Pilot‐Plant Proof‐of‐Concept for Integrated, Countercurrent, Two‐Stage, Enzyme‐Assisted Aqueous Extraction of Soybeans

From a Single-Stage to a Two-Stage Countercurrent Extraction of Lipids and Proteins from Full-Fat Chickpea Flour: Maximizing Process Extractability and Economic Feasibility

The mainstream adoption of chickpea proteins and lipids requires a thorough understanding of the impact of critical extraction parameters (enzyme use, reaction time, and solids-to-liquid ratio—SLR) and modes of extraction (single-stage extraction—SSE and countercurrent extraction—CCE) on the simultaneous extraction of lipids and proteins from full-fat chickpea flour and economic process feasibility. A kinetics study revealed that 68.5% oil and 87% protein extraction yields can be achieved using 0.5% protease at pH 9.0, 50 °C, 60 min, and 1:10 SLR, highlighting the role of proteolysis and an adequate incubation time on overall extractability. An increased gradient concentration between the matrix and aqueous media solutes at a lower SLR (1:15), and reduced slurry viscosity increased oil and protein extractability to 80 and 91%, respectively. The high-water usage in the SSE was addressed by the development of a two-stage CCE that reduced water usage by 47% while increasing oil and protein extractability to ~96%. Higher extractability and reduced water usage in the two-stage CCE resulted in a higher net gross profit, thus outweighing its higher operating costs. The results presented herein further widen the scope of bioprocessing standards for full-fat chickpea flour and add to the elucidation of the impact of key processing conditions on the extractability and economic feasibility of the production of chickpea ingredients for subsequent food/nutraceutical applications.

Leveraging Bioprocessing Strategies to Achieve the Simultaneous Extraction of Full-Fat Chickpea Flour Macronutrients and Enhance Protein and Carbohydrate Functionality

The concurrent extraction of lipids, proteins, and carbohydrates can be achieved by aqueous and enzymatic extraction processes, circumventing the low extractability by mechanical pressing and the use of flammable solvents. The use of alkaline protease, preceded or not by carbohydrase pretreatments, was evaluated on the extractability of oil, protein, and carbohydrates from full-fat chickpea flour and protein functionality. Enzymatic extraction increased oil and protein extractability from 49.8 to 72.0–77.1% and 62.8 to 83.5–86.1%, respectively. Although the carbohydrase pretreatments before the addition of protease did not increase oil and protein extractability, the carbohydrate content of the extracts increased from 7.68 to 9.17−9.33 mg/mL, accompanied by the release of new oligosaccharides in the extracts, as revealed by LC–MS/MS characterization. Enzymatic extraction yielded proteins with significantly higher solubility (25.6 vs. 68.2–73.6%) and digestibility (83.8 vs. 90.79–94.67%). Treatment of the extracts with α-galactosidase completely removed the flatulence-causing oligosaccharides (stachyose and raffinose). This study highlights the effectiveness of environmentally friendly bioprocessing strategies to maximize lipid, protein, and oligosaccharide extractability from full-fat chickpea flour with concurrent improvements in protein solubility and in vitro digestibility, reduction of flatulence related oligosaccharides, and generation of a more diverse pool of oligosaccharides for subsequent prebiotic evaluation.

Graphical abstract

The Formation, Stabilization and Separation of Oil–Water Emulsions: A Review

Oil–water emulsions are widely generated in industries, which may facilitate some processes (e.g., transportation of heavy oil, storage of milk, synthesis of chemicals or materials, etc.) or lead to serious upgrading or environmental issues (e.g., pipeline plugging, corrosions to equipment, water pollution, soil pollution, etc.). Herein, the sources, classification, formation, stabilization, and separation of oil–water emulsions are systematically summarized. The roles of different interfacially active materials–especially the fine particles–in stabilizing the emulsions have been discussed. The advanced development of micro force measurement technologies for oil–water emulsion investigation has also been presented. To provide insights for future industrial application, the separation of oil–water emulsions by different methods are summarized, as well as the introduction of some industrial equipment and advanced combined processes. The gaps between some demulsification processes and industrial applications are also touched upon. Finally, the development perspectives of oil–water treatment technology are discussed for the purpose of achieving high-efficiency, energy-saving, and multi-functional treatment. We hope this review could bring forward the challenges and opportunities for future research in the fields of petroleum production, coal production, iron making, and environmental protection, etc.

Enzymatic pretreatment in the extraction process of soybean to improve protein and isoflavone recovery and to favor aglycone formation

This research aimed to evaluate the pretreatment of soybean with the carbohydrase multi-enzyme complex "Viscozyme L", during the extraction process; in order to improve the recovery of proteins and isoflavones in soybase, and reduce the loss of these compounds through the okara residue. Three concentrations of enzyme were studied at 50 °C, along with an experiment carried out without enzyme addition (control experiment). The results were also evaluated in relation to standard soybase processing. In comparison to the standard and control processes, the enzymatic pretreatment reduced up to 85% the total amount of okara residue. Due to the action of the multi-enzyme complex, protein and total isoflavone recovery increased from 42% to 83% and from 59% to 93%, respectively. The application of Viscozyme L also favored the conversion of conjugated forms of isoflavone to aglycone in the soybase, representing up to 50% of the total isoflavones. The enzymatic pretreatment of soybean with carbohydrase improved the nutritional quality of the soybase, while at the same time reducing residue generation; showing that the proposed food process can be considered environmentally friendly method.

Effect of co-products of enzyme-assisted aqueous extraction of soybeans on ethanol production in dry-grind corn fermentation

Enzyme-assisted aqueous extraction processing (EAEP) is an environmentally-friendly alternative to solvent and mechanical oil extraction methods, and can achieve ∼ 97% oil recovery from soybeans. The present study utilized soy skim (protein rich) and insoluble fiber (IF; carbohydrate rich), both co-products of EAEP, in dry-grind corn fermentation. The effects of adding soy skim and untreated IF (UIF), either separately or together, and adding pretreated IF (TIF), on ethanol production were investigated. Maximum ethanol production was achieved when UIF and skim were slurried together (corn-to-UIF ratio 1:0.16; skim-to-UIF ratio 6.5:1) and when fiber-hydrolyzing enzymes were added to corn fermentation. This modification to corn fermentation increased ethanol yield by 20%, ethanol production rate by 3%, and decreased fermentation time by 38 h compared to corn-only fermentation. An attempt was also made to utilize pentoses (from soy skim and IF) in integrated corn-soy fermentation slurry by an additional Escherichia coli KO11 fermentation step.

Pythium irregulare fermentation to produce arachidonic acid (ARA) and eicosapentaenoic acid (EPA) using soybean processing co-products as substrates

Arachidonic acid (ARA) and eicosapentaenoic acid (EPA) were produced by Pythium irregulare fungus using soybean cotyledon fiber and soy skim, two co-products from soybean aqueous processing, as substrates in different fermentation systems. Parameters such as moisture content, substrate glucose addition, incubation time, and vegetable oil supplementation were found to be important in solid-state fermentation (SSF) of soybean fiber, which is to be used as animal feed with enriched long-chain polyunsaturated fatty acids (PUFA). Soybean fiber with 8 % (dwb) glucose supplementation for a 7-day SSF produced 1.3 mg of ARA and 1.6 mg of EPA in 1 g of dried substrate. When soy skim was used as substrate for submerged fermentation, total ARA yield of 125.7 mg/L and EPA yield of 92.4 mg/L were achieved with the supplementation of 7 % (w/v) soybean oil. This study demonstrates that the values of soybean fiber and soy skim co-products could be enhanced through the long-chain PUFA production by fermentation.

Effects of fermentation substrate conditions on corn-soy co-fermentation for fuel ethanol production

Soy skim, a protein-rich liquid co-product from the aqueous extraction of soybeans, was co-fermented with corn to produce ethanol. Effects of soy skim addition level, type of skim, corn particle size, water-to-solids ratio, and urea on co-fermentation were determined. The addition of 20-100% skim increased the fermentation rate by 18-27% and shortened the fermentation time by 5-7h without affecting ethanol yield. Finely ground corn or high water-to-solids ratio (≥ 3.0) in the mash gave higher fermentation rates, but did not increase the ethanol yield. When the water was completely replaced with soy skim, the addition of urea became unnecessary. Soy skim retentate that was concentrated by nanofiltration increased fermentation rate by 25%. The highest level of skim addition resulted in a finished beer with 16% solids, 47% protein (dwb) containing 3.6% lysine, and an ethanol yield of 39 g/100g dry corn.

Solid-state fermentation of soybean and corn processing coproducts for potential feed improvement

Two agro-industrial coproducts, soybean cotyledon fiber and distiller's dried grains with solubles (DDGS), were used as substrates to evaluate the effect of coculturing three different fungi, Aspergillus oryzae, Trichoderma reesei, and Phanerochaete chrysosporium, on enzyme production by solid-state fermentation (SSF). When soybean fiber was used as the substrate, a maximum xylanase activity of 757.4 IU/g and a cellulase activity of 3.2 IU/g were achieved with the inoculation and incubation of T. reesei and P. chrysosporium for 36 h, followed by A. oryzae for an additional 108 h. This inoculation scheme also resulted in the highest xylanase activity of 399.2 IU/g compared to other fungi combinations in the SSF of DDGS. A large-scale SSF by this fungus combination produced fermented products that had xylanase and cellulase activities of 35.9-57.0 and 0.4-1.2 IU/g, respectively. These products also had 3.5-15.1% lower fiber and 1.3-4.2% higher protein contents, suggesting a potential feed quality improvement.