Research

Upcycling: the food by-products bioprocess wheel

June 3, 2025

100

The food by-products bioprocess wheel (FBBW) is an innovative tool designed to advance biotechnological upcycling in the fight against food loss and waste (FLW). With nearly 30% of global agricultural production lost during processing and production stages, the food industry faces urgent demands to improve environmental sustainability and resource efficiency. In response, researchers from Wageningen University and Research Centre, Universitat Autònoma de Barcelona, and the National Research Council (CNR) of Italy have developed the FBBW — a comprehensive framework recently published in Trends in Food Science & Technology (Vilas-Franquesa et al., 2024).

This strategic tool provides valuable guidance for scientists and industry stakeholders looking to implement efficient and scalable upcycling strategies for food by-products. Among the most promising sustainable extraction methods are enzymatic-assisted extraction (EAE) and fermentation-assisted extraction (FAE). These biotechnology-driven approaches enable the conversion of food industry by-products into high-value functional ingredients, offering significant advantages over conventional chemical processes. They operate under mild conditions, preserving sensitive bioactive compounds and reducing environmental impact, thereby making green bioprocessing a viable and cost-effective solution for the circular food economy.

Table of Contents

Methodology

The research team, led by Vilas-Franquesa and colleagues, employed a systematic approach to develop the FBBW. The methodology involved scrutinising successful applications of EAE and FAE technologies across different by-products documented in recent scientific literature. The wheel construction focused on the most produced fruits, vegetables, crops, and cereals globally, including sugarcane, coffee, rice, bananas, and potatoes.

The researchers categorised agro-industrial products into three main groups:

fruits,
vegetables, and
crops/cereals.

Each category underwent further sub-categorisation based on individual products. The team identified the most relevant by-products from production processes, considering proximate composition when available. Only solid and insoluble by-products were included, explicitly excluding waste waters, solvents, or other liquid waste streams from cleaning or extraction processes.

The wheel’s design follows a circular, multi-layered structure to be read from the inside out. The inner circle contains the broader categorisation, whilst subsequent circles narrow down to specific products, their by-products, and finally the targeted compounds or extraction objectives. This visual approach facilitates quick identification of upcycling possibilities for specific by-products.

Major outcomes

The FBBW successfully catalogues numerous biotechnological processes for valorising food by-products across all three major categories, revealing extensive opportunities for sustainable upcycling. The comprehensive analysis identified over 100 successful applications of EAE and FAE technologies, each demonstrating measurable improvements in bioactive compound extraction and functional ingredient production.

Fruit by-products valorisation

Fruit processing generates diverse by-products including pomace, peels, seeds, shells, and leaves, each presenting unique upcycling opportunities. The research documented remarkable outcomes in pomace valorisation, particularly with Chinese bayberry pomace undergoing mixed fermentation with multiple probiotic strains. This process successfully slowed anthocyanin degradation whilst converting flavonoids into more bioavailable flavonol aglycones, with gallic acid concentrations reaching 185 ± 0.04 mg/g (Zhu et al., 2022).

Citrus peel valorisation demonstrated exceptional results through lactic acid fermentation. Orange peels fermented with Lacticaseibacillus casei 2246 achieved the highest lactic acid concentration of 209.65 g/kg with a yield of 0.88 g/g, establishing orange peels as suitable raw material for industrial lactic acid production (Ricci et al., 2019). Grapefruit peel treatment with cellulase at 8% enzyme dosage released insoluble phenolic compounds at 14 mg/100 g, including gallic acid (42.5 mg/100 g) and ferulic acid (18 mg/100 g) (Peng et al., 2021).

The valorisation of coffee by-products yielded particularly impressive results. Spent coffee grounds treated with combined enzymatic hydrolysis using Viscozyme L and Celluclast increased total soluble matter almost eight-fold, with monosaccharide content reaching 17 g/100g and melanoidin concentration up to 72 mg/g. Additionally, caffeic acid levels increased to 2.22 mg/g (Gu et al., 2020). Alternative fermentation approaches using Lactobacillus rhamnosus increased polyphenol content to 227.3 ± 3.3 mg/g extract whilst reducing caffeine by 38% (Milić et al., 2023).

Seed valorisation presented diverse outcomes depending on composition. Black plum seeds fermented with Aspergillus oryzae achieved tannase activity of 34.4 U/g and gallic acid yields of 16.66 mg/g substrate after 96 hours at 30°C (Saeed et al., 2020). Raspberry seeds subjected to acid and enzymatic treatment showed a 101.8-fold increase in ellagic acid concentration compared to methanol extraction, with significant α-glucosidase inhibitory activity (Wang et al., 2019).

Vegetable by-products transformation

Vegetable processing generates substantial quantities of peels, leaves, stems, and roots, each requiring tailored biotechnological approaches:

potato peel valorisation emerged as particularly successful, with Rhizopus oryzae fermentation producing 0.039 g lactic acid per gram of substrate under optimised conditions (Ozer Uyar & Uyar, 2023). More innovatively, Pseudomonas aeruginosa BK25H fermentation of potato peels yielded pyocyanin and 1-hydroxyphenazine biopigments, with production increasing ten-fold upon NaCl addition (Pantelic et al., 2023);
artichoke by-products demonstrated exceptional pectin recovery potential. External bracts, leaves, and stems treated with Celluclast®1.5L achieved pectin extraction of 176 mg/g dry matter under optimised conditions (6.5% powder concentration, 10.1 U/g enzymatic activity, 27.2 hours). Subsequent treatment with various pectinases produced pectic oligosaccharides at 310.6 mg/g pectin with molecular weights of 6-14 kDa, suitable for prebiotic applications (Sabater et al., 2018; Sabater et al., 2019);
eggplant peel valorisation showcased dual functionality through sequential extraction. Initial phenolic extraction recovered total anthocyanins up to 585.30 mg cyanidin-3-glucoside/L and total phenolic content reaching 3060 mg GAE/L using cellulase treatment at 60°C (Amulya & ul Islam, 2023). Subsequently, the extracted peels underwent fermentation with Aureobasidium pullulans, producing up to 16.8 g/L of pullulan (a versatile, natural polysaccharide) after seven days, demonstrating complete by-product utilisation (Kazemi et al., 2019);
root vegetable by-products showed promising results for enzyme production. Sweet potato peels fermented with Aspergillus niger produced α-amylase with activities reaching 214.28 U/ml under optimised conditions (pH 6.5, 2% substrate concentration, six days) (Pereira et al., 2017). Onion skin waste subjected to combined cellulase, pectinase, and xylanase treatment achieved a 1.59-fold increase in quercetin extraction (Choi et al., 2015).

Crops and cereals by-products innovations

The valorisation of cereal brans revealed substantial potential for bioactive compound recovery and functional ingredient production:

rice bran fermentation with Trichoderma viride for 100 hours at 28°C released bound phenolics, with ferulic acid and p-coumaric acid concentrations reaching 5.55 mg GAE/g dry weight, significantly exceeding alkaline hydrolysis yields (Xie et al., 2021). Enzymatic extrusion of rice bran using neutrase produced feruloyl oligosaccharides exceeding 5% of bran dry weight (Deng et al., 2023);
wheat processing by-products demonstrated remarkable functional improvements through fermentation. Wheat bran fermented with Enterococcus faecalis showed a 5.5-fold increase in ferulic acid concentration, enhanced antioxidant capacity, and improved dietary fibre solubilisation (Mao et al., 2020). Wheat germ fermentation with Lactiplantibacillus plantarum produced extracts containing 20 g/kg gamma-aminobutyric acid (GABA), alongside increased concentrations of 2,3-dimethyl-1,4-benzoquinone and enhanced radical scavenging activity (Bayat et al., 2022);
sugarcane bagasse valorisation achieved significant oligosaccharide production. Solid-state fermentation with Aspergillus oryzae produced fructooligosaccharides at 7.64 g/L of extract after 12 hours (De la Rosa et al., 2020). Alternatively, enzymatic hydrolysis using endoxylanase from Aspergillus flavus generated xylooligosaccharides at 947.49 mg/g xylan, comprising xylotetrose (69.75%), xylobiose (13.17%), and xylotriose (8.37%) (Gupta et al., 2022);
soybean hull transformation demonstrated versatility in product outcomes. Fermentation with recombinant Saccharomyces cerevisiae strains produced xylitol at 8.17 g/L under oxygen-limited conditions (Cortivo et al., 2018), whilst Aureobasidium pullulans fermentation yielded polymalic acid at 0.4 g/g substrate with production rates of 0.5 g/L·h (Cheng et al., 2017). Solid-state fermentation with Aspergillus oryzae extracted phenolic compounds at approximately 0.25 g GAE/100 g hulls, significantly exceeding commercial α-amylase extraction yields (Cabezudo et al., 2021).

Discussion

The FBBW reveals critical insights into the comparative advantages of EAE versus FAE technologies:

enzymatic-assisted extraction (EAE) offers superior specificity and efficiency, allowing tailored approaches to specific by-products through careful enzyme selection. However, its implementation depends heavily on commercial enzyme availability, increasing operational costs;
fermentation-assisted extraction (FAE), conversely, presents a more economically viable strategy, leveraging microorganism enzymatic activity during growth, though requiring longer processing times and adequate readily available carbon sources.

The research highlights that most agro-industrial by-products present strong cell walls limiting enzyme and microorganism accessibility. This challenge necessitates pretreatment strategies such as mild heat treatment or mechanical processing. The study emphasises that FAE applications typically require days for effective substrate metabolisation, whilst EAE achieves results within hours, albeit at higher cost.

A significant finding concerns the composition-dependent nature of upcycling strategies. Starch-rich by-products like potato peels prove ideal for enzyme production and biogas generation, whilst lignocellulosic materials such as shells and hulls present greater challenges but offer valuable phenolic compounds. The research demonstrates that understanding by-product composition is crucial for selecting appropriate biotechnological approaches.

The study addresses scalability concerns, noting that most existing literature focuses on laboratory-scale processes without considering industrial implementation. This limitation highlights the need for future research to prioritise scale-up studies and life cycle assessments to ensure laboratory findings translate effectively into practical applications.

Conclusions

The food by-products bioprocess wheel (FBBW) represents a significant advancement in facilitating sustainable upcycling strategies for the food industry. By providing clear visual guidance on biotechnological options for various by-products, the FBBW bridges the gap between academic research and industrial application. The tool’s comprehensive coverage of fruits, vegetables, crops, and cereals makes it valuable for identifying promising valorisation pathways.

The research conclusively demonstrates that both EAE and FAE technologies offer viable routes for converting food by-products into functional ingredients, though their application remains in early stages. The choice between technologies depends on specific by-product characteristics, target compounds, and economic considerations. EAE provides precision and efficiency at higher cost, whilst FAE offers economical processing with longer timeframes.

Future developments should focus on whole by-product upcycling rather than extract production alone, addressing the ultimate goal of minimising environmental footprint. The FBBW tool’s potential extends beyond current applications, suggesting possibilities for pilot-plant scale-up and facilitating technology transfer from research laboratories to industrial settings. This innovative approach aligns with global sustainability goals whilst offering practical solutions for the food industry’s waste challenges.

#Wasteless

Dario Dongo

References

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