robustness, and antioxidant efficacy. Such biocomposite materials show significant promise for applications in single-use items and food packaging; however, further research and development efforts are necessary to overcome commercial production hurdles and optimize the performance characteristics of these materials.

The employment of DGP in bio-based materials presents distinct environmental advantages by minimizing waste, reducing carbon emissions, and facilitating the transition to biodegradable and renewable products. This approach not only addresses the challenges associated with waste management but also contributes to the establishment of more sustainable material cycles.

Valorizing FLW presents a significant opportunity to mitigate environmental impacts. However, standardization and quality control are essential for scalable processes, which combine FLW valorization with efficient food production and emerging technologies to meet global needs.

Sustainable wine production is vital for the industry’s future, benefiting environmental, social, and economic sustainability. The sector can significantly contribute to various Sustainable Development Goals (SDGs), such as SDG 2 (Zero Hunger) through sustainable farming practices, SDG 3 (Good Health) by promoting responsible drinking, and SDG 12 (Responsible Consumption) through sustainable production and consumption. Academic literature can guide the industry in addressing sustainability challenges effectively.

11. Future Directions and Opportunities

11.1. Multidisciplinary Approaches for Material Development

Effective waste management faces challenges like inadequate funding, poor infrastructure, and limited public awareness. Traditional landfills harm the environment, while advanced thermal conversion technologies, such as gasification and pyrolysis, can be costly. Circular economy principles prioritize composting and anaerobic digestion over incineration and landfilling, as they enhance soil properties and support sustainable food systems [90].

Proposals suggest integrating multiple disciplines to tackle global food waste challenges, specifically through anaerobic digestion. Key areas include (i) techniques such as metagenomics and proteomics, which enhance the understanding of microbial processes in biogas production; (ii) utilization of nanomaterials to enhance waste treatment efficiency, reduce costs, and improve biogas output through conductive materials; (iii) optimizes anaerobic digestion processes for better efficiency; and (iv) analyzing data and predict digester performance using methods like artificial neural networks [91].

A collaborative and multidisciplinary approach, supported by robust policies, is essential for effective and sustainable food waste management worldwide. More integrated research is needed to explore these methodologies.

11.2. Advanced Functionalization and Hybrid Materials

The article by Otoni et al. [92] explores the potential of using agri-food residues, specifically food losses and waste (FLW), to develop next-generation bioplastics and advanced materials within the context of a circular bioeconomy. It highlights the environmental impacts of food side streams, emphasizing the importance of reducing food loss and waste (FLW). The distinction is made between food loss, which occurs before retail, and food waste, often resulting from consumer behavior. Approximately 14% of food is lost before retail, particularly in cereals and pulses. The valorization of FLW involves transforming these residues into high-value materials, rather than returning them to food, by utilizing methods such as polymerization and biosynthesis to produce bioplastics and other materials.

Various building blocks derived from food loss and waste (FLW) are explored: (i) Monomers and modified molecules, which include hydroxy acids, epoxides, fatty acids, and lactic acid sourced from fruits, vegetables, and oils, are usable for producing polymers such as polyesters and polyurethanes. D-Limonene from citrus peels is a notable monomer, although challenges remain in its polymerization. (ii) Soluble biopolymers (pectin, starch) and insoluble ones (lignin) can be extracted for applications in films, coatings, and medical devices. Lignin enhances cellulose’s wet strength, enabling the creation of bioplastics, while proteins like gelatin are functional in medical wearables. Additionally, nanocelluloses from plant waste and chitin nanocrystals from crustacean shells can be utilized, along with biogenic silica microparticles obtained from pineapple peels.

FLW composition influences film formation, with each component contributing unique properties. Films made from carrots, parsley, and cauliflower show potential but may require reinforcement to achieve optimal strength.

Manufacturing processes significantly affect material properties. Utilizing FLW can lower production costs through methods such as spinning, casting, and 3D printing. Mycelium-based products are also emerging.

11.3. Integration into Local Circular Economy Models

The growing interest in sustainability within the wine industry highlights the increasing consensus that circular economy solutions are essential for achieving the United Nations’ Sustainable Development Goals (SDGs). By implementing circular economy strategies, wine production processes can improve both environmental and economic sustainability. Key components of these strategies include waste valorization and industrial symbiosis.

However, a gap exists between theoretical sustainability strategies and their practical implementation in the wine industry. This gap can be attributed to several factors, including the substantial investments of time, resources, and technology required, financial constraints faced by smaller producers, a lack of knowledge, and difficulties in coordinating practices throughout the entire supply chain.

The review by Abbate et al. [20] identifies two main thematic areas: (i) Attitudes towards sustainability in the wine industry include drivers and barriers to adopting sustainable practices, the development of circular business models, the integration of technologies, and performance indicators. Drivers include internal values, stakeholder expectations, marketing, innovation, and competitiveness. Consumers are increasingly willing to pay more for sustainably produced wines. (ii) Wine waste valorization focuses on transforming by-products into valuable resources. This includes bioenergy from grape marc and cheese whey, biorefineries, and the extraction of bioactives from vine pruning. Other applications include grape seed oil for packaging and anthocyanins for food, cosmetics, and pharmaceuticals. Wine waste can also be processed into compost and organic fertilizer for functional foods.

Practical applications include integrating grape residues into consumer products, new extraction methods, and innovations such as WineLeather and antioxidant-rich asphalt. Economic and environmental benefits include reduced disposal costs and new revenue streams. Future research should explore technologies in vineyards, partnerships for by-product exchange, waste prevention, and the evaluation of sustainability through cost–benefit and life cycle analyses.

11.4. Alignment with UN Sustainable Development Goals (SDGs)

Sustainability is vital for the long-term survival of the wine industry. Embracing sustainable practices protects natural resources, ensures fair employment, and leverages technology to improve production quality while minimizing environmental impacts. These practices enhance wine quality by reducing chemical use, conserving water, and improving waste management. Additionally, sustainability enhances the industry’s image and tourism while lowering production costs through improved resource management.

The wine industry makes a significant contribution to the economy, culture, and local employment, while also having a positive impact on ecosystems and promoting the use of renewable energy. It engages in practices that reduce pesticide and fertilizer use, improve water quality, and enhance biodiversity.

Recognized as a key partner in the United Nations’ Sustainable Development Goals (SDGs), the wine industry supports economic growth, promotes employment and social justice, and fosters environmental preservation. It creates jobs, invests in education, and removes gender barriers, ultimately improving farmers’ incomes and quality of life. However, unsustainable wine production can harm development goals, including the use of pesticides, loss of biodiversity, excessive water use, and greenhouse gas emissions from transportation, packaging, and processing. Vineyard expansion can also lead to deforestation, soil erosion, and reduced land availability.

The study by Martínez-Falcó et al. [93] used a bibliometric analysis of the Web of Science (WoS) database. A specific search equation, incorporating Boolean operators and wildcards, identified relevant articles published between 1997 and 2022. The PRISMA statement guided article selection, narrowing 114 initial records to 107 after removing duplicates and irrelevant items. Bibliometric reviews provide a comprehensive overview, highlighting research trends, priorities, and connections between authors.

Key findings include (i) a 633.33% increase in SDG-related wine research from 2015 (3 articles) to 2022 (22 articles), mainly due to the UN’s 2015 adoption of the SDGs; (ii) main research areas such as Environmental Sciences, Green Sustainable Science, and Food Science Technology, with contributions from Horticulture and Agriculture, underscoring the multidisciplinary focus.

11.5. A Roadmap for the Valorization of Dealcoholized Grape Pomace in Bio-Based Materials: Opportunities, Challenges, and Pathways for Industrial Uptake

DGP has emerged as a promising bio-based material for biocomposites and biodegradable plastics, particularly in applications such as food packaging, agricultural tools, and single-use items. Existing studies consistently demonstrate that DGP improves mechanical performance, thermal stability, and antioxidant activity when used as a filler or functional additive. These performance gains, along with DGP’s abundant availability and compatibility with circular economy principles, position it as an attractive candidate for developing sustainable materials.

Nevertheless, despite encouraging results, the field remains in a relatively early stage and would benefit from a more application-oriented research strategy. To support industrial uptake and advance scientific development, the following roadmap identifies key research priorities.

First, DGP’s role as a sustainable filler has been demonstrated, but its practical relevance could be significantly enhanced by focusing on application-specific performance metrics. For example, researchers should evaluate barrier properties for food packaging applications, investigate aging resistance for outdoor or agricultural uses, assess biodegradability under both industrial and home composting conditions, and examine shelf-life stability for active packaging systems.

Second, greater attention must be given to the optimization of processing parameters. This includes understanding the influence of drying methods and particle size on DGP’s reinforcing capabilities, fine-tuning compatibilizer formulations to enhance interfacial adhesion within different polymer matrices, and examining how extraction or purification methods affect the final material properties.

Third, while the environmental advantages of DGP valorization are well-articulated, the economic dimension requires stronger support. We consider that conducting a robust economic feasibility analysis—factoring in drying costs, energy demands, and market competitiveness—is essential to substantiate claims of sustainable valorization and to guide investment decisions.

Fourth, the path to industrial scale-up will benefit from standardization and integration into existing manufacturing frameworks. Establishing common protocols for the collection, drying, and storage of DGP will help ensure uniform quality. Moreover, defining key performance indicators and developing scalable, industry-aligned processing techniques are critical for consistent and widespread application.

Despite its potential, several scaling challenges must be addressed to ensure the successful commercial deployment of DGP-based materials. One significant barrier is supply chain variability, as the volume and composition of DGP can vary considerably depending on grape variety, regional practices, and vintage conditions, thereby complicating efforts toward consistent sourcing and standardization. Another significant hurdle is the energy-intensive and logistically complex process of drying wet pomace, especially for small and medium-sized wineries that may lack the infrastructure for in situ valorization. Regulatory issues also pose obstacles, particularly concerning approvals for food-contact materials or classification of DGP composites under national biodegradability standards. Ultimately, a significant gap remains in market readiness and industry awareness. Many potential users are still unaware of DGP’s functional benefits, highlighting the need for demonstration projects, stakeholder outreach, and more transparent communication of performance advantages.

DGP offers strong potential as a high-performing, sustainable, and circular filler for bio-based materials. To fully realize its value, the field must evolve beyond proof-of-concept work and pursue targeted application testing, economic and environmental validation, and the resolution of technical and regulatory bottlenecks. Coordinated efforts among researchers, industry partners, and policymakers will be essential. With the proper support, DGP-based materials can make a significant contribution to the development of a circular and bio-based economy, particularly in wine-producing regions where this resource is both abundant and underutilized.