The Monthly Digest – Food Waste – February & March 2018

Food Waste and by-products

R & D abstracts – February & March 2018

Deep eutectic solvents pretreatment of agro-industrial food waste (research)

Waste biomass from agro-food industries are a reliable and readily exploitable resource. From the circular economy point of view, direct residues from these industries exploited for production of fuel/chemicals is a winning issue, because it reduces the environmental/cost impact and improves the eco-sustainability of productions. The present paper reports recent results of deep eutectic solvent (DES) pretreatment on a selected group of the agro-industrial food wastes (AFWs) produced in Europe. In particular, apple residues, potato peels, coffee silverskin, and brewer’s spent grains were pretreated with two DESs, (choline chloride–glycerol and choline chloride–ethylene glycol) for fermentable sugar production. Pretreated biomass was enzymatic digested by commercial enzymes to produce fermentable sugars. Operating conditions of the DES pretreatment were changed in wide intervals. The solid to solvent ratio ranged between 1:8 and 1:32, and the temperature between 60 and 150 °C. The DES reaction time was set at 3 h. Optimal operating conditions were: 3 h pretreatment with choline chloride–glycerol at 1:16 biomass to solvent ratio and 115 °C. Moreover, to assess the expected European amount of fermentable sugars from the investigated AFWs, a market analysis was carried out. The overall sugar production was about 217 kt yr−1, whose main fraction was from the hydrolysis of BSGs pretreated with choline chloride–glycerol DES at the optimal conditions. The reported results boost deep investigation on lignocellulosic biomass using DES. This investigated new class of solvents is easy to prepare, biodegradable and cheaper than ionic liquid. Moreover, they reported good results in terms of sugars’ release at mild operating conditions (time, temperature and pressure).

Procentese A et al (2018) Biotechnology for Biofuels 11:37

Engineering yeast for utilization of alternative feedstocks (research)

Realizing the economic benefits of alternative substrates for commodity chemical bioproduction typically requires significant metabolic engineering of common model organisms, such as Saccharomyces cerevisiae. A growing toolkit is enabling engineering of non-conventional yeast that have robust native metabolism for xylose, acetate, aromatics, and waste lipids. Scheffersomyces stipitis was engineered to produce itaconic acid from xylose. Yarrowia lipolytica produced lipids from dilute acetate at over 100 g/L. Cutaneotrichosporon oleaginosus was engineered to produce omega-3 fatty acids and recently was shown to accumulate nearly 70% lipids when grown on aromatics as a carbon source. Further improvement to toolkits for genetic engineering of non-conventional yeast will enable future development of alternative substrate conversion to biochemicals.

Yaguchi A et al (2018) Current Opinion in Biotechnology 53:122-129

Conversion of lignocellulosic agave residues into liquid biofuels using an AFEX™-based biorefinery (research)

Agave-based alcoholic beverage companies generate thousands of tons of solid residues per year in Mexico. These agave residues might be used for biofuel production due to their abundance and favorable sustainability characteristics. In this work, agave leaf and bagasse residues from species Agave tequilana and Agave salmiana were subjected to pretreatment using the ammonia fiber expansion (AFEX) process. The pretreatment conditions were optimized using a response surface design methodology. We also identified commercial enzyme mixtures that maximize sugar yields for AFEX-pretreated agave bagasse and leaf matter, at ~ 6% glucan (w/w) loading enzymatic hydrolysis. Finally, the pretreated agave hydrolysates (at a total solids loading of ~ 20%) were used for ethanol fermentation using the glucose- and xylose-consuming strain Saccharomyces cerevisiae 424A (LNH-ST), to determine ethanol yields at industrially relevant conditions. Low-severity AFEX pretreatment conditions are required (100–120 °C) to enable efficient enzymatic deconstruction of the agave cell wall. These studies showed that AFEX-pretreated A. tequilana bagasse, A. tequilana leaf fiber, and A. salmiana bagasse gave ~ 85% sugar conversion during enzyme hydrolysis and over 90% metabolic yields of ethanol during fermentation without any washing step or nutrient supplementation. On the other hand, although lignocellulosic A. salmiana leaf gave high sugar conversions, the hydrolysate could not be fermented at high solids loadings, apparently due to the presence of natural inhibitory compounds. These results show that AFEX-pretreated agave residues can be effectively hydrolyzed at high solids loading using an optimized commercial enzyme cocktail (at 25 mg protein/g glucan) producing > 85% sugar conversions and over 40 g/L bioethanol titers. These results show that AFEX technology has considerable potential to convert lignocellulosic agave residues to bio-based fuels and chemicals in a biorefinery.

Flores-Gomez CA et al (2018) Biotechnology for Biofuels 11 :7

Biovalorization of brewers’ spent grain for the production of laccase and polyphenols (research)

Brewers’ spent grain (BSG) is the main solid by-product of the brewing process and is typically disposed of as cattle feed. In this study, BSG was evaluated as a substrate for the production of polyphenols and the lignin-degrading enzyme laccase using fungal solid-state fermentation by Trametes versicolor. Laccases are finding increasing applications in the food industry and polyphenols have benefits for human health. After 14 days of fermentation with T. versicolor, there was a 3.4-fold increase in the extraction of total polyphenols compared with untreated BSG. Using BSG as the sole source of carbon and nitrogen, maximum laccase activity was achieved after seven days of treatment with an activity of 560 U/L. Based on these results, BSG is suggested to be a good lignocellulose waste material to produce value-added products such as the enzyme laccase and polyphenols.

Tisma M et al (2018) Journal of the Institute of Brewing (in press)

Valorisation of food and beverage waste via saccharification for sugars recovery (research)

Valorisation of mixed food and beverage (F&B) waste was studied for the recovery of sugars via saccharification. Glucoamylase and sucrase were employed to hydrolyse the starch and sucrose present in the mixed F&B waste because of the high cost-effectiveness for such recovery. The Michaelis-Menten kinetics model suggests that preservatives and additives in beverages did not inhibit glucoamylase and sucrase during saccharification. High levels of glucose (228.1 g L−1) and fructose (55.7 g L−1) were efficiently produced within 12 h at a solid-to-liquid ratio of 37.5% (w/v) in 2.5 L bioreactors. An overall conversion yield of 0.17 g sugars per g of mixed F&B waste was obtained in mass balance analysis. Lastly, possible industrial applications of the sugar-rich hydrolysate and by-products are discussed. This study is believed to cast insights into F&B waste recycling via biotechnology to produce high-value added products to promote the establishment of a circular bio-economy.

Kwan TH et al (2018) Bioresource Technology 255:67-75

Electric energy production from food waste: Microbial fuel cells versus anaerobic digestion (research)

A food waste resourceful process was developed by integrating the ultra-fast hydrolysis and microbial fuel cells (MFCs) for energy and resource recovery. Food waste was first ultra-fast hydrolyzed by fungal mash rich in hydrolytic enzymes in-situ produced from food waste. After which, the separated solids were readily converted to biofertilizer, while the liquid was fed to MFCs for direct electricity generation with a conversion efficiency of 0.245 kWh/kg food waste. It was estimated that about 192.5 million kWh of electricity could be produced from the food waste annually generated in Singapore, together with 74,390 tonnes of dry biofertilizer. Compared to anaerobic digestion, the proposed approach was more environmentally friendly and economically viable in terms of both electricity conversion and process cost. It is expected that this study may lead to the paradigm shift in food waste management towards ultra-fast concurrent recovery of resource and electricity with zero-solid discharge.

Xin XD et al (2018) Bioresource Technology 255:281-287

The Monthly Digest – Food Waste – April & May 2018

Food Waste and by-products

R & D abstracts – April & May 2018

Food waste as a source of value‐added chemicals and materials: a biorefinery perspective (review)

As the availability of fossil‐based resources declines, there is an impending necessity of finding alternative feedstock able to secure the production of fuels and chemicals. Exploitation of biomass as renewable source of chemicals is an attractive possibility, in particular the one derived from food waste (FW). Every year, large amounts of waste are generated within or at the end of the food supply chain at the consumers use stage and hence its valorisation attracts great attention. FW has proven a valuable feedstock for its exploitation to produce a wide array of intermediates and products with promising applications in industry, owing to their similar performance with respect to established products. These include organic acids and furans (generally used as platform chemicals to further products); polymers like bacterial cellulose, polyhydroxyalkanoates or chitin; biosurfactants; biolubricants; or nanoparticles. This overview covers the latest trends in chemical, enzymatic and biotechnological processes reported in literature on the production of these chemicals and materials, with a focus on the use of FW as raw material.

Esteban J and Ladero M (2018) International Journal of Food Science and Technology 53:1095-1108

Techno-economic and profitability analysis of food waste biorefineries at European level (review)

Food waste represents a potential source to produce value-added materials replacing the use of virgin ones. However, the use of food waste as feedstock in biorefineries is still at an early stage of development and studies assessing its economic viability at large scale are lacking in the literature. This paper presents a techno-economic and profitability analysis of four food waste biorefineries that use wastes from tomato, potato, orange, and olive processing as feedstock. The study includes the assessment of potentially available quantities of those waste flows in Europe. Due to the low technology readiness level of this kind of biorefineries, a screening methodology to estimate the investment and manufacturing costs as well as two profitability ratios (the return on investment and the payback time) was adopted. Results show that not all the waste feedstocks have the same potential. The most profitable options are those related to implementing fewer plants, namely concentrating the production and capitalising on economies of scale while being at risk of increasing externalities, e.g. due to logistics of the feedstocks.

Cristobal J et al (2018) Bioresource Technology 259:244-252

Valorisation of fruit and vegetable waste from open markets for the production of 2,3-butanediol (research)

The bacterial strain Enterobacter ludwigii FMCC 204 was selected as the most efficient 2,3-butanediol (BDO) producer among five strains when cultivated on glucosefructosemannosearabinosexylosegalactose and sucrose in shake flask cultures. Plums, apples and pears were used for the production of fermentation medium via sequential maceration, suspension in water and centrifugation to collect the supernatant. Sugar production from mixed vegetables was evaluated via sulphuric acid treatment leading to 65.8% (w/w) of hemicellulose hydrolysis yield at initial solid concentrations of 50 g/L (on a dry basis) treated with 3% (v/v) H2SO4. Fed-batch cultures of E. ludwidgii on fruit derived feedstock resulted in BDO concentration, yield and productivity of 50 g/L, 0.4 g/g and 0.41 g/L/h. BDO production from vegetable waste hydrolysates via fed-batch cultures led to BDO concentration of 17.6 g/L. This study demonstrated that fruit and vegetable wastes from open markets can be used as fermentation feedstocks for BDO production.

Liakou V et al (2018) Food and Bioproducts Processing 108:27-36

Experimental and feasibility assessment of biogas production by anaerobic digestion of fruit and vegetable waste from Joburg Market (research)

Substrate-induced instability of anaerobic digestion from fruit and vegetable waste (FVW) results in low biogas yield. In this study, substrate management through fruit to vegetable mix ratio in a two-stage semi-continuous digester was investigated as a pathway for optimality of yield. The experiment conducted over 105 days with 62.52 kg of FVWs sourced from Joburg Market, South Africa showed that a stable process was achieved at a fruit to vegetable waste mix ratio of 2.2:2.8. At this ratio, optimal organic loading rate ranged between 2.68 and 2.97 kg VS/m3-d which resulted in a specific biogas yield of 0.87 Nm3/kg VS with 57.58% methane on average. The results of the experimental study were used as a feasibility assessment for a full-scale 45 tonnes/d plant for Joburg Market considering three energy pathways. The plant will produce 1,605,455 Nm3/y of biogas with the potential for offsetting 15.2% of the Joburg Market energy demand. Conversion of all biogas to biomethane was the most economically attractive energy pathway with a net present value of $2,428,021, an internal rate of return of 16.90% and a simple payback period of 6.17 years. This route avoided the greenhouse gas emission of 12,393 tonnes CO2, eq. The study shows that the anaerobic digestion of FVWs as sole substrate is possible with financial and environmental attractiveness.

Masebinu SO et al (2018) Waste management 75:236-250

Process design and techno-economic analysis of an integrated mango processing waste biorefinery (research)

This study evaluated costs and profitability associated with mango processing waste biorefinery plant with the goal of generating wealth from waste. Three pathways were evaluated (i) Only Pectin recovery (PEP) (ii) Pectin and Seed Oil recovery (PSEP), and (iii) whole biorefinery with multiple products (WMB). A plant capacity of 10 tons/h was considered as a base case for analysis. Effect of biomass feed composition on product yields were also reported in this study. The PSEP was found to be the best alternative for mango waste utilization. The NPV, IRR and PEP were $41 million, 34% and 2.4 years, respectively. In case of PEP and WMB, NPVs were $14.2 and $43.2 million; IRRs were 20% and 26%, and PBP were 4.2 and 3.4 years, respectively. Sensitivity analysis showed that plant capacity, plant operating days, and raw material composition were most important factors that influenced plant economics. Selling price of main product i.e. pectin had a major influence on plant economics. The effect of raw material price fluctuation however, did not influence plant economics significantly.

Arora A et al (2018) Industrial Crops and Products 116:24-34

Anaerobic digestion of orange peel in a semi-continuous pilot plant: An environmentally sound way of citrus waste management in agro-ecosystems (research)

The management of residues of citrus processing involves economic and environmental problems. In particular, the uncontrolled disposal of citrus processing waste near production sites can have heavy impacts on air, soil, surface water bodies and groundwater. Anaerobic digestion has been proposed as a viable alternative for citrus waste valorisation, if some problems, linked to the biochemical processes, are overcome. Although many experimental tests have studied the inhibitory effects of the high essential oil content of orange peel on biomethanisation processes, fewer experiences have been carried out in continuous or semi-continuous pilot digesters, more similar to the full-scale biogas plants, using real orange peel. This study has evaluated the methane production through anaerobic digestion of industrial orange peel using a pilot plant (84 L) with semi-continuous feeding at increasing Organic Loading Rates (OLR) and essential oil (EO) supply rates (EOsr) until the complete process inhibition. Under mesophilic conditions, the highest daily specific methane yield was achieved at OLR of 1.0 gTVS L−1 d−1 and EOsr of 47.6 mg L−1 d−1. Partial inhibition of the anaerobic digestion was detected at OLR and EOsr of 1.98 gTVS L−1 d−1 and 88.1 mg L−1 d−1, respectively and the process irreversibly stopped when OLR and EOsr reached 2.5 gTVS L−1 d−1 and 111.2 mg L−1 d−1, respectively. Under thermophilic conditions, the cumulative methane production (0.12 L gTVS−1) was about 25% of that under mesophilic conditions (0.46 L gTVS−1). The thermophilic digestion was completely inhibited at lower OLR (1.98 gTVS L−1 d−1) and EOsr (88.1 mg L−1 d−1) compared to mesophilic conditions. This study confirmed the suitability of anaerobic digestion of orange peel for biomethane production (provided that the right management of the process is set), in view of an environmentally sound way of agricultural residues management in agro-ecosystems.

Zema DA et al (2018) Science of the Total Environment 630:401-408

The Monthly Digest – Food Waste October 2017

Food wastes and by-products
R & D abstracts – October 2017


Putting together the puzzle of consumer food waste: Towards an integral perspective (review)

Although consumer food waste has increasingly received attention in both the public and the scientific domain, its complex nature is far from unraveled. This study aimed to contribute to an integral understanding of possible causal pathways of consumer food waste, by means of a configurative systematic literature review of potential factors of consumer food waste. Insights from 59 scientific articles have been systematically analysed and synthesised. Consumer food waste research is characterised by fragmentation, lack of differentiation, and a relative scarcity of explanatory research into causal mechanisms. Potential factors of consumer food waste have been identified and categorised into behavioural, personal, product and societal factors and subclusters of these categories. On the basis of a synthesised overview of 116 factors, a framework has been developed that conceptualises the generation of consumer food waste in relation to stages of the household food chain. This review sheds light on the context-dependent ways in which proposed factors may be related to food waste and the possibility of parallel causal routes. Food waste factors might exert their influence in unexpected, indirect or multiple ways, possibly explaining contradictory findings. They might interact with other factors or form a condition for other factors to play a role, or might be correlated with food waste without playing a causal role. The framework may facilitate an integral and context-sensitive systems perspective, thereby promoting studies that account for the complexity of consumer food waste and intervention programmes that are better targeted.

Roodhuyzen DMA et al (2017) Trends in Food Science & Technology 68:37-50


Bioplastics of native starches reinforced with passion fruit peel (research)

Industrial passion fruit juice production generates a large amount of passion fruit waste, which contains about 60% of fibers when dried and could be used as reinforcement of thermoplastic starch. This study aimed to develop an extruded starchy bioplastic reinforced with passion fruit peel (Pfp) (0, 4, 10, 16, and 20%), glycerol (60, 64, 70, 76, and 80 wt%), and starch mix (55% corn and 45% cassava) that were processed at varied screw speeds (66, 80, 100, 120, and 134 rpm). The response surface methodology was applied to analyze the effects of Pfp, glycerol, and screw speed. Mechanical properties, contact angle, and water permeability and solubility were the response variables. Addition of Pfp, up to 4%, improved the bioplastic mechanical properties. High addition of Pfp (16 and 20%) combined with the lowest screw speed (66 rpm) reduced bioplastic water solubility. Water vapor permeability slightly increased with the combination of increasing glycerol content and screw speed. Contact angle was not statically affected by the independent variables. The extrusion showed as an interesting tool that provided greater homogeneity of Pfp incorporated in starch bioplastic, though the mix would benefit from finer Pfp particle size distribution.

Moro TMA et al (2017) Food and Bioprocess Technology 10:1798-1808

Pilot scale fermentation coupled with anaerobic digestion of food waste – Effect of dynamic digestate recirculation (research)

The anaerobic digestion in double stage is a known and adopted system, but the process productivity and optimization still remain an aspect to investigate. The accumulation of organic acids (produced during fermentative metabolism) in the first stage generally decrease the pH below the optimal values (5.5). A pre-evaluation strategy by control charts for further pH control is proposed. The process combines in series the 1st Fermentation process and the 2nd Anaerobic Digestion process, using the recirculation of the anaerobic digestion effluent, rich in buffer agents, to control the pH in the 1st stage. The recycle ratio becomes a further operating parameter that should be properly managed. A proper management as dynamic recirculation flow allows to maintain the pH of the first phase to values higher than 5. Specific hydrogen production, specific methane production and volatile fatty acid production; 170 L/kgTVS at 40% H2, 750 L at 67% CH4 and 14 gCOD/L VFA were obtained respectively.

Gottardo M et al (2017) Renewable Energy 114 B:455-463

Effects of organic composition on the anaerobic biodegradability of food waste (research)

This work investigated the influence of carbohydrates, proteins and lipids on the anaerobic digestion of food waste (FW) and the relationship between the parameters characterising digestion. Increasing the concentrations of proteins and lipids, and decreasing carbohydrate content in FW, led to high buffering capacity, reduction of proteins (52.7–65.0%) and lipids (57.4–88.2%), and methane production (385–627 mLCH4/g volatile solid), while achieving a short retention time. There were no significant correlations between the reduction of organics, hydrolysis rate constant (0.25–0.66 d−1) and composition of organics. Principal Component Analysis revealed that lipid, C, and N contents as well as the C/N ratio were the principal components for digestion. In addition, methane yield, the final concentrations of total ammonia nitrogen and free ammonia nitrogen, final pH values, and the reduction of proteins and lipids could be predicted by a second-order polynomial model, in terms of the protein and lipid weight fraction.

Li Y et al (2017) Bioresource Technology 243:836-845

Effects of organic composition on mesophilic anaerobic digestion of food waste (research)

Anaerobic digestion of food waste (FW) has been widely investigated, however, little is known about the influence of organic composition on the FW digestion process. This study aims to identify the optimum composition ratios of carbohydrate (CA), protein (CP) and lipid (EE) for maintaining high methane yield and process stability. The results show that the CA–CP–EE ratio was significantly correlated with performance and degradability parameters. Controlling the CA–CP–EE ratio higher than 1.89 (CA higher than 8.3%, CP lower than 5.0%, and EE lower than 5.6%) could be an effective way to maintain stable digestion and achieve higher methane production (385–627 mL/g VS) and shorter digestion retention (196–409 h). The CA-CP-EE ratio could be used as an important indicator for digestion performance. To effectively evaluate organic reduction, the concentration and removal efficiency of organic compositions in both solid phases and total FW should be considered.

Li Y et al (2017) Bioresource Technology 244:213-224

The Monthly Digest – Food Waste September 2017

Food wastes and by-products
R & D abstracts – September 2017
Enhanced polyhydroxyalkanoate (PHA) production from the organic fraction of municipal solid waste by using mixed microbial culture (research)

In Europe, almost 87.6 million tonnes of food waste are produced. Despite the high biological value of food waste, traditional management solutions do not consider it as a precious resource. Many studies have reported the use of food waste for the production of high added value molecules. Polyhydroxyalkanoates (PHAs) represent a class of interesting bio-polyesters accumulated by different bacterial cells, and has been proposed for production from the organic fraction of municipal solid waste (OFMSW). Nevertheless, until now, no attention has been paid to the entire biological process leading to the transformation of food waste to organic acids (OA) and then to PHA, getting high PHA yield per food waste unit. In particular, the acid-generating process needs to be optimized, maximizing OA production from OFMSW. To do so, a pilot-scale Anaerobic Percolation Biocell Reactor (100 L in volume) was used to produce an OA-rich percolate from OFMSW which was used subsequently to produce PHA. The optimized acidogenic process resulted in an OA production of 151 g kg−1 from fresh OFMSW. The subsequent optimization of PHA production from OA gave a PHA production, on average, of 223 ± 28 g kg−1total OA fed. Total mass balance indicated, for the best case studied, a PHA production per OFMSW weight unit of 33.22 ± 4.2 g kg−1 from fresh OFMSW, corresponding to 114.4 ± 14.5 g kg−1 of total solids from OFMSW. PHA composition revealed a hydroxybutyrate /hydroxyvalerate (%) ratio of 53/47 and Mw of 8∙105 kDa with a low polydispersity index, i.e. 1.4. This work showed how by optimizing acidic fermentation it could be possible to get a large amount of OA from OFMSW to be then transformed into PHA. This step is important as it greatly affects the total final PHA yield. Data obtained in this work can be useful as the starting point for considering the economic feasibility of PHA production from OFMSW by using mixed culture.

Colombo B et al (2017) Biotechnology for Biofuels 10:201


Treatment of supermarket vegetable wastes to be used as alternative substrates in bioprocesses (research)

Fruits and vegetables have the highest wastage rates at retail and consumer levels. These wastes have promising potential for being used as substrates in bioprocesses. However, an effective hydrolysis of carbohydrates that form these residues has to be developed before the biotransformation. In this work, vegetable wastes from supermarket (tomatoes, green peppers and potatoes) have been separately treated by acid, thermal and enzymatic hydrolysis processes in order to maximise the concentration of fermentable sugars in the final broth. For all substrates, thermal and enzymatic processes have shown to be the most effective. A new combined hydrolysis procedure including these both treatments was also assayed and the enzymatic step was successfully modelled. With this combined hydrolysis, the percentage of reducing sugars extracted was increased, in comparison with the amount extracted from non-hydrolysed samples, approximately by 30% in the case of tomato and green peeper wastes. For potato wastes this percentage increased from values lower than 1% to 77%. In addition, very low values of fermentation inhibitors were found in the final broth.

Diaz AI et al (2017) Waste Management 67:59-66

The Monthly Digest – Food waste – July & August 2017

Food wastes and by-products
R & D abstracts – July & August 2017
Microbial processing of fruit and vegetable wastes into potential biocommodities: a review

The review focuses on some of the high value-end biocommodities, such as fermented beverages, single-cell proteins, single-cell oils, biocolors, flavors, fragrances, polysaccharides, biopesticides, plant growth regulators, bioethanol, biogas and biohydrogen, developed from the microbial processing of fruit and vegetable wastes. Microbial detoxification of fruit and vegetable processing effluents is briefly described. The advances in genetic engineering of microorganisms for enhanced yield of the above-mentioned biocommodities are elucidated with selected examples. The bottleneck in commercialization, integrated approach for improved production, techno-economic feasibility and real-life uses of some of these biocommodities, as well as research gaps and future directions are discussed.

Panda SK et al (2017) Critical Reviews in Biotechnology (in press)


Waste biorefineries: Enabling circular economies in developing countries (review)

This paper aims to examine the potential of waste biorefineries in developing countries as a solution to current waste disposal problems and as facilities to produce fuels, power, heat, and value-added products. The waste in developing countries represents a significant source of biomass, recycled materials, chemicals, energy, and revenue if wisely managed and used as a potential feedstock in various biorefinery technologies such as fermentation, anaerobic digestion (AD), pyrolysis, incineration, and gasification. However, the selection or integration of biorefinery technologies in any developing country should be based on its waste characterization. Waste biorefineries if developed in developing countries could provide energy generation, land savings, new businesses and consequent job creation, savings of landfills costs, GHG emissions reduction, and savings of natural resources of land, soil, and groundwater. The challenges in route to successful implementation of biorefinery concept in the developing countries are also presented using life cycle assessment (LCA) studies.

Nizami AS et al (2017) Bioresource Technology 241:1101-1117


Valorization of potato peel: a biorefinery approach (review)

Potato is the fourth main crop consumed worldwide and is an important constituent in the human diet. Consequently, potato is widely used in food-processing industries. However, these industries generate massive amounts of potato peel (PP) as a by-product, which is usually considered a waste, and is discarded. Interestingly, recent research suggests that PP is a valuable source of bioactive compounds, which can be converted into value-added products. In this study, we review the physicochemical composition and valorization of PP. In addition to being used as a dietary fiber or medicine, the value-added products obtained by the fermentation of PP have multiple uses, including their use as adsorbents, biocomposites and packaging materials. These products can also be used in energy production, biopolymer film development, corrosion inhibition and the synthesis of cellulose nanocrystals. The biorefinery approach for PP will increase the value of this waste by producing an array of value-added products and reducing extensive waste generation.

Pathak PD et al (2017) Critical Reviews in Biotechnology (in press)


Optimization of cultivation conditions in banana wastes for production of extracellular β-glucosidase by Trichoderma harzianum Rifai efficient for in vitro inhibition of Macrophomina phaseolina (research)

The present study was carried out to optimize the physical and nutritional parameters for cultivation of Trichoderma harzianum Rifai for production of extracellular β-glucosidase, an alternative to chemcial fungicides to control Macrophomina phaseolina, which causes charcoal rot disease in crops. Response surface methodology by the Box–Behnken design (BBD) based on four factors (temperature, carbon sources, inoculum size and pH) was used for optimization of the cultivation conditions to produce β-glucosidase using agro-industrial banana wastes. The highest β-glucosidase activity (1483.27 U/mL) was attained under optimized cultivation conditions: ∼36 ºC and pH 7.3, using carbon source and inoculum size of 10% (w/v) and 5% (w/v), respectively. It is noteworthy that the low deviation values (0.09−0.44%) in the verification experiments (R1, R2 and R3) inferred the generated model was accurate to predict optimal cultivation conditions of T. harzianumRifai. Likewise, the obtained diameters of inhibition zones ranging from 58.00−38.66 mm following treatment with β-glucosidase was found comparable to other in vitro tests using pure T. harzianum isolates and chemical fungicides. Hence, the findings indicated that it was feasible to use β-glucosidase as a greener alternative to chemical fungicides for control of M. phaseolina infection and consequently, for protection of crops against charcoal rot disease.

Khalili E et al (2017) Biotechnology & Biotechnological Equipment (in press)


Agrowaste to vanillin conversion by a natural Pediococcus acidilactici strain BD16 (research)

Owing to its flavoring, antimicrobial, antioxidant and anticarcinogenic nature, vanillin is widely used in foods, beverages, perfumes and pharmaceutical products. Ferulic acid (FA) is an important precursor of vanillin which is abundant in cereals like maize, rice and wheat and sugar beet. A major drawback of microbial vanillin production from FA is the degradation and biotransformation of toxic vanillin to other phenolic derivatives. The present study is undertaken to explore microbial vanillin production from FA precursor rice bran by employing vanillin-resistant Pediococcus acidilactici BD16, a natural lactic acid bacteria isolate. Extracellular, intracellular and cellular vanillin dehydrogenase activity was found least, which was minimized vanillin degradation, and the strain resists more than 5 g L−1 vanillin in the medium. A metabolomics approach was followed for the detection of FA, vanillin and other metabolites generated during fermentation of rice bran medium. A metabolic pathway was also predicted for vanillin biosynthesis. Approximately 1.06 g L−1 of crude vanillin was recovered from rice-bran-containing medium and this further offers scope for the industrial utilization of the organism and its genetic manipulation to enhance production of biovanillin.

Chakraborty D et al (2017) Environmental Technology 38:1823-1834


Potato peels: A potential food waste for amylase production (research)

In the present study, thermophilic and amylase producing bacterium Bacillus subtilis K-18 (KX881940) was isolated from local environment and identified by 16S rRNA gene sequencing technology. The amylase producing potential was checked by starch hydrolysis test using potato peels as carbon source. Central composite design (CCD) of response surface methodology (RSM) was used to optimize multiple process parameters such as substrate concentration, inoculum size, yeast extract, and pH. The optimized conditions obtained from RSM model were substrate concentration (2%), inoculum size (4%), yeast extract concentration (0.6%), and pH (5) yielding amylase activity of 1394.145 IU/ml after 24 hr of fermentation period at 50 °C. The maximum saccharification by indigenously produced amylase was 32.03% after 24 hr of incubation. The results confirmed that amylase produced by this newly isolated Bacillus subtilis K-18 (KX881940) could be potent strain for industrial process particular for biofuel production. The enzyme produced in this study could be effectively used in hydrolysis of starch to produce sugars which could be widely used for the production of various chemicals such ethanol and other products through fermentation. This enzyme also has potential application in textile industry.

Mushtaq Q et al (2017) Journal of Food Process Engineering 40 (in press)


Minimally processed beetroot waste as an alternative source to obtain functional ingredients (research)

Large amounts of waste are generated by the minimally processed vegetables industry, such as those from beetroot processing. The aim of this study was to determine the best method to obtain flour from minimally processed beetroot waste dried at different temperatures, besides producing a colorant from such waste and assessing its stability along 45 days. Beetroot waste dried at 70 °C originates flour with significant antioxidant activity and higher betalain content than flour produced from waste dried at 60 and 80 °C, while chlorination had no impact on the process since microbiological results were consistent for its application. The colorant obtained from beetroot waste showed color stability for 20 days and potential antioxidant activity over the analysis period, thus it can be used as a functional additive to improve nutritional characteristics and appearance of food products. These results are promising since minimally processed beetroot waste can be used as an alternative source of natural and functional ingredients with high antioxidant activity and betalain content.

Porto Dalla Costa A et al (2017) Journal of Food Science and Technology 54:2050-2058


Comparison of the anaerobic digestion at the mesophilic and thermophilic temperature regime of organic wastes from the agribusiness (research)

An overall kinetic power law model has been successfully applied to study the anaerobic digestion of agricultural wastes. In this comparative kinetic study feed composition, organic load rate, residence time and process temperature have been systematically varied in an automated semi-continuous fermentation system to obtain the dependency of the rate of degradation as biogas production on the organic load rate and temperature. The results show that the overall reaction order depend only on the Chemical Oxygen Demand (COD) at values between 3.6 and 3.7. The Arrhenius approach shows a shift in the rate determining step between the mesophilic and thermophilic temperature regimes. The activation energy at the temperature insensitive mesophilic regime is very small at 8.9 (kJ/mole), while the activation energy at the temperature sensitive thermophilic regime lies around 117 (kJ/mole).

Almeida Streitwieser D (2017) Bioresource Technology 241:985-982

The Monthly Digest – Food waste – May 2017

Food wastes and by-products
R & D abstracts – May 2017
Biofuels from food processing wastes (review)

Food processing industry generates substantial high organic wastes along with high energy uses. The recovery of food processing wastes as renewable energy sources represents a sustainable option for the substitution of fossil energy, contributing to the transition of food sector towards a low-carbon economy. This article reviews the latest research progress on biofuel production using food processing wastes. While extensive work on laboratory and pilot-scale biosystems for energy production has been reported, this work presents a review of advances in metabolic pathways, key technical issues and bioengineering outcomes in biofuel production from food processing wastes. Research challenges and further prospects associated with the knowledge advances and technology development of biofuel production are discussed.

Zhang Z et al (2016) Current Opinion in Biotechnology 38:97-105


Bioelectrochemical conversion of waste to energy using microbial fuel cell technology (review)

Numerous traditional methods are available for the conversion of waste to energy (WTE) such as incineration, anaerobic digestion, pyrolysis, gasification. Most of them suffer from low efficiency and high energy requirements. Microbial fuel cell (MFC) technology is an excellent alternative for the generation of renewable and sustainable energy and has the potential to help alleviate the current global energy crisis. The total wastewater generated in India is almost 250% of the total treatment capacity, and the Government is, therefore, looking for a sustainable solution for the treatment of waste. Indian population consumes around 700 billion cubic meters of water annually, and this figure will rise to 950 and 1422 billion m3 by 2025 and 2050 respectively. Although treatment of wastewater is a serious concern, the energy recovery potential of wastewater has not yet been fully developed. A survey has been conducted through this study, and it was estimated that MFC technology has the potential to generate around 23.3 and 40 Tera Watt (TW) power by 2025 and 2050 by treating wastewater generated throughout India (urban areas) if utilized properly. This review article presents a various aspect of MFC technology for a proper understanding by the readers. This will be a unique study wherein the energy recovery potential of the wastewater produced in the Indian subcontinent has been estimated through MFC technology. A number of factors affecting the performance of MFC such as electron losses, reactor configuration, and varying concentration must be taken into account to augment output energy. The article summarizes an extensive literature survey of some selected papers published in the last decade.

Khan MD et al (2017) Process Biochemistry (in press)


Fruit and vegetable waste management and the challenge of fresh-cut salad (review)

The fruit and vegetable sector generates large amounts of waste. In industrialized countries, fruit and vegetable waste (FVW) is mainly generated before reaching consumers, due to programmed overproduction and unfulfillment of retailer quality standards. FVW poses environmental problems due to its high biodegradability, represents a loss of valuable biomass and an economic cost for companies. Different reduction, reuse and recycle strategies to tackle FVW have been proposed.
This review paper summarizes these strategies, underlying their main advantages and pitfalls. In particular, fresh-cut salad waste was considered as a particularly challenging FVW, due to its low concentration of nutrients (e.g. polyphenols, pigments, fiber). Different management strategies can be successfully applied to FVW. Among them, the extraction of specific functional compounds was found to be one of the most studied in the last years. This suggests that FVW can be considered a source of valuable ingredients and products. To maximally exploit these FVW potentialities, a rational strategy is required. The latter should be developed using a step-procedure including waste characterization, output definition, process design and feasibility study. The application of this procedure to the case of fresh-cut salad waste was presented. Based on the review of currently applied and potential salad waste management strategies, an operational scheme for the development of alternative strategies was proposed. This scheme considers the exploitation of traditional and novel technologies, even applied in combination, for salad waste valorization.

Plazzotta S et al (2017) Trends in Food Science & Technology 63:51-59


An overview: Recycling of solid barley waste generated as a by-product in distillery and brewery (review)

This overview has focused on the options available for the utilisation of residual-biomass generated in distillery and brewery for the production of added-value products. Bio-processing approaches have been reviewed and discussed for the economical bioconversion and utilisation of this waste for the production of bioproducts, such as lactic acid, enzymes, xylitol and animal feed. Though this overview provides several options for the bioprocessing of this residual material, a more suitable one could be chosen according to the processing-facilities available and the amount of residue available in local area. The feasibility of any chosen process should be evaluated on the basis of cost of material available, its local utilisation for animal feed, and the overall economical advantages that could be gained by changing its current traditional landfill use to produce higher added value products.

Singh Nigam P (2017) Waste Management 62:255-261


Exploitation of grape marc as functional substrate for lactic acid bacteria and bifidobacteria growth and enhanced antioxidant activity (research)

This study aimed at using grape marc for the growth of lactic acid bacteria and bifidobacteria with the perspective of producing a functional ingredient having antioxidant activity. Lactobacillus plantarum 12A and PU1, Lactobacillus paracasei 14A, and Bifidobacterium breve 15A showed the ability to grow on grape marc (GM) based media. The highest bacterial cell density (>9.0 CFU/g) was found in GM added of 1% of glucose (GMG). Compared to un-inoculated and incubated control fermented GMG showed a decrease of carbohydrates and citric acid together with an increase of lactic acid. The content of several free amino acids and phenol compounds differed between samples. Based on the survival under simulated gastro-intestinal conditions, GMG was a suitable carrier of lactic acid bacteria and bifidobacteria strains. Compared to the control, cell-free supernatant (CFS) of fermented GMG exhibited a marked antioxidant activity in vitro. The increased antioxidant activity was confirmed using Caco-2 cell line after inducing oxidative stress, and determining cell viability and radical scavenging activity through MTT and DCFH-DA assays, respectively. Supporting these founding, the SOD-2 gene expression of Caco-2 cells also showed a lowest pro-oxidant effect induced by the four CFS of GMG fermented by lactic acid bacteria and bifidobacteria. This study aimed at using grape marc for the growth of lactic acid bacteria and bifidobacteria with the perspective of producing a functional ingredient having antioxidant activity. Lactobacillus plantarum 12A and PU1, Lactobacillus paracasei 14A, and Bifidobacterium breve 15A showed the ability to grow on grape marc (GM) based media. The highest bacterial cell density (>9.0 CFU/g) was found in GM added of 1% of glucose (GMG). Compared to un-inoculated and incubated control fermented GMG showed a decrease of carbohydrates and citric acid together with an increase of lactic acid. The content of several free amino acids and phenol compounds differed between samples. Based on the survival under simulated gastro-intestinal conditions, GMG was a suitable carrier of lactic acid bacteria and bifidobacteria strains. Compared to the control, cell-free supernatant (CFS) of fermented GMG exhibited a marked antioxidant activity in vitro. The increased antioxidant activity was confirmed using Caco-2 cell line after inducing oxidative stress, and determining cell viability and radical scavenging activity through MTT and DCFH-DA assays, respectively. Supporting these founding, the SOD-2 gene expression of Caco-2 cells also showed a lowest pro-oxidant effect induced by the four CFS of GMG fermented by lactic acid bacteria and bifidobacteria.

Campanella D et al (2017) Food Microbiology 65:25-35


Pie waste – A component of food waste and a renewable substrate for producing ethanol (research)

Sugar-rich food waste is a sustainable feedstock that can be converted into ethanol without an expensive thermochemical pretreatment that is commonly used in first and second generation processes. In this manuscript we have outlined the pie waste conversion to ethanol through a two-step process, namely, enzyme hydrolysis using commercial enzyme products mixtures and microbial fermentation using yeast. Optimized enzyme cocktail was found to be 45% alpha amylase, 45% gamma amylase, and 10% pectinase at 2.5 mg enzyme protein/g glucan produced a hydrolysate with high glucose concentration. All three solid loadings (20%, 30%, and 40%) produced sugar-rich hydrolysates and ethanol with little to no enzyme or yeast inhibition. Enzymatic hydrolysis and fermentation process mass balance was carried out using pie waste on a 1000 g dry weight basis that produced 329 g ethanol at 20% solids loading. This process clearly demonstrates how food waste could be efficiently converted to ethanol that could be used for making biodiesel by reacting with waste cooking oil.

Magyar M et al (2017) Waste Management 62:247-254

The Monthly Digest – Food waste – April 2017

Food wastes and by-products
R & D abstracts – April 2017
Wastes and by-products: Upcoming sources of carotenoids for biotechnological purposes and health-related applications

Bioresidues valorization has gained a pivotal relevance in the last years, directly moved by consumers’ demands for heathier and safer products (food, cosmetics, supplements, drugs, and so on) and by industrial companies that need to adapt their manufacturing procedures to increasingly strict regulatory guidelines. Most of the natural ingredients are considered more sought and safer than synthetic ones, but also more expensive and less abundant. Therefore, the recovery of valuable active ingredients from wastes and by-products may be an interesting and upcoming strategy. The present report aims to provide an extensive approach to bioresidues valorization, focusing its chemical composition in terms of carotenoids content and their upcoming uses for biotechnological purposes. Daily produced and discharged industrial bioresidues derived from vegetable (peel, seeds, pericarp) and animal (wastewater, crustacean’s cephalothorax and carapace, scales, tails) sources comprise the richest sources of carotenoids (carotenes and xanthophylls). Different techniques are commonly used for carotenoids recovery being the extraction with organic solvents the most frequently used. Supercritical fluid extraction, microwave- and enzyme-assisted extractions are applied, but mainly in combination. This area opens fascinating opportunities to discover and to design novel strategies for carotenoids production/accumulation, foodstuffs valorization and provide valuable ingredients to different industrial sectors.

Martins N and Ferreira CFR (2017) Trends in Food Science and Technology 62:33-48

Bioenergy potential from food waste in California

Food waste makes up approximately 15% of municipal solid waste generated in the United States, and 95% of food waste is ultimately landfilled. Its bioavailable carbon and nutrient content makes it a major contributor to landfill methane emissions, but also presents an important opportunity for energy recovery. This paper presents the first detailed analysis of monthly food waste generation in California at a county level, and its potential contribution to the state’s energy production. Scenarios that rely on excess capacity at existing anaerobic digester (AD) and solid biomass combustion facilities, and alternatives that allow for new facility construction, are developed and modeled. Potential monthly electricity generation from the conversion of gross food waste using a combination of AD and combustion varies from 420 to 700 MW, averaging 530 MW. At least 66% of gross high moisture solids and 23% of gross low moisture solids can be treated using existing county infrastructure, and this fraction increases to 99% of high moisture solids and 55% of low moisture solids if waste can be shipped anywhere within the state. Biogas flaring practices at AD facilities can reduce potential energy production by 10 to 40%.

Breunig HM et al (2017) Environmental Science and Technology 51:1120-1128

Utilization of inulin-containing waste in industrial fermentations to produce biofuels and bio-based chemicals

Inulins are polysaccharides that belong to an important class of carbohydrates known as fructans and are used by many plants as a means of storing energy. Inulins contain 20 to several thousand fructose units joined by β-2,1 glycosidic bonds, typically with a terminal glucose unit. Plants with high concentrations of inulin include: agave, asparagus, coffee, chicory, dahlia, dandelion, garlic, globe artichoke, Jerusalem artichoke, jicama, onion, wild yam, and yacón. To utilize inulin as its carbon and energy source directly, a microorganism requires an extracellular inulinase to hydrolyze the glycosidic bonds to release fermentable monosaccharides. Inulinase is produced by many microorganisms, including species of Aspergillus, Kluyveromyces, Penicillium, and Pseudomonas. We review various inulinase-producing microorganisms and inulin feedstocks with potential for industrial application as well as biotechnological efforts underway to develop sustainable practices for the disposal of residues from processing inulin-containing crops. A multi-stage biorefinery concept is proposed to convert cellulosic and inulin-containing waste produced at crop processing operations to valuable biofuels and bioproducts using Kluyveromyces marxianus, Yarrowia lipolytica, Rhodotorula glutinis, and Saccharomyces cerevisiae as well as thermochemical treatments.

Hughes SR et al (2017) World Journal of Microbiology and Biotechnology 33:78

Effect of seasonal variations of organic loading rate and acid phase on methane yield of food waste leachate in South Korea

The objective of this study was to determine the effect of seasonal variations of organic loading rate (OLR) and acidogenic phase on methane yield of food waste leachate (FWL) treated in biogas facility in South Korea. A biogas facility operating in G city was selected as the target for this study. Remarkable seasonal fluctuations in methane yield occurred in this facility repeatedly. Methane yield in the summer was significantly lower compared to that in other seasons. In order to determine the operation efficiency, precision investigation (methane yield, OLR, etc) was conducted from March 2014 to April 2015. Characteristic parameters and operating factors of a two-stage anaerobic digestion were analyzed to obtain volatile fatty acids (VFAs), chemical oxygen demand, nutrients, total nitrogen, and so on. Data comparison revealed that the monthly average values of OLR and VFAs tended to increase rapidly in the summer (up to 3.92 kgVS/m3 day and 9263 mg/L, respectively). In contrast, methane yield in the same season was at 0.28 Sm3CH4/kg VS, which was much lower than the average value (0.42 Sm3CH4/kg VS) of methane yield in other seasons. The decrease in methane yield ranged from 69.0 to 57.9% in the summer. These results suggested that methane yield might be influenced by the operating conditions with seasonal organic loading fluctuations. In other words, methane yield might be affected by a shock load of VFAs due to inapposite operation of acidogenic phase with easily degradable FWL, particularly in the summer. The results of this study will provide important information on how an ongoing biogas facility of FWL should be operated in the summer.

Lee DJ et al (2017) Applied Biological Chemistry 60:87-93

Valorization of food waste – The 8 methods to be implemented

Before composting or performing anaerobic digestion of food waste, consider removing products that have commercial value.


Orange Peels

Limonene in orange waste makes composting or anaerobic digestion difficult to achieve. Limonene extraction is easy and fast. Limonene oil is sought after on the market for its olfactory and antibacterial value.





Coffee grounds

Coffee grounds can contain up to 20% of oil that can be extracted before composting or anaerobic digestion. Coffee oil can be sold on the market and replace palm oil.





Pectin of apples or oranges

Plant pectin can be removed from apple or orange peels and scraps and resold on the market for applications in food and pharma.





Chitin and Chitosan of Crustaceans

Chitin can be recovered by an easy process from crustacean residues such as crabs or shrimp. Chitin and its derivative the Chitosan are a product of high value as they are used in the engineering of cartilage tissues.





Whey Protein and Lactose

Whey is a residue of cheese production. Protein and lactose can be removed and marketed as food supplements.





Ferulic acid from rice husks

The residues from rice production contain a high concentration of ferulic acid. The latter has a high commercial value on the market and can be marketed for applications in pharma and cosmetics.






Wood residues or coconut fiber are rich in lignin. The process is well known and makes it possible to produce vanilla from lignin, which can be sold on the market.






Fibers and starch from banana peels

Banana peels are rich in fiber, starch and banana flavours. These constituents can be extracted from the banana peel and sold on the market.

Valorization of milk whey for aroma compounds production

The aim of this collaborative study between Eptes and universities in Greece, Germany, and Poland was to investigate the capacity of different yeast strains to grow on cow and goat acid whey, to assimilate different carbon sources and to produce aroma compounds. Twenty different yeasts (with GRAS status) were tested. Two kinds of acid whey, from cows and goats, were characterized in terms of their main chemical components (carbohydrates, organic acids, aminoacids, FAN, total nitrogen) using HPLC techniques and chemical methods. The most effective yeast strains were found to be those belonging to the genera Kluyveromyces, Wickerhamomyces and Saccharomyces. Three K. marxianus strains, one wine strain S. cerevisiae and one strain of W. anomalus were selected based on their ability to grow on whey agar, assimilation profiles and aroma profiles. Their ability to grow on mixed cow and goat acid whey under varying environmental conditions (pH level, supplementation, temperature, oxygen availability) was evaluated.

A selection of 80 samples were evaluated for their flavours profile compositions. The influence of pH, temperature, aeration and supplementation level on the volatile fraction of acid whey fermented with selected yeast strains, i.e. Saccharomyces cerevisiae, Wickerhamomyces anomalus and Kluyveromyces marxianus, was investigated in terms of aroma compounds production. Headspace solid-phase microextraction technique (HS-SPME) coupled to the gas chromatography–mass spectrometry (GC-MS) analysis was applied to characterize volatile compounds of the samples. More than 50 compounds were detected, which belonged to different chemical classes and could come either from different reaction pathways occurring during fermentation or from raw material. The most important compounds were found to be 3-methyl-1-butanol, ethyl alcohol, phenylethyl alcohol, ethyl acetate, ethyl octanoate, 2-phenylethyl acetate, acetic acid, butanoic acid, etc. that contribute to the aroma character of the samples with alcoholic, malty, cheesy, sour, sweet and rose-like notes. In general, the aroma profile of the samples depended on the yeast strain used, and was greatly affected by the temperature and aeration conditions applied during fermentation.

Valorization of wine lees for biodiesel production (french text)

La demande en acides gras pour la production notamment de biodiesel a augmenté d’environ 4% par an au cours des 10 dernières années. Avec cet accroissement constant, on assiste à une pression inquiétante concernant la production des huiles végétales dans les régions tropicales. Ceci en effet se traduit par la déforestation de certaines régions en Amérique latine et en Asie et la transformation des forêts en terres agricoles plus rentables pour la production de l’huile végétale. Aussi, l’utilisation de produits comestibles à des fins pour la production de biocarburant comme le biodiesel contribue à la hausse des prix des denrées alimentaires sur le marché mondial. Il est donc important de trouver d’autres sources pour la production de biocarburant.

Le biodiesel est obtenu aujourd’hui par transestérification des huiles végétales comme l’huile de colza ou l’huile de palme. La production mondiale en biodiesel a été d’environ 8.6 MT en 2007 (EU 63%).

Notons aussi que le biodiesel est également produit aujourd’hui par la transestérification des acides gras obtenus à partir des microalgues. Cependant, ce type de production n’est pas très répondu dans tous les pays et reste pour le moment à l’échelle industrielle concentré principalement en Chine, aux États-Unis, et en Allemagne.

La biomasse de la lie de vin constitue une source intéressante d’un point de vue économique pour l‘extraction des composés à valeur ajoutée comme les acides gras qui pourraient être transformés en biodiesel. Aujourd’hui, la lie de vin est filtrée d’abord puis compostée ou évacuée directement par épandage sur les sols.

Cette méthode de valorisation par compostage ou par épandage est certes pratique et intéressante pour les petits vignerons, mais ne l’est pas pour les grands producteurs. En effet, les coûts du transport, du compostage ou de l’épandage des grands volumes de ce déchet constituent les inconvénients majeurs. Aussi, il faut noter que l’épandage appauvrit la qualité des sols agricoles et il augmente dans beaucoup de fois leur degré d’acidité.

Le biodiesel est une énergie renouvelable qui peut être utilisée dans la plupart des moteurs diesel. Le biodiesel est biodégradable et renouvelable et d’un point de vue économique, il peut aider à réduire la dépendance au pétrole.

Les esters d’acides gras (biodiesels) sont mélangés (5% à 30%) en général avec du diesel de source fossile pour produire ce que l’on appelle couramment le biodiesel. La production de biodiesel en Suisse est insignifiante comparée à la production au sein de l’Union européenne. En Allemagne par exemple, le biodiesel est vendu déjà dans près de 2000 stations-service, alors qu’en Suisse, le biodiesel est peu répondu et il est obtenu principalement par transformation des huiles de friture usagées.

Le projet de la valorisation de la lie de vin en biodiesel financé par la Fondation Suisse pour le climat a été mis en place avec comme objectif le développement d’un procédé qui permettrait la transformation de la biomasse de la lie de vin en biodiesel. Cette valorisation se ferait in-situ afin de réduire également la quantité de CO2 chaque année émise durant le transport d’entre les sites des producteurs de ce déchet et les stations de compostages.