Food Processing Residues Research Articles

Biochar from Co-Pyrolyzed Municipal Sewage Sludge (MSS): Part 1: Evaluating Types of Co-Substrates and Co-Pyrolysis Conditions.

With the increasing production of municipal sewage sludge (MSS) worldwide, the development of efficient and sustainable strategies for its management is crucial. Pyrolysis of MSS offers several benefits, including volume reduction, pathogen elimination, and energy recovery through the production of biochar, syngas, and bio-oil. However, the process can be limited by the composition of the MSS, which can affect the quality of the biochar. Co-pyrolysis has emerged as a promising solution for the sustainable management of MSS, reducing the toxicity of biochar and improving its physical and chemical properties to expand its potential applications. This review discusses the status of MSS as a feedstock for biochar production. It describes the types and properties of various co-substrates grouped according to European biochar certification requirements, including those from forestry and wood processing, agriculture, food processing residues, recycling, anaerobic digestion, and other sources. In addition, the review addresses the optimization of co-pyrolysis conditions, including the type of furnace, mixing ratio of MSS and co-substrate, co-pyrolysis temperature, residence time, heating rate, type of inert gas, and flow rate. This overview shows the potential of different biomass types for the upgrading of MSS biochar and provides a basis for research into new co-substrates. This approach not only mitigates the environmental impact of MSS but also contributes to the wider goal of achieving a circular economy in MSS management.

Co-designing sustainable biochar business models with sub-Saharan African communities for inclusive socio-economic transformation

Smallholder farmers in sub-Saharan Africa (SSA) encounter multiple livelihood challenges. Embracing circular bioeconomy principles, particularly considering agricultural and food processing residues, could enable inclusive, locally led, sustainable development pathways within rural communities. Biochar products are one such example of a bio-based material that can be generated using circular principles and deployed for sustainable community development, including among smallholder farmers. This research leverages empirical evidence from four SSA regions to explore the potential of inclusive and sustainable biochar business models, namely: (i) Northern Region, Ghana, (ii) Yamoussoukro, Côte d’Ivoire, (iii) Casamance, Senegal, and (iv) Western Region, Uganda. Co-creation workshops using the Triple-Layered Business Model Canvas framework were carried out in each region with local stakeholders to evaluate the social, ecological, and economic implications of four locally relevant biochar applications: water filtration, biogas purification, soil amendment, and cooking fuel briquettes. Data was analysed at an aggregate level for all regions and applications. The study describes this consolidated biochar business model and examines the implications for SSA communities. The resulting sustainable bio-based business model can guide value chain actors and policymakers in SSA communities towards rural sustainable development with a better understanding of the needs, opportunities, challenges, and impacts of biochar-based value chain development.

Ammonia production from microalgal biosystem: Present scenario, cultivation systems, production technologies, and way forward

Recent advancements in renewable energy technologies have increased the demand for ammonia production from a variety of biomasses due to biomass’s abundant availability. Many types of biomass are used to generate biofuels by thermochemical and biochemical methods. These include residues from farming and forests, municipal solid waste, energy crops, food processing residues, industrial organic effluents, and algae. Microalgae, among the biomasses, are a valuable resource for ammonia and hydrogen production because they have a higher biomass production rate than others. It is possible to use steam gasification, pyrolysis, catalytic pyrolysis, and steam catalytic gasification to move nitrogen from algal biomass to NH3. However, intensive investigation is required in new directions to develop a mature and cost-effective technology. This article closely examines the current production of ammonia and the feasibility of utilizing algal biomass for the production of hydrogen and ammonia through various biochemical and thermochemical routes. The study comprehensively addressed the characteristics of ammonia and the current status of its production across multiple countries. The subsequent section discusses the cultivation systems and life cycle assessment of algal biomass production for fuels. Furthermore, the ammonia/hydrogen production methods utilizing algal biomass are also listed and discussed.

Exploiting Agri-Food Waste as Feed for Tenebrio molitor Larvae Rearing: A Review.

The agri-food industry generates substantial amounts of waste, including by-products and residues. The increasing demand for sustainable and eco-friendly practices in the agri-food sector has sparked an interest in finding alternative uses for such waste materials. One promising approach is the utilization of waste from the agri-food industry as feed for the rearing of mealworms (Tenebrio molitor). Since agri-food waste is rich in proteins, carbohydrates, lipids, and vitamins, as well as other bioactive compounds, all of which are essential for insect growth and development, incorporating such waste into the diet of mealworms promotes sustainable insect production, reducing the economic and environmental problems associated with waste disposal. This practice can also be beneficial for the rearing of mealworms since their nutritional value can also be enhanced. To this end, various waste materials, such as fruit and vegetable peels, spent grains, and food processing residues, have been investigated as potential feed sources, leading to increased mass production, lower cost, and enhanced nutritional value. This review aims to highlight the potential of agri-food waste as a feed source for mealworms, as well as their potential to enhance their nutritional value. Furthermore, the potential applications of mealworms reared on agri-food waste are highlighted, including their potential as a sustainable protein source for human consumption and as feed ingredients in the livestock and aquaculture sectors.

Effect of laccase extracted from fungi using food industrial residues as culture medium on degradation of chlorpyrifos in solution

Chlorpyrifos is one of the most widely used organophosphate insecticides in the world. Its extensive application has resulted in water and soil pollution and even disruption of biogeochemical cycles. In the current study, laccase extracted from the fungus Trametes versicolor using apple pomace as culture medium was used for the degradation of chlorpyrifos in solution. A series of experimental factors affecting enzyme catalysis including pH, temperature, substrate concentration, and enzyme activity were investigated as well as the enzyme degradation kinetics. Results showed that enzyme kinetic parameters such as Vmax and Km were obtained using the Michaelis-Menten equation with the values of 0.313 mg L−1 h−1 and 10.07 mg L−1, respectively. The optimal conditions for effective degradation of chlorpyrifos are pH of 2–6 and temperature of 20 °C with removal percentages of 62.2 %–67.3 % and 76.8 %, respectively. More than 50 % removal of chlorpyrifos was obtained with laccase activity higher than 250 U L−1. The findings suggest that laccase produced by fungi obtained from food processing residues could be a good candidate for chlorpyrifos degradation, especially under acid conditions. This study provides a new perspective on the biodegradation of organophosphate pesticides and a theoretical basis for the practical application of laccase in the remediation of soil and water polluted by chlorpyrifos.

Agroindustrial and food processing residues valorization for solid-state fermentation processes: A case for optimizing the co-production of hydrolytic enzymes

In the pursuit of sustainability, managing agro-industrial and food processing residues (AFR) efficiently is crucial. This study proposes a systematic approach to convert AFR into valuable products via solid-state fermentation (SSF). Using fungal enzyme production as a case study, this adaptable methodology suits any SSF bioprocess. Initially, AFR's physicochemical properties were evaluated to assess their feasible use as carbon sources and solid matrices for SSF. Then, five strains were screened for their capability to produce enzymes (Xylanase, X; pectinase, P; cellulase, C). Apple pomace (AP) and brewery spent grain (BSG) with Aspergillus sp. (strain G5) were selected. Subsequent steps involved a two-phase statistical approach, identifying critical factors and optimizing them. Process conditions were screened using a Plackett-Burman design, narrowing critical variables to three (BSG/AP, pH, humidity). Response Surface Methodology (Central Composite Design) further optimized these factors for co-synthesis of X, P, and C. The humidity had the most significant effect on the three responses. The optimum conditions depended on each enzyme and were further validated to maximize either X, P or C. The obtained extracts were used for pectin extraction from orange peels. The extract containing primarily xylanase (X = 582.39, P = 22.86, C = 26.10 U mL−1) showed major pectin yield recovery (12.33 ± 0.53%) and it was obtained using the optimal settings of BSG/AP (81/19), humidity (50.40%), and pH (4.58). The findings will enable adjusting process conditions to obtain enzymatic cocktails with a tailored composition for specific applications.

The Production of High-Added-Value Bioproducts from Non-Conventional Biomasses: An Overview

In recent decades, biomasses from different industrial segments have created new interesting perspectives, including sustainable development. Moreover, reusing waste, such as biomass, also impacts the economy, i.e., the circular economy. The main biomasses and their applications are evident in the energy, food, chemistry, fine chemical, and pharmaceutical sectors. Several questions should be asked regarding the trending topic of the circular economy, including biomass availability and seasonality, energy demand (processes), and the real environmental impact. Thus, this review focuses on biomass collected from non-conventional (unusual technology at the industrial scale) food-processing residues, particularly from 2016 to 2023, to produce biomaterials and/or bioproducts for the food sector.

Traditional breeding of small ruminants in the North-West of Benin: practices and inventory of food resources

The northern part of Benin is a favourite area for ruminant breeding in view of its pastoral resources and the many other assets it has at its disposal. The objectives of this study were (i) to characterize small ruminants rearing practices in north-western Benin, (ii) to assess factors that affect the described practices (iii) and to inventory the feed resources used in the ruminant breeding. To achieve these objectives, a retrospective survey was carried out in four municipalities located at north-west Benin. The results showed that sheep and goats are mostly raised by men (94.93%). Digestive disorders (90.41%) are the main diseases encountered. The results of linear regression analysis showed that sociocultural group and education level of the respondents have a significant influence on the mode of management and the practice of castration of small ruminants. Feeding was based on fodder from natural rangelands, notably Rottboellia cochinchinensis and Adenodolichos paniculatus. These fodders content respectively, 17.71% and 20.4% of Total Nitrogen Matter (TNM). Breeders used crop residues, notably legume tops, food processing residues and fodder trees during the lean season. In view of this multitude of food resources, possibilities for improving the existing small ruminants breeding system are proposed.

Biowaste Valorization Using Hydrothermal Carbonization for Potential Wastewater Treatment Applications

In today’s world, due to population increase, there are many alarming and potential catastrophic problems like climate change, environmental pollution and an enormous mass of wastes constantly produced by humankind to find innovative solutions for the management, recycling, and valorization of biowaste from agricultural production, food processing, and organic household residues. The search for sustainable and efficient wastewater treatment technologies has gained scientific interest recently; particular focus is on using biowaste to produce hydrochars (HCs) via the hydrothermal carbonization (HTC) process used as adsorbent materials for dye, heavy metal, and emerging pollutant removal. HTC materials derived from renewable resources are an environmentally friendly and adequate way to adsorb pollutants such as organic and inorganic molecules from wastewaters. This review focuses on the advantages of the HTC process which lead to improved properties of the materials obtained, making them highly efficient in wastewater treatment. The information presented in this paper was derived from the most recent publications in the field. Future perspectives of HC materials should consider the possibilities of scale-up, pretreatment of biowastes, and the optimal parameters of the HTC process to produce HCs applied for pollutant removal from wastewaters.

A Liposomal Formulation to Exploit the Bioactive Potential of an Extract from Graciano Grape Pomace.

Antioxidant compounds with health benefits can be found in food processing residues, such as grape pomace. In this study, antioxidants were identified and quantified in an extract obtained from Graciano red grape pomace via a green process. The antioxidant activity of the extract was assessed by the DPPH and FRAP tests, and the phenolic content by the Folin–Ciocalteu test. Furthermore, nanotechnologies were employed to produce a safe and effective formulation that would exploit the antioxidant potential of the extract for skin applications. Anthocyanins, flavan-3-ols and flavanols were the main constituents of the grape pomace extract. Phospholipid vesicles, namely liposomes, were prepared and characterized. Cryo-TEM images showed that the extract-loaded liposomes were predominantly spherical/elongated, small, unilamellar vesicles. Light scattering results revealed that the liposomes were small (~100 nm), homogeneously dispersed, and stable during storage. The non-toxicity of the liposomal formulation was demonstrated in vitro in skin cells, suggesting its possible safe use. These findings indicate that an extract with antioxidant properties can be obtained from food processing residues, and a liposomal formulation can be developed to exploit its bioactive value, resulting in a promising healthy product.

Evaluation of the Heat Produced by the Hydrothermal Liquefaction of Wet Food Processing Residues and Model Compounds

Hydrothermal liquefaction has proven itself as a promising pathway to the valorisation of low-value wet food residues. The chemistry is complex and many questions remain about the underlying mechanism of the transformation. Little is known about the heat of reaction, or even the thermal effects, of the hydrothermal liquefaction of real biomass and its constituents. This paper explores different methods to evaluate the heat released during the liquefaction of blackcurrant pomace and brewers’ spent grains. Some model compounds have also been evaluated, such as lignin, cellulose and glutamic acid. Exothermic behaviour was observed for blackcurrant pomace and brewers’ spent grains. Results obtained in a continuous reactor are similar to those obtained in a batch reactor. The heat release has been estimated between 1 MJ/kg and 3 MJ/kg for blackcurrant pomace and brewers’ spent grains, respectively. Liquefaction of cellulose and glucose also exhibit exothermic behaviour, while the transformation of lignin and glutamic acid present a slightly endothermic behaviour.

Evaluating the Presence of Lycopene-Enriched Extracts from Tomato on Topical Emulsions: Physico-Chemical Characterization and Sensory Analysis

One of the new trends of personal care industry is the use of organic ingredients derived from nature, in particular, from food-processing residues with proven efficacy. Lycopene is a carotenoid responsible for the red color of several fruits, namely tomato, whose antioxidant and photoprotective effects have been studied. Methods: Lycopene-enriched extracts (LEE) were obtained from tomato waste using supercritical CO2 extraction, incorporated in microemulsions and macroemulsions for topical use, and characterized through GC-MS for the identification of volatile compounds. The aim of this work was to evaluate the impact of the presence of lycopene-enriched extracts developed emulsions through the identification of volatile compounds and by a sensory analysis to assess the odor and color perception and the acceptability of such semi-solid systems as cosmetic products. Results: Volatile compounds were identified in the extract and in the formulations containing the extract. Preliminary data show that the odor of both LEE-loaded microemulsions and LEE-loaded macroemulsions was classified as undefined. The information about the composition did not modify the odor perception but increased the acceptability of some cosmetic products. LEE conferred a yellowish color to formulations, and the information about the formulation composition increased the likelihood of different cosmetic products with this color being bought. Conclusions: The commercialization of personal care products does not only dependent on the associated organoleptic properties, but is influenced by the information about the composition, namely by the presence of an antioxidant compound.

Lignin extraction from waste biomass with deep eutectic solvents: Molecular weight and heating value

Abstract Separating lignin from cellulose in biomass is a necessary pretreatment step prior to converting them to biofuels or bioproducts. If byproducts from food production can be separated in an ecofriendly solvent at low pressures, biomass specifically grown for biorefining will not need to be shipped long distances. Using deep eutectic solvents (DES) can separate out lignin from the non-food components remaining after agricultural production. This work investigated the efficacy of three DES on four food processing residues on lignin separation, characterizing the molecular weight and fuel value of the extracted lignins. DES pretreatments reduced molecular weight and increased the molecular weight distribution range (PDI) compared to the control black liquor derived lignin. The DES acetic acid: choline chloride (AACC) was most effective for reducing molecular weight and increasing PDI for rice husks and sugarcane bagasse, but a lactic acid: choline chloride DES improved these properties for coffee chaff, and formic acid: choline chloride DES improved them for corn stover. Higher heating values that were higher than the control black liquor derived lignin were found for lignins extracted from rice husks, sugarcane bagasse, and corn stover with AACC.

Combined Use of Solar and Biomass Energy for Sustainable and Cost-Effective Low-Temperature Drying of Food Processing Residues on Industrial-Scale

In this study, a low-temperature drying plant based on renewable energies to dry food processing wastes is investigated. The demand-oriented heat supply is realized by a solar wall in combination with a biomass boiler. Due to the operational complexity of such a system with different sub-units and process parameters, steady-state simulations were performed in Aspen Plus to provide an insight into the process. Moreover, a time-resolved energetic evaluation was conducted to analyze the influence of varying capacity of the heat sources and operational strategy in addition to economic calculations. The simulations showed that an overall control strategy needs to consider the air properties as well as the flow rate of wet input material. In the reference case, the boiler must be operated at full load through the year to supply as much heat as possible. The revenue from the dried material was the most crucial parameter on the drying economics. Although the current plant configuration operating at 12 h per day and five days per week enable feasible results, the drying process can be more profitable by doubling the boiler capacity and increasing operational hours to 24 h per day and five days per week. The proposed plant can provide an environmentally friendly and cost-effective solution for the re-valorization of food-processing wastes into added-value compounds.

Recovery and liquefaction of nitrogen-containing component and minerals from food processing wastes of vinegar using subcritical water

In recent years, environmental problems such as production of industrial waste are getting worse in Japan. In particular, food processing residues are typically disposed of by spending a large amount of money. This paper studied the treatment of two by-products from vinegar production (rice bran and sake lees) using subcritical water and analyzing the extracted solution for functional ingredients. The results from sake lees showed that an operating temperature of 180 °C and a reaction time of 30 min solubilized 85% of the nitrogen-containing component (mainly protein) from the raw material into water-soluble peptides. When rice bran was used as the raw material the solubilization rate of the nitrogen-containing components was greatly decreased at a reaction temperature of 190 °C or higher. It was shown that calcium in the raw material caused the formation of water-insoluble complexes with amino acids and ammonia such as CaCN2. Subcritical water treatment was shown to be a useful technique to recover useful water-soluble components from residual solid biomass.

Hydrothermal co-liquefaction of chlorella vulgaris with food processing residues, green waste and sewage sludge

Hydrothermal liquefaction (HTL) is a promising technology for the production of renewable biocrude from a variety of biomass. Experiments with different biogenic wastes such as sewage sludge, food and green waste and grease residue were performed to assess their suitability for hydrothermal liquefaction either as individual material or in physical mixtures with microalgae biomass (= hydrothermal co-liquefaction). The experiments were carried out in a high pressure batch autoclave at temperatures of 350 °C, a holding time of 15 min in nitrogen-atmosphere and a dry matter content of 10%. Mass balances revealed the yields of the four HTL-phases (biocrude, gaseous, solid and water phase). Additional analyses comprise Soxhlet-extraction to determine the lipid content of the raw materials, FTIR spectroscopy for HTL-gas phase composition as well as determination of calorific values and elemental compositions for raw material and respective biocrude samples. The following biocrude yields were achieved for the individual raw materials: green waste - 4.4%; sewage sludge - 12.0%; food waste - 18.2%; grease residue - 76.3%; chlorella vulgaris - 18.3%. Co-liquefaction effects for binary physical mixtures (50:50) of the biogenic residues with chlorella vulgaris could not be observed on a statistically significant basis. Hence, for the investigated samples, co-liquefaction is an option to reduce logistics costs and ensure sufficient and constant raw material mixtures for processing rather than increasing the biocrude yields by synergistic effects during Co-HTL.

Anaerobic co-digestion: a sustainable approach to food processing organic waste management

Anaerobic digestion is a promising technology to control pollution and recover energy from organic matter. In this study, batch experiments were conducted to investigate methane yields of seven organic wastes from a food processing company and dairy manure (DM) from a tie-stall barn having two straw lengths (2 cm and 10 cm) at 52 °C. This was followed by anaerobic co-digestion of all organic wastes with DM in bench experiments. The results indicated that the highest methane yield was observed in lipid-rich waste (basil sauce, 0.47 L/gVS) followed by carbohydrate-rich wastes (pumpkin processing residue, 0.21 L/gVS); the lowest yield was obtained from tomato leaves and stems (0.09 L/gVS). Furthermore, the methane yield from DM was about 0.18 L/gVS, irrespective of the straw length. Anaerobic co-digestion of food processing residues with DM demonstrated a 41% increase in methane yield (0.24 L/gVS), as compared to DM alone (0.17 L/gVS), while the milling of both organic wastes and DM did not affect methane yields. Thus, integration of anaerobic co-digestion in food processing residue management is a sustainable approach that guarantees a closed-loop flowing economy and makes food processing environmentally friendly.

Characterization of Agricultural and Food Processing Residues for Potential Rubber Filler Applications

Large volumes of agricultural and food processing residues are generated daily around the world. Despite the various potential uses reported for this biomass, most are still treated as waste that requires disposal and negatively impacts the environmental footprint of the primary production process. Increasing attention has been paid toward the use of these residues as alternative fillers for rubber and other large-scale commodity polymers to reduce dependence on petroleum. Nevertheless, characterization of these alternative fillers is required to define compatibility with the specific polymer, identify filler limitations, understand the properties of the resulting composites, and modify the materials to enable the engineering of composites to exploit all the potential advantages of these residue-derived fillers.

Theoretical and Experimental Results on the Recovery of Potato Processing Residuals by Anaerobic Digestion

Anaerobic digestion of organic matter with high moisture content has proven to be a suitable method for disposal of wet organic residuals with several advantages compared to other treatment technologies. This paper aimed at evaluating the theoretical and experimental biomethane potential of food processing residuals that are responsible for negative environmental impact, with exemplification for the potato processing waste. The biomethane potential is a useful parameter to assess the economic efficiency of anaerobic digestion processes as it can considerably influence the efficiency and the economic feasibility of the energy recovery technologies. Both experimental and theoretical biomethane potentials of potato waste in mesophilic anaerobic digestion as well as biodegradability of the substrate were estimated. Moreover, effects of microalgal extract addition on the digestion of potato waste were examined in an attempt to stimulate the anaerobic digestion. Cone model and a modified Gompertz model were used to predict the dynamics of biomethane production.

Potato Peel as a Sustainable Resource of Natural Antioxidants for the Food Industry

Upgrading of food processing residues is currently a topic of global interest as scientists and industries have focused on using natural sources of antioxidants as an alternative to synthetic ones. The aim of the present work was to assess the potential of potato peel extracts of cultivars Gala and Jazzy in 96% ethanol, 80% ethanol and water by using antioxidant assays as well as model systems that contained food lipids. Extracts in 96% ethanol contained the highest amount of total phenolics (40.5 and 28.4 mg/g of dry weight) and showed the highest antiradical, reducing and iron-chelating potential, followed by extracts in 80% ethanol. The order of the extracts’ activity in β-carotene bleaching assay was strongly concentration-dependent. Potato peel extracts showed high efficiency in retarding oxidation of rapeseed oil, where they performed better than butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). They also delayed conjugated diene and volatile formation in sunflower oil. Compounds of potato peel extracts act via several mechanisms, assuring long-term protection of food lipids. They are a promising source of antioxidants that should be chosen carefully for a given medium in order to be stabilized and to obtain optimal results. The manner of potato peel valorization proposed here is in line with the global challenge to reduce food production waste residues and also gives an opportunity to extend the shelf life of food.