A review of okara (soybean curd residue) utilization as animal feed: Nutritive value and animal performance aspects

Impacts of industrial food wastes on nutritional value of mealworm (Tenebrio molitor) and its gut microbiota community shift

The extensive investigation into the capacity of mealworms to digest diverse food by-products, as well as plastic wastes, has been a focal point in recent years. The transition from traditional diet sources like brans to food wastes has the potential to impact the physiological properties of mealworms. This study explored the utilization of various industrial food wastes such as okara, barley spent grain (BSG), sesame oil meal (SOM), and spent coffee grounds (SCG) as feed alternatives, and reports on their survival rate, biomass variations, and nutritional composition. In additional, the shift in their gut microbiota was also assessed. Among the range of industrial food wastes, mealworms exhibited the most robust growth performance when nourished with BSG. This particular group showed a survival rate of 98.33 % and a biomass increase of 23.06 %. In contrast, mealworms fed with SCG demonstrated the lowest survival rate and experienced a significant reduction in biomass. Although the groups fed with okara and SCG displayed moderate growth performance, both exhibited protein levels comparable to those observed in the oatmeal-fed group (used as the positive control). Notably, the inclusion of BSG in the mealworm diet exhibited the potential to enrich their omega-3 fatty acid content, suggesting potential benefits for applications as animal feed or even human consumption. Furthermore, an analysis of the gut microbiome was conducted to investigate the associations between specific diets and the composition of mealworm gut microbiota. In summary, food wastes such as BSG may be repurposed as feed substrates for mealworms before converting them into an alternative source of protein.

Exploring the Potential of Aspergillus oryzae for Sustainable Mycoprotein Production Using Okara and Soy Whey as Cost-Effective Substrates

Mycoprotein is an alternative protein produced through fungal fermentation. However, it typically relies on refined glucose syrup derived from starch, which can be costly and unsustainable. This study investigates the potential of soybean processing by-products (okara and soy whey) as alternative substrates for producing mycoprotein using Aspergillus oryzae. A. oryzae was cultured for 7 days at 30 °C in diluted okara (1:50) and soy whey (1:1) with or without agitation (100 rpm). Soy whey produced higher biomass yields (369.2-408.8 mg dry biomass/g dry substrate), but had a lower biomass concentration (0.783-0.867 g dry weight/L). Conversely, okara produced a higher biomass concentration (2.02 g dry weight/L) with a yield of 114.7 mg dry biomass/g dry substrate. However, biomass formation in okara was only observed in static conditions, as agitation caused biomass to entangle with soy pulp, hampering its production. Additionally, okara tended to release protein into the media, while soy whey accumulated protein within the biomass, reaching up to 53% w/w protein content. The results of this study provide a promising approach to addressing both soybean processing waste reduction and food security concerns.

Upgrading soybean dreg to caproate via intermediate of lactate and mediator of biochar

To address the environmental hazards posed by high-yield soybean dreg (SD), a high-value strategy is firstly proposed by synthesizing caproate through chain elongation (CE). Optimized conditions for lactate-rich broth as intermediate, utilizing 50 % inoculum ratio, 40 g/L substrate concentration, and pH 5, resulting in 2.05 g/L caproate from direct fermentation. Leveraging lactate-rich broth supplemented with ethanol, caproate was optimized to 2.76 g/L under a refined electron donor to acceptor of 2:1. Furthermore, incorporating 20 g/L biochar elevated caproate production to 3.05 g/L and significantly shortened the lag phase. Mechanistic insights revealed that biochar's surface-existed quinone and hydroquinone groups exhibit potent redox characteristics, thereby facilitating electron transfer. Moreover, biochar up-regulated the abundance of key genes involved in CE process (especially fatty acids biosynthesis pathway), also enriching Lysinibacillus and Pseudomonas as an unrecognized cooperation to CE. This study paves a way for sustainable development of SD by upgrading to caproate.

Saline as solvent and ethanol-based purification process for the extraction of proteins and isoflavones from wet okara

Okara, the solid byproduct of water-soluble soybean extract production, is a potential source of proteins and isoflavones. This study investigated different experimental configurations for extracting these compounds from wet okara, including lipid removal with ethanol at different stages of the recovery process, sequential crosscurrent extraction, and using a saline MgCl2 solution as the solvent. Three washes with a 60:40 ethanol:water (w/w) solution after isoelectric precipitation significantly increased protein content by reducing lipid content (60 %). The crosscurrent approach using 0.05 M MgCl2 yielded okara proteinaceous material with 248 µg/g daidzein and 236 µg/g genistein, along with a 3 % increase in protein content, attributed to enhanced extraction of 7S globulins. These configurations notably affected the functional properties of the protein materials. Overall, this research provides detailed insights into the composition and properties of proteins extracted from wet okara, facilitating their specialized application in food products.

From Soy Waste to Bioplastics: Industrial Proof of Concept

The global plastic waste problem is pushing for the development of sustainable alternatives, encouraged by stringent regulations combined with increased environmental consciousness. In response, this study presents an industrial-scale proof of concept to produce self-standing, transparent, and flexible bioplastic films, offering a possible solution to plastic pollution and resource valorization. We achieve this by combining amyloid fibrils self-assembled from food waste with methylcellulose and glycerol. Specifically, soy whey and okara, two pivotal protein-rich byproducts of tofu manufacturing, emerge as sustainable and versatile precursors for amyloid fibril formation and bioplastic development. An exhaustive industrial-scale feasibility study involving the transformation of 500 L of soy whey into ∼1 km (27 kg) of bioplastic films underscores the potential of this technology. To extend the practicality of our approach, we further processed a running kilometer of film at the industrial scale into transparent windows for paper-based packaging. The mechanical properties and the water interactions of the novel film are tested and compared with those of commercially used plastic films. By pioneering the large-scale production of biodegradable bioplastics sourced from food byproducts, this work not only simultaneously addresses the dual challenges of plastic pollution and food waste but also practically demonstrates the feasibility of biopolymeric building block valorization for the development of sustainable materials in real-world scenarios.

Total Replacement of Soybean Meal with Sundried Soymilk Residue in the Total Mixed Ration has a Negative Impact on Intake, Digestibility, and Milk Production in Dairy Goats

This study aimed to evaluate whether total replacement of soybean meal (SBM) with sundried soymilk residue (SSR) in a total mixed ration (TMR) affects intake, digestibility, milk production, and blood metabolites in dairy goats. A total of 12 healthy Saanen dairy goats (40.12 ± 5.80 kg of BW) in midlactation (31.23 ± 10.12 days) were used in a randomized complete design (n = 4 goats/group). Dietary treatments were based on a TMR as follows: control TMR without SSR (CON) or SBM-based TMR with 50% or 100% of SSR replacing SBM (SSR-50 and SSR-100, respectively). All goats had ad libitum access to feed and clean water throughout the experiment. The dry matter (DM) intake decreased (p < 0.05) with the increasing replacement ratio of SBM and was lowest in the SSR-100 group. Similarly, organic matter (OM) digestibility was lowest (p < 0.05) in the SSR-100 group. However, the digestibility of DM, CP, NDF, and ADF did not change (p > 0.05) by dietary treatments. Compared with CON, the milk yield decreased significantly (p < 0.05) with increasing replacement ratio of SBM. In contrast, milk composition such as total solids, solids-not-fat, milk fat, lactose, protein, and pH were not influenced (p > 0.05) by feeding dietary SSR. Compared with other treatments, blood glucose concentration was lower (p < 0.05) in the SSR-100 group. In contrast, packed cell volume, glucose, and plasma urea nitrogen concentrations did not differ (p > 0.05). The results indicated that SSR could replace SBM in a TMR at less than 50%. Thus, the present study provides support for further investigation to enhance the utilization of soybean waste as an alternative protein source in the TMR for dairy goats and potentially other ruminants.

Triple-transgenic soybean in conjunction with glyphosate drive patterns in the rhizosphere microbial community assembly

Plant roots continuously influence the rhizosphere, which also serves as a recruitment site for microorganisms with desirable functions. The development of genetically engineered (GE) crop varieties has offered unparalleled yield advantages. However, in-depth research on the effects of GE crops on the rhizosphere microbiome is currently insufficient. We used a triple-transgenic soybean cultivar (JD606) that is resistant to insects, glyphosate, and drought, along with its control, ZP661, and JD606 treated with glyphosate (JD606G). Using 16S and ITS rDNA sequencing, their effects on the taxonomy and function of the bacterial and fungal communities in the rhizosphere, surrounding, and bulk soil compartment niches were determined. Alpha diversity demonstrated a strong influence of JD606 and JD606G on bacterial Shannon diversity. Both treatments significantly altered the soil's pH and nitrogen content. Beta diversity identified the soil compartment niche as a key factor with a significant probability of influencing the bacterial and fungal communities associated with soybeans. Further analysis showed that the rhizosphere effect had a considerable impact on bacterial communities in JD606 and JD606G soils but not on fungal communities. Microbacterium, Bradyrhizobium, and Chryseobacterium were found as key rhizobacterial nodes. In addition, the LEfSe analysis identified biomarker taxa with plant-beneficial attributes, demonstrating rhizosphere-driven microbial recruitment. FUNGuild, Bugbase, and FAPROTAX functional predictions showed that ZP661 soils had more plant pathogen-associated microbes, while JD606 and JD606G soils had more stress-tolerance, nitrogen, and carbon cycle-related microbes. Bacterial rhizosphere networks had more intricate topologies than fungal networks. Furthermore, correlation analysis revealed that the bacteria and fungi with higher abundances exhibited varying degrees of positive and negative correlations. Our findings shed new light on the niche partitioning of bacterial and fungal communities in soil. It also indicates that following triple-transgenic soybean cultivation and glyphosate application, plant roots recruit microbes with beneficial taxonomic and functional traits in the rhizosphere.

Impacts of Ultrasonic Treatment for Black Soybean Okara Culture Medium Containing Choline Chloride on the β-Glucosidase Activity of Lactiplantibacillus plantarum BCRC 10357

The effects of ultrasonic treatment for the culture medium of solid black soybean okara with choline chloride (ChCl) on the survival and β-glucosidase activity of Lactiplantibacillus plantarum BCRC 10357 (Lp-BCRC10357) were investigated. A mixture of 3% dried black soybean okara in de Man-Rogosa-Sharpe (w/v) was used as the Oka medium. With ultrasonic treatment (40 kHz/300 W) of the Oka medium at 60 °C for 3 h before inoculation, the β-glucosidase activity of Lp-BCRC10357 at 12 h and 24 h of incubation amounted to 13.35 and 15.50 U/mL, respectively, which was significantly larger than that (12.58 U/mL at 12 h and 2.86 U/mL at 24 h) without ultrasonic treatment of the medium. This indicated that ultrasonic treatment could cause the microstructure of the solid black soybean okara to be broken, facilitating the transport of ingredients and Lp-BCRC10357 into the internal structure of the okara for utilization. For the effect of ChCl (1, 3, or 5%) added to the Oka medium (w/v) with ultrasonic treatment before inoculation, using 1% ChCl in the Oka medium could stimulate the best response of Lp-BCRC10357 with the highest β-glucosidase activity of 19.47 U/mL in 12 h of incubation, showing that Lp-BCRC10357 had a positive response when confronting the extra ChCl that acted as an osmoprotectant and nano-crowder in the extracellular environment. Furthermore, the Oka medium containing 1% ChCl with ultrasonic treatment led to higher β-glucosidase activity of Lp-BCRC10357 than that without ultrasonic treatment, demonstrating that the ultrasonic treatment could enhance the contact of ChCl and Lp-BCRC10357 to regulate the physiological behavior for the release of enzymes. In addition, the analysis of the isoflavone content and antioxidant activity of the fermented product revealed that the addition of 1% ChCl in the Oka medium with ultrasonic treatment before inoculation allowed a higher enhancement ratio for the biotransformation of isoflavone glycosides to their aglycones, with a slight enhancement in the antioxidant activity at 24 h of fermentation. This study developed a methodology by combining ultrasonic treatment with a limited amount of ChCl to allow the culture medium to acclimate Lp-BCRC10357 and release high levels of β-glucosidase, and this approach has the potential to be used in the fermentation of okara-related products as nutritional supplements in foods.

Aerated Static Pile Composting for Industrial Biowastes: From Engineering to Microbiology

This work demonstrated the feasibility of an industrial-scale aerated static pile composting system for treating one of the common biowastes-soybean curd residue. The mixing ratios of the feedstock were optimized to achieve a carbon-nitrogen ratio and a moisture level in the ranges of 25-35 and 60-70%, respectively. This open-air composting system required 6-7 months to obtain a mature compost. Solvita and seed germination tests further confirmed the maturity of the compost, with 25% compost extract concentration yielding the best germination index in the absence of phytotoxicity. The bacterial and fungal compositions of the compost piles were further examined with metagenomic analysis. Thermoactinomyces spp., Oceanobacillus spp., and Kroppenstedtia spp. were among the unique bacteria found, and Diutina rugosa, Thermomyces dupontii, and Candida taylorii were among the unique fungi found in the compost piles, suggesting the presence of good microorganisms for degrading the organic biowastes.

Valorization and food applications of okara (soybean residue): A concurrent review

Agriculture waste is rising continuously across the globe due to enormous industrial, food processing, and household activities. Proper valorization of this waste could be a promising source of various essential bioactive and functional ingredients. Okara is a major residue produced as result of soybean processing and has a rich nutritional profile. The nutritional profile of okara is affected by the processing conditions, variety, pre-treatment, post-production treatments, and processing techniques. Owing to the high fibers, lipids, proteins, and bioactive components, it is being used as an essential industrial ingredient in various food processing industries. The prebiotic potential and nutritional profile can be increased by various techniques, that is, enzymatic, chemical, biotransformation, high-pressure microfludization, and fermentation. The prebiotic potential of okara makes it suitable as a therapeutic agent to prevent a variety of metabolic disorders such as diabetes, obesity, hypercholesterolemia, and hyperlipidemia. The current review highlights the structural, nutritional, functional, therapeutic, and industrial applications of okara.

A narrative action on the battle against hunger using mushroom, peanut, and soybean-based wastes

Numerous generations have been affected by hunger, which still affects hundreds of millions of people worldwide. The hunger crisis is worsening although many efforts have been made to minimize it. Besides that, food waste is one of the critical problems faced by most countries worldwide. It has disrupted the food chain system due to inefficient waste management, while negatively impacting the environment. The majority of the waste is from the food production process, resulting in a net zero production for food manufacturers while also harnessing its potential. Most food production wastes are high in nutritional and functional values, yet most of them end up as low-cost animal feed and plant fertilizers. This review identified key emerging wastes from the production line of mushroom, peanut, and soybean (MPS). These wastes (MPS) provide a new source for food conversion due to their high nutritional content, which contributes to a circular economy in the post-pandemic era and ensures food security. In order to achieve carbon neutrality and effective waste management for the production of alternative foods, biotechnological processes such as digestive, fermentative, and enzymatic conversions are essential. The article provides a narrative action on the critical potential application and challenges of MPS as future foods in the battle against hunger.

Turning Food Protein Waste into Sustainable Technologies

For each kilogram of food protein wasted, between 15 and 750 kg of CO2 end up in the atmosphere. With this alarming carbon footprint, food protein waste not only contributes to climate change but also significantly impacts other environmental boundaries, such as nitrogen and phosphorus cycles, global freshwater use, change in land composition, chemical pollution, and biodiversity loss. This contrasts sharply with both the high nutritional value of proteins, as well as their unique chemical and physical versatility, which enable their use in new materials and innovative technologies. In this review, we discuss how food protein waste can be efficiently valorized not only by reintroduction into the food chain supply but also as a template for the development of sustainable technologies by allowing it to exit the food-value chain, thus alleviating some of the most urgent global challenges. We showcase three technologies of immediate significance and environmental impact: biodegradable plastics, water purification, and renewable energy. We discuss, by carefully reviewing the current state of the art, how proteins extracted from food waste can be valorized into key players to facilitate these technologies. We furthermore support analysis of the extant literature by original life cycle assessment (LCA) examples run ad hoc on both plant and animal waste proteins in the context of the technologies considered, and against realistic benchmarks, to quantitatively demonstrate their efficacy and potential. We finally conclude the review with an outlook on how such a comprehensive management of food protein waste is anticipated to transform its carbon footprint from positive to negative and, more generally, have a favorable impact on several other important planetary boundaries.

Chemical composition, in vitro digestibility, and storability of selected agro-industrial by-products: Alternative ruminant feed ingredients in Israel

The global demand for animal-based products is rising in the face of dwindling feed resources, and yet a huge pool of agro-industrial by-products (AIBPs) are generated, underutilized, and improperly deposited to landfills leading to environmental pollution. Ruminants have a special microbiome that can bioprocess and convert human inedible fibrous material into meat and milk, which appears as a great opportunity to simultaneously reduce pollution while promoting food security. In this study, we collected 15 domestically produced AIBPs from various regions of Israel during both winter and summer seasons to examine their potential as ruminant feed alternatives. We evaluated their storability, nutritional composition, and in vitro digestibility and performed a hierarchical cluster analysis to categorize them based on their distinctive nutritional characteristics. Among the 15 AIBPs, 8 have rich essential nutrients, and minerals, and have excellent in vitro digestibility, but they have less than 6 days of storability and develop off-odours. Out of 15 AIBPs; 8 have low dry matter (DM) content, ranging from 4.7% to 30.45% while the remaining 7 AIBPs have high DM, ranging from 50.6% to 98.6%. The high crude protein (CP) category included 6 AIBPs with CP ranging from 19.7% in beer pulp to 32.1% in jojoba cake. Starch content was high in 3 AIBPs ranging from 33.7% in timorim mix to 65.2% in Irish potato culls. Considerable crude fat content was reported in 4 AIBPs, the highest being yoghurt waste with 42.8%. In terms of neutral detergent fiber (NDF), 5 AIBPs had low NDF content ranging from 0% to 14.1%; 5 AIBPs had moderate concentration ranging from 34.3% to 50.7%, and 5 AIBPs had high levels between 66.6% and 82.8%. Interestingly, 10/15 AIBPs had medium to high in vitro dry matter digestibility (IVDMD). This study, therefore, suggests that recycling AIPBs for livestock nutrition has enormous potential that is still underutilized and offers excellent ways to gain socioeconomic and environmental benefits by expanding animal feed resources and reducing feed-food competition, and landfill burden. However, additional studies are necessary to focus on affordable storage technology to prolong the storability of AIBPs and feeding trials to determine the productive performance of livestock fed an AIBPs-based diet.

Recent Advances, Challenges, Opportunities, Product Development and Sustainability of Main Agricultural Wastes for the Aquaculture Feed Industry – A Review

Million tonnes of agricultural waste are generated annually worldwide. Agricultural wastes possess similar profiles to the main products but are lower in quality. Managing these agricultural wastes is costly and requires strict regulation to minimise environmental stress. Thus, these by-products could be repurposed for industrial use, such as alternative resources for aquafeed to reduce reliance on fish meal and soybean meal, fertilisers to enrich medium for growing live feed, antimicrobial agents, and immunostimulatory enhancers. Furthermore, utilising agricultural wastes and other products can help mitigate the existing environmental and economic dilemmas. Therefore, transforming these agricultural wastes into valuable products helps sustain the agricultural industry, minimises environmental impacts, and benefits industry players. Aquaculture is an important sector to supply affordable protein sources for billions worldwide. Thus, it is essential to explore inexpensive and sustainable resources to enhance aquaculture production and minimise environmental and public health impacts. Additionally, researchers and farmers need to understand the elements involved in new product development, particularly the production of novel innovations, to provide the highest quality products for consumers. In summary, agriculture waste is a valuable resource for the aquafeed industry that depends on several factors: formulation, costing, supply, feed treatment and nutritional value.

Ecofriendly Usability of Mushroom Cultivation Substrate as a Ruminant Feed: Anaerobic Digestion Using Gas Production Techniques

The current study was carried out to evaluate the nutritive value of mushroom-uncultivated and -cultivated substrates, and their in vitro gas and methane production. The experiment was conducted in a completely randomized design, and analyzed with GLM using SAS 9.4. Analysis of the structural morphology of mushroom-cultivated substrate was performed using a scanning electron microscope. Mushroom cultivation led to lower ether extract, acid detergent fiber, and crude fiber level of substrate (p < 0.05). Mushroom-cultivated substrate showed higher in vitro cumulative gas production (p < 0.05). Moreover, mushroom cultivation led to a higher sample surface, and improved the microorganisms’ access to feed materials, thus stimulating rumen fermentation and increasing methane production (p < 0.05). The organic matter digestibility, metabolizable energy, and net energy lactation values were higher for mushroom-cultivated substrate than uncultivated substrate. The results demonstrate that mushroom-cultivation not only increases the contact surface of cellulose, leading to higher ruminal microorganisms’ access to feedstuff, but could also had higher nutritive value; this material might be used in ruminant ration formulation, to reduce environmental pollution and feed costs.

Fermentation Quality and Microbial Community of Corn Stover or Rice Straw Silage Mixed with Soybean Curd Residue

The objective of this study was to investigate the fermentation quality and microbial community of corn stover (CS) or rice straw (RS) silage mixed with soybean curd residue (SCR). In this study, SCR and CS or RS were mixed at ratios of 75:25, 70:30, and 65:35, respectively, and measured for nutrient content, fermentation indices, and bacterial diversity after 30 days of ensiling. The results showed an increase in lactic acid (LA) concentration (p < 0.01) and crude protein (CP) content (p < 0.0001), a decrease in pH value (p < 0.01), the content of NDF (p < 0.01) and ADF (p < 0.01), and ammonia nitrogen (AN) concentration (p < 0.01) as the proportion of SCR in raw materials (CS or RS) increased. The addition of SCR to silage led to a decrease in bacterial diversity and contributed to an increased relative abundance of beneficial microorganisms, such as Lactobacillus, and a corresponding decrease in the relative abundance of undesirable microorganisms, such as Clostridium and Enterobacter. Collectively, the mixed silage of soybean curd residue with corn stover or rice straw preserved more nutrients and helped improve fermentation quality.

Effects of the inclusion of black soldier fly larvae (Hermetia illucens) meal on growth performance and blood plasma constituents in broiler chicken (Gallus gallus domesticus) production

The aim of this study was to identify the effect of inclusion of defatted black soldier fly larvae (Def-BSFL) meal as a protein source on the performance and blood plasma constituents of broiler chickens. A total of 360-day-old chicks were assigned into four dietary groups, which included four different levels of Def-BSFL meal namely control (0% BSFL), T1(4% BSFL), T2 (8% BSFL) and T3 (12% BSFL) for six weeks experimental feeding period. At the end of the experiment, the blood samples of three birds from each treatment were collected to measure plasma constituents. Birds fed control and T1 diets demonstrated higher feed intake during the finisher stage compared with T2 and T3 diets. The heaviest weight for the 6-week feeding trial was recorded at T1 (1043.8 ± 65.9 g). Birds fed T1 (1.1 ± 0.0) and T3 (0.9 ± 0.1) diets displayed lower feed conversion ratio during the finisher stage than those fed control (1.7 ± 0.1) and T2 (1.8 ± 0.3) diets. Birds fed the control diet demonstrated the highest red blood cell with mean and standard deviation of 7.5 ± 0.34, whereas those fed the T2 diet showed the highest haemoglobin levels with mean and standard deviation of 15.8 ± 0.24. Birds fed T1, T2, and T3 diets exhibited a higher number (P < 0.05) of monocytes than those fed a control diet. There were no differences in white blood cell count across all the groups. In addition, birds fed the T2 diet showed higher (P < 0.05) blood urea nitrogen followed by the T3, control, and T1 diets. As a conclusion, the 4% Def-BSFL in the broiler chicken diet could be used to replace fish meal (FM) and soybean meal (SBM) without compromising bird performance and blood traits.