Effects of solid-state fermentation and proteolytic hydrolysis on defatted soybean meal

Combined Effects of Lactic Acid Bacteria and Protease on the Fermentation Quality and Microbial Community during 50 Kg Soybean Meal Fermentation Simulating Actual Production Scale

The improvement in the utilization rate and nutritional value of soybean meal (SBM) represents a significant challenge in the feed industry. This study conducted a 50 kg SBM fermentation based on the 300 g small-scale fermentation of SBM in early laboratory research, to explore the combined effects of lactic acid bacteria (LAB) and acid protease on fermentation quality, chemical composition, microbial population, and macromolecular protein degradation during fermentation and aerobic exposure of SBM in simulated actual production. The results demonstrated that the increase in crude protein content and reduction in crude fiber content were considerably more pronounced after fermentation for 30 days (d) and subsequent aerobic exposure, compared to 3 d. It is also noteworthy that the treated group exhibited a greater degree of macromolecular protein degradation relative to the control and 30 d of fermentation relative to 3 d. Furthermore, after 30 d of fermentation, adding LAB and protease significantly inhibited the growth of undesired microbes including coliform bacteria and aerobic bacteria. In the mixed group, the microbial diversity decreased significantly, and Firmicutes replaced Cyanobacteria for bacteria in both groups' fermentation.

Alcalase-hydrolyzed insoluble soybean meal hydrolysate aggregates: Structure, bioactivity, function properties, and influences on the stability of oil-in-water emulsions

We studied the influences of hydrolysis time on the structure, functional properties, and emulsion stability of insoluble soybean meal hydrolysate aggregates (ISMHAs). We assume that the ISMHAs produced by soybean meal can be used as emulsifiers to prepare stable emulsions. The molecular weights of these ISMHAs were below 53 kDa. After hydrolysis, a decrease in α-helices and an increase in random coils indicated that the soybean meal proteins were unfolding. Moreover, the fluorescence intensity, UV absorption, and surface hydrophobicity of ISMHAs increased. These results would contribute to their antioxidant activity and functional properties. Additionally, the 90-min ISMHA sample exhibited the highest ABTS+• scavenging activity (80.02 ± 4.55 %), foaming stability (52.92 ± 8.06 %), and emulsifying properties (emulsifying activity index of 97.09 m2/g; emulsifying stability index of 371.47 min). The 90-min ISMHA emulsion exhibited the smallest particle size and excellent storage stability. Soybean meal peptide by-product emulsifier has potential for sustainable application.

Protein digestibility and ACE inhibitory activity of fermented flours in older adults and standard gastrointestinal simulation

Consumption of essential amino acids responsible for muscle protein synthesis is important in preventing sarcopenia among older individuals. This population may experience gastrointestinal disorders that inhibit protein digestibility, making it crucial to address. Therefore, solid-state fermentation (SSF) using Pleurotus ostreatus and air drying has been suggested as a means of improving the protein digestibility of lentils and quinoa. SSF combined with air drying at 70 °C resulted in a slight increase in protein hydrolysis compared to unfermented samples. SSF was found to boost the proportion of small peptides to 35 %. Following digestion, SSF and drying yielded bioactive peptides of 1400 and 450 Da, with a range of 11 % to 28 %, respectively, and peptides < 190 Da making up 60 % of the total. SSF promoted valine, leucine, and isoleucine generation; however, hot air drying reduced free amino acids due to the amino acid-reducing sugar bonding but was never lower than the initial content of its unfermented counterpart. Furthermore, SSF and drying at 70 °C improved the release of hydrophobic amino acids (>70 mg/g dry basis) and negatively charged amino acids (>20 mg/g dry basis) in lentils during digestion. The SSF samples exhibited lower angiotensin converting enzyme (ACE) inhibitory activity, ≤35 %, compared to unfermented flours after digestion. However, the ACE inhibitory activity increased in SSF-dried samples, in part because of melanoidins generated during drying. Finally, lower values of protein digestibility and thus smaller peptides, amino acid profile, and ACE inhibitory activity of fermented flours were found in the older adult digestion model.

Solid-State Fermentation Improves Tobacco Leaves Quality via the Screened Bacillus subtilis of Simultaneously Degrading Starch and Protein Ability

The process of tobacco aging plays a significant role in enhancing the smoking experience by improving the flavor and quality of tobacco leaves. During natural aging, the metabolic activity of the microbes on the surface of tobacco leaves will be greatly changed. Besides, starch and protein are two of the main macromolecular compounds causing the poor smoking quality of tobacco leaves which to be degraded for better tobacco quality. In this study, a bacterium with the simultaneously degrading ability of starch (degradation rate of 33.87%) and protein (degradation rate of 20%) has been screened out from high-class tobacco leaf and then inoculated into low-class tobacco leaf by solid-state fermentation for quality improvement. The changes in components related to carbon and nitrogen showed that the strain had an obvious effect on the quality improvement of tobacco leaves. After that, GC-MS analyses displayed the volatile flavor compounds which become rich and the flavor has been improved. It has been proved that inoculation solid-state fermentation by dominant strain could improve tobacco quality, as well as instead of the traditional natural aging process which greatly shortens the aging process. The work also offers a helpful strategy for solid-state products for deep fermentation.

Study on the preparation process of quinoa anti-hypertensive peptide and its stability

Quinoa seeds are a food resource rich in protein, vitamins, minerals, and other functional components such as polyphenols, polysaccharides, and saponins. The seeds have become favored by modern consumers due to being gluten-free and featuring a high protein content. This study focused on the preparation of quinoa peptides by short-time enzymatic-assisted fermentation. Quinoa flour (QF) was mixed with water in a certain ratio before being enzymatically digested with 0.5% amylase and 0.1% lipase for 6 h. Then, 16 bacterial taxa were used for fermentation, respectively. The peptide content in the resulting fermentation broths were determined by the biuret method. The dominant taxon was then identified and the peptide content, amino acid distribution, and molecular weight distribution of the prepared quinoa peptides were analyzed. Further, the temperature, pH, metal ions, organic solvents, ion concentration, and anti-enzyme stability of the quinoa anti-hypertensive peptides of different molecular weights after fermentation with the dominant taxon were investigated. Finally, the inhibitory activity of fermented quinoa peptides on bacteria was studied. The results show that the peptide content of the fermentation broth reached 58.72 ± 1.3% at 40 h of fermentation with Lactobacillus paracasei and the molecular weights of the hydrolyzed quinoa peptides were mainly distributed below 2 kDa by polyacrylamide gel. The Angiotensin Converting Enzyme (ACE) inhibition and peptide retention of the 0-3 kDa quinoa peptides were screened to be high and stable. At the same time, the inhibitory activity of quinoa peptide after fermentation on E. coli was obvious. This study provides a theoretical basis for further research on quinoa peptide and its application in industrial production, and also lays a foundation for the later application of polypeptides in new food and chemical products.

Evaluating the Influence of Microbial Fermentation on the Nutritional Value of Soybean Meal

The aim of this article is to increase the nutritional value of soybean meal while reducing the content of antinutrients by microbial fermentation of soybean meal with a mixed culture of probiotic microorganisms (Bacillus subtilis, Aspergillus niger, Saccharomyces cerevisiae, Lactiplantibacillus plantarum) at two different hydromodules. The addition of microorganisms increased the content of easily digestible protein and amine nitrogen in fermented soybean meal (30:110 and 30:130, hydromodulus soybean meal:water) while decreasing urease activity (hydromodulus 30:110). The positive effect of microbial fermentation on the mineral composition of soybean meal was demonstrated. The ability of microorganisms in the fermentation process to increase the content of protein, essential amino acids, and macro- and microelements in soybean meal while decreasing anti-nutritional factors opens up possibilities for using this technology to advance animal husbandry.

Production, health-promoting properties and characterization of bioactive peptides from cereal and legume grains

The search for bioactive components for the development of functional foods and nutraceuticals has received tremendous attention. This is due to the increasing awareness of their therapeutic potentials, such as antioxidant, anti-inflammatory, antihypertensive, anti-cancer properties, etc. Food proteins, well known for their nutritional importance and their roles in growth and development, are also sources of peptide sequences with bioactive properties and physiological implications. Cereal and legume grains are important staples that are processed and consumed in various forms worldwide. However, they have received little attention compared to other foods. This review therefore is geared towards surveying the literature for an appraisal of research conducted on bioactive peptides in cereal and legume grains in order to identify what the knowledge gaps are. Studies on bioactive peptides from cereal and legume grains are still quite limited when compared to other food items and most of the research already carried out have been done without identifying the sequence of the bioactive peptides. However, the reports on the antioxidative, anticancer/inflammatory, antihypertensive, antidiabetic properties show there is much prospect of obtaining potent bioactive peptides from cereal and legume grains which could be utilized in the development of functional foods and nutraceuticals.

Effect of Steam Explosion on Structural Characteristics of β-Conglycinin and Morphology, Chemical Compositions of Soybean Meal

In this study, steam explosion was applied as a means to degrade β-conglycinin. We investigated changes in morphology, the chemical composition of soybean meal, and the structural characteristics of β-conglycinin. The results showed that steam explosion at 0.7 MPa for 8 min could effectively decrease the β-conglycinin content of soybean meal while the histamine content was not increased. The structural characteristics of soybean meal proteins were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), Fourier transform infrared spectroscopy (FTIR), circular dichroism (CD), and X-ray diffraction (XRD). Steam explosion caused the degradation of high weight proteins and reduced the band density of α', α, and β subunits in β-conglycinin. The micro-surface of soybean meal seemed to be in the cracked or puffed stage and the color became brown or dark after steam explosion. Steam explosion facilitated the dissolution of water-extractable arabinoxylans, which are 4.81 fold higher than that of native soybean meal. Phytic acid was exposed to the hydrothermal environment of the steam explosion process and consequently degraded by 12.95-24.69%. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of soybean meal extract was gradually increased from 20.70 to 33.71% with the rising of treated pressure from 0.3 to 0.7 MPa, which was 1.11-1.81 fold of native extract. The steam explosion may be a new modification technology that could decrease antigenicity, and steam-exploded soybean meal (0.7 MPa, 8 min) with lower β-conglycinin and phytic acid content that could be widely used in food products.

Microbial Population Succession and Community Diversity and Its Correlation with Fermentation Quality in Soybean Meal Treated with Enterococcus faecalis during Fermentation and Aerobic Exposure

This study assessed the effects of Enterococcus faecalis (E. faecalis) in combination with protease on fermentation characteristics and microbial communities during ensiling and aerobic exposure phases of soybean meal (SBM). In this study, response surface methodology (RSM) was used to optimize the optimal growth conditions of E. faecalis ZZUPF95, which produced protease, and fermented SBM under the optimal fermentation conditions. The fermentation test was divided into four groups as follows: CK (Control check), ZZUPF95, Protease and ZZUPF95+Protease groups. Results showed that the best medium ratio of ZZUPF95 was glucose 1%, peptone 2%, inorganic salt 1.47%; fermentation time 36 h, inoculation amount 10%, ratio of material to water 1:1 is the optimal fermentation scheme; after fermentation and aerobic exposure treatment, ZZUPF95 and ZZUPF95 + Protease group can reduce the pH of feed, improve the content of lactic acid in the fermentation system, and have the effect of inhibiting the reproduction of pathogenic bacteria, increasing the content of crude protein and ether extract, and degrading crude fiber; the microbial community of SBM were changed after fermentation and aerobic exposure. This study explored the changes of fermentation quality of SBM, which has certain theoretical value to improve the fermentation mode and storage of SBM.

Exploring the Impact of Solid-State Fermentation on Macronutrient Profile and Digestibility in Chia (Salvia hispanica) and Sesame (Sesamum Indicum) Seeds

Fermentation of plant-based substrates with edible fungi enhances the nutrient profile and digestibility, but it has been scarcely applied to edible seeds, which are rich in healthy lipids. In this study, chia and sesame seeds were solid-state fermented with Pleurotus ostreatus, followed by drying and milling. Fermentation led to increased content of lipid and protein in both seeds’ products, and a change in fatty acid profile in favor of increased polyunsaturated fatty acids. Then, the samples were subjected to in vitro digestion. Lipolysis, determined by nuclear magnetic resonance, was higher in sesame than in chia products, and the fermented counterparts had increased values compared to the controls. In terms of physical properties, fermentation showed reduced particle size and increased matrix degradation and decreased viscosity of the digestion medium, which were related to increased lipolysis. In conclusion, applying solid-state fermentation on chia and sesame seeds could be a recommendable approach.

Oilseed meals into foods: an approach for the valorization of oilseed by-products

The excellent health benefits of oil extracted from seeds have increased its application in foods, pharmaceutical and cosmetic industries. This trend leads to a growing research area on their by-products, oilseed meals, to minimize environmental and economic issues. Examples of these by-products are soybean, peanut, kenaf seed, hemp, sesame, and chia seed meals. It is well known that soybean meals have wide applications in food and non-food industries, while other seed meals are not well established. Most oilseed meals are rich in health beneficial compounds and are potential sources of plant protein, dietary fiber, and antioxidants. Many studies have reported on the valorization of these by-products into value-added food products such as bakery and meat products to increase their nutritional and functional properties. These efforts contribute to the sustainability, development of novel functional food and support the zero-waste concept for the environment. This review aims to provide information on the composition of selected oilseed meals from soybean, peanut, hemp, kenaf, sesame and chia seeds, their potential applications in the bakery, meat, beverage, pasta, and other food products, and to highlight the issues and challenges associated with the utilization of oilseed meals into various food products.

Optimization of Soybean Meal Fermentation for Aqua-Feed with Bacillus subtilis natto Using the Response Surface Methodology

This study aimed to improve the nutritional value of soybean meal (SBM) by solid-state fermentation (SSF) using Bacillus subtilis natto (B. s. natto) to overcome the limitations of SBM usage in aquafeed. The response surface methodology (RSM) was employed to explore the relationships of fermentation conditions, such as temperature, time, water-substrate ratio, and layer thickness, on the degree of protein hydrolysis (DH) and the crude protein (CP) content. The optimum conditions for achieving the higher DH (15.96%) and CP (55.76%) were 43.82 °C, 62.32 h, 1.08 of water-substrate ratio, and a layer thickness of 2.02 cm. CP and DH in the fermented soybean meal (FSM) increased by 9.8% and 177.1%, respectively, and crude fiber decreased by 14.1% compared to SBM. The protein dispersibility index (PDI) decreased by 29.8%, while KOH protein solubility (KPS) was significantly increased by 17.4%. Flavonoids and total phenolic acid content in FSM were increased by 231.0% and 309.4%, respectively. Neutral protease activity (NPA) also reached a high level (1723.6 U g−1). Total essential amino acids (EAA) in FSM increased by 12.2%, higher than the 10.8% increase of total non-essential amino acids (NEAA), while the total free amino acids content was 12.76 times higher than that of SBM. Major anti-nutritional factors in SBM were significantly reduced during the process, and almost all SBM protein macromolecules were decomposed. Together with the cost-effectiveness of SSF, B. s. natto-fermented SBM products have great potential to improve the plant composition and replace high-cost ingredients in aquafeed, contributing to food security and environmental sustainability.

Application of ultrasound technology in the field of solid-state fermentation: increasing peptide yield through ultrasound-treated bacterial strain

BACKGROUND

The increase of peptide yield contributed to reducing the usage of antibiotics in solid-state fermented feed. Ultrasound technology is used in the field of liquid-state fermentation to improve yield of fermented products but has not been utilized in the field of solid-state fermentation (SSF). The main objective of this study was to investigate the feasibility of improving peptide yield in SSF products through ultrasound-treated bacterial strain.

RESULTS

The highest peptides content in soybean meal SSF products reached 153.28 mg g-1 , which increased by 15.05% compared with the control. This content value was acquired through treating the bacteria of Bacillus amyloliquefaciens by ultrasound before inoculating into soybean meal under the optimized mode and parameters (simultaneous dual-frequency ultrasound mode, frequency combination of 40/60 kHz, total power density of 40 W L-1 , time of 20 min, pulse-on and pulse-off times of 40 and 60 s, delayed inoculation time of 0 h). Fermenting with ultrasound-treated bacterial strain can effectively increase peptide yield, biomass and protease activity of soybean meal fermented products during the SSF prophase. After treating by ultrasound, the latent phase and logarithmic phase of the bacterial strain shortened by 1 and 3 h while the generation time reduced by 23.64%. In qualitative test of protease activity, diameter ratio (DR) value of ultrasound-treated bacterial cells enlarged by 12.0% compared with the control.

CONCLUSION

Peptide yield of soybean meal SSF products can be improved through ultrasound-treated bacterial inoculum, which attributed to the promoting effect of ultrasound treatment on growth activity and protease production capability of bacterial cells. © 2021 Society of Chemical Industry.

Two-step biological approach for treatment of rapeseed meal

Rapeseed meal (RSM) is an important source of protein, but its value is limited due to the poor digestibility and the presence of many antinutritional factors. In this study, a two-step biological method was developed for detoxifying RSM and increasing its protein value. In the first stage, various detoxifying enzymes and proteases were produced by Aspergillus niger during solid-state fermentation (SSF). In the second stage, coordinated enzymatic hydrolysis was employed to further degrade the antinutritional factors and macromolecular proteins in the fermented RSM. Following fermentation at 30 °C for 48 hr and enzymatic hydrolysis at 45 °C for 24 hr, the content of trichloroacetic acid soluble protein (TCA-SP) and glucosinolates (GLS) in RSM was increased by 81.70% and reduced by 30.06%, respectively, compared with that obtained using the SSF process alone. Moreover, to improve the efficiency of enzymatic hydrolysis, the yield of acid protease was increased by optimizing the composition of the medium so that the TCA-SP content was increased to 208.39 mg/g and accounted for 51.62% of the total RSM protein, which was 99.36% and 629.66% higher than that in the fermented RSM and control, respectively. Overall, these results demonstrate that the two-step process could be more effective for the degradation of the antinutritional factors and improvement of the protein quality of RSM compared to use of the SSF method alone, which may improve the utilization of RSM in food and animal feed. PRACTICAL APPLICATION: Rapeseed meal (RSM) is a protein source that provides high-quality nutrition and can be applied to the development of value-added products for humans and animal feed. To improve the utilization of RSM, a combined method of solid-state fermentation and enzymatic digestion was developed. Compared with the traditional solid-state fermentation method, the present method further improves the quality of RSM and demonstrates improved efficacy in increasing the small peptide content while reducing the levels of antinutritional factors.

Enhancing the nutritional profile and digestibility of lentil flour by solid state fermentation with Pleurotus ostreatus

Lentils (Lens culinaris) present an excellent nutrient profile.

Separation, biochemical characterization and salt-tolerant mechanisms of alkaline protease from Aspergillus oryzae

BACKGROUND

The salt tolerance of proteases secreted by Aspergillus oryzae 3.042 closely relates to the utilization of raw materials and the quality of soy sauce. However, little is known about the salt-tolerant proteases and their salt-tolerant mechanisms.

RESULTS

In this study, we isolated and identified a salt-tolerant alkaline protease (AP, approximately 29 kDa) produced by A. oryzae 3.042. It was considered as a metal-ion-independent serine protease. The optimum and stable pH values were both pH 9.0 and the optimum temperature was 40 °C. Over 20% relative activity of AP remained in the presence of 3.0 mol L^-1 NaCl after 7 days, but its K_m and V_max were only mildly influenced by the presence of 3.0 mol L^-1 NaCl, indicating its outstanding salt tolerance. Furthermore, AP was more stable than non-salt-tolerant protease at high salinity. The salt-tolerant mechanisms of AP could be due to more salt bridges, higher proportion of ordered secondary structures and stronger hydrophobic amino acid residues in the interior.

CONCLUSIONS

The above results are vital for maintaining, activating and/or modulating the activity of AP in high-salt environments. They would also provide theoretical guidance for the modification of AP and the engineering of A. oryzae 3.042 so as to secrete more AP. © 2018 Society of Chemical Industry.