Soybean Protein Hydrolysates Research Articles

The role of duel hydrolysis of soybean on functional properties and protein digestibility: a sustainable approach.

Protein hydrolysates derived from food sources contains enormous number of peptides which are composed of amino acid possessess various bioactive properties. However, the use of protein hydrolysates as a nutraceutical is hindered due to their unpleasant flavour. The study aims to enhance the biological activity and palatability of protein hydrolysates. In the present study, soybean protein hydrolysate (SPH) was prepared using alcalase for 4 h (control). Modification of hydrolysis (MPH) was carried out by reiterating the hydrolysis of the supernatant obtained after 2 h of hydrolysis using an enzyme to 50% of alcalase during each successive hydrolysis. Samples were characterised by their physio-chemical and functional properties. Furthermore, the effect of modification on the protein digestibility and bitterness intensity using e-tongue was studied. The suppressive effect on retrogradation of corn starch was analysed using texture profile analysis. The results demonstrated increased protein content by 1.6 and 1.9% in MPH compared to SPH and UNH, respectively. MPH showed 1.5- and 1.6-fold higher DH% than SPH before and after gastrointestinal digestion (p < 0.05). A decrease in molecular weight was found in the order of UNH > SPH > MPH. Nevertheless, MPH displayed significantly higher functional properties (p ≤ 0.05). The hardness of retrograded corn starch was significantly reduced in the MPH (1.21N) than SPH (1.55 N) and UNH (1.81N) compared to control (1.71N) during 7-day storage at 4°C (p ≤ 0.05). E-tongue analysis of MPH showed a 4-fold reduction in bitterness than SPH. Modification of hydrolysis of soybean has demonstrated its significance in improved DH% functional properties and palatability. In addition, improved protein digestibility with promising benefits in deferral action on retrogradation of starch over the traditional process of hydrolysis was observed. The outcome of this study contributes to the potential utilisation of MPH as an ingredient in the formulation of nutraceutical products.

Bromelain Immobilized onto Clay-Carboxymethylcellulose Composites for Improving Nutritive Value of Soybean Meal.

Improvement of nutritional value and reduction of antinutritional factors (ANFs) of soybean meal (SBM) for animal feed applications could be achieved by using bromelain immobilized onto bentonite (Bt)-carboxymethylcellulose (CMC) composites. The composite with mass ratio between CMC to calcium ion (Ca2+) at 1:20 provided the highest enzyme activity, immobilization yield higher than 95%, with superior thermal and storage stabilities. Performance of the immobilized bromelain for soybean protein hydrolysis was further studied. The results showed that at 60 °C, the immobilized bromelain exhibited the highest efficiency in enzymatic hydrolysis to release free alpha amino nitrogen (FAN) as a product with high selectivity and to effectively reduce SBM allergenic proteins within 30 min. In conclusion, immobilization of bromelain onto Bt-CMC composites leads to stability enhancement of the enzyme, enabling effective improvement in SBM quality in a short treatment time and showing great potential for application in animal feed industries.

Purification, characterisation and visualisation of soybean protein hydrolysis by aspergillopepsin I from mangrove Aspergillus tubingensis

In order to obtain marine-derived enzymes suitable for protein hydrolysis in acid brewing system, seven species of fungi were obtained from mangrove soil. One of the strains, Aspergillus tubingensis, was determined to have a high acid protease production capacity. Its fermentation broth was purified and the obtained protease was identified as aspergillopepsin I (ATAP) with a molecular weight of 41205 Da. Homology modelling shows that ATAP contains three active sites, each containing to a Zn atom and amino acid residues. The enzyme had the highest relative activity at pH 3.5 and 35–40 °C, and exhibited pH and thermal stability at pH 3.0–3.5 and 20–50 °C. ATAP showed certain salt tolerance. K+ and Zn2+ promoted the enzyme activity, while Mg2+, Cu2+, Co2+, and Fe2+ slightly inhibited the enzyme activity. The results of inhibitors suggest that ATAP belongs to the class of aspartic proteases containing metal atoms. Furthermore, the results of enzymatic hydrolysis of defatted soybean powder showed that the contents of soluble protein, amino nitrogen, free amino acids and the proportion of small molecular peptides (<3 kDa) in the hydrolysate increased significantly. In addition, molecular docking of ATAP and aspergillopepsin I from Aspergillus oryzae 3.042 with soybean globulins (7S and 11S), respectively, showed better hydrolysis of soybean globulins by the former, especially for 7S globulin. Visual analysis indicated the interaction forces between enzymes and soybean globulins were dominated by hydrogen bond and hydrophobic interaction. In conclusion, ATAP may be a candidate as an enzyme preparation for the hydrolysis of soybean proteins.

Co-delivery of vitamin C and β-carotene in W/O/W emulsions stabilized by modified aggregated insoluble soybean protein hydrolysate-xanthan gum complexes

Environmentally friendly emulsifiers safe for human consumption are urgently needed to stabilize emulsions for applications in the food industry. In this study, we prepared complexes combining modified aggregated insoluble soybean protein hydrolysate (AISPH) mixed with xanthan gum (XG) (0.05–0.3 %, w/v), and further to construct water-in-oil-in-water (W/O/W) emulsions to deliver vitamin C and β-carotene. We observed a decrease in the AISPH α-helix and β-sheet content, surface hydrophobicity, and fluorescence intensity all decreased after binding. In contrast, the particle size and absolute ξ-potential significantly increased, indicating that molecular non-covalent interactions occurred in the solution. The emulsification property of AISPH was also improved by adding XG, and the AISPH-XG-stabilized emulsion showed improved stability, encapsulation efficiency, and rheological properties. Among them, AISPH-XG-0.25-stabilized emulsion exhibited a smaller particle size (8.41 ± 0.49 μm) and the highest encapsulation efficiency for vitamin C (90.03 ± 0.23 %) and β-carotene (70.56 ± 0.06 %). Additionally, simulated gastric digestion indicated that vitamin C and β-carotene bioavailability increased by 3.6 and 5.8 times, respectively. Finally, the emulsion exhibited good pH, ionic, and thermal stability. In general, AISPH-XG-stabilized W/O/W emulsions showed good stability and carrying capacity, providing a theoretical basis for improving their application.

Effects of Fermentation with Tetragenococcus halophilus and Zygosaccharomyces rouxii on the Volatile Profiles of Soybean Protein Hydrolysates.

The effects of fermentation with lactic acid bacteria (LAB) and yeast on the aroma of samples were analyzed in this work. The volatile features of different soybean hydrolysates were investigated using both GC-MS and GC-IMS. Only 47 volatile flavor compounds (VFCs) were detected when using GC-IMS, while a combination of GC-MS and GC-IMS resulted in the identification of 150 compounds. LAB-yeast fermentation could significantly increase the diversity and concentrations of VFCs (p < 0.05), including alcohols, acids, esters, and sulfurs, while reduce the contents of aldehydes and ketones. Hierarchical clustering and orthogonal partial least squares analyses confirmed the impact of fermentation on the VFCs of the hydrolysates. Seven compounds were identified as significant compounds distinguishing the aromas of different groups. The partial least squares regression analysis of the 25 key VFCs (ROAV > 1) and sensory results revealed that the treatment groups positively correlated with aromatic, caramel, sour, overall aroma, and most of the key VFCs. In summary, fermentation effectively reduced the fatty and bean-like flavors of soybean hydrolysates, enhancing the overall flavor quality, with sequential inoculation proving to be more effective than simultaneous inoculation. These findings provided a theoretical basis for improving and assessing the flavor of soybean protein hydrolysates.

Effect of fermentation with Tetragenococcus halophilus and Zygosaccharomyces rouxii on selected non-volatile taste compounds in soybean protein hydrolysates

This work was focused on investigating the effect of fermentation with Tetragenococcus halophilus and Zygosaccharomyces rouxii on the flavor characteristics of soy protein hydrolysates (SPH). The sensory attributes and non-volatile taste compounds of SPHs were analyzed using high performance liquid chromatography, electronic tongue and sensory evaluation. The results demonstrated that fermentation could effectively increase the contents of amino nitrogen, total acids, organic acids (especially lactic acid), umami amino acids (growth rate ranging from 10.9% to 30.6%) and sweet amino acids (increased by 7.8%–62.0%) compared with control groups, contributing to improve the acidity, as well as umaminess and sweetness taste of samples. Principal component analyses and partial least square discriminant analyses confirmed the substantial impacts on the non-volatile taste characteristics of SPHs by lactic acid bacteria (LAB) and yeast fermentation, especially for the flavor profile of the sample with Aspergillus oryzae hydrolysis and sequential addition of LAB and yeast (SFH-2), and the sample with commercial protease hydrolysis and simultaneous addition of LAB and yeast (SH-1). These findings provided a theoretical basis for enhancing the flavor intensity of soybean protein hydrolysates.

Peptides isolated from black soybean synergistically inhibit the activity of angiotensin converting enzyme (ACE)

The main purpose of this study was to isolate and identify Angiotensin Converting Enzyme (ACE) inhibitory peptides (IPs) from black soybean protein hydrolysate and compare the activity between single and mixed peptides. Black soybean protein was hydrolyzed, desalted, and separated by size-exclusion ultrafiltration and G-15 Sephadex column. A total of 31 peptides were identified by nano-HPLC-ESI-MS/MS. 7 peptides were screened by molecular docking, only three were ACEIPs after synthetized and bioactive verified, namely KDFPPR (IC50 = 7.91 ± 0.27 mg/mL), VVPPGHPF (IC50 = 12.13 ± 0.38 mg/mL) and DTFPYPR (IC50 = 10.69 ± 0.28 mg/mL), 3 peptides all show mixed-type mode of enzyme inhibition. The synergistic effect on the inhibition of ACE activity was shown among the three ACEIPs. The other four peptides play an auxiliary role in the activity of three ACEIPs mixtures. This study showed that black soybean protein is a reliable source of ACEIPs and the synergism of natural mixed peptides may play an important role in the activity of bioactive peptides.

Bitter Peptides in Fermented Soybean Foods - A Review.

Fermented soybean foods with a long history are popular worldwide because of rich nutrition. However, many traditional fermented soybean foods have unacceptable bitterness, which mostly comes from the bitter peptides produced from the hydrolysis of soybean proteins. In this review, the bitter peptides in fermented soybean foods is briefly reviewed. The structural properties of bitter receptors and bitter peptides were reviewed. Bitterness is perceived through the binding between bitter compounds and specific sites of bitter receptors (25 hTAS2Rs), which further activate the downstream signal pathway mediated by G-protein. And it converts chemical signals into electrical signals, and transmit them to the brain. In addition, the influencing factors of bitter peptides in fermented soybean foods were summarized. The bitterness of fermented soybean foods primarily results from the raw materials, microbial metabolism during fermentation, unique techniques, and interactions of various flavor compounds. Moreover, the structure-bitterness relationship of bitter peptides was also discussed in this review. The bitterness degree of the bitter peptide is related to the polypeptide hydrophobicity, amino acids in the peptide, peptide molecular weight and polypeptide spatial structure. Studying the bitter peptides and their bitter characteristics in fermented soybean foods is beneficial for improving the sensory quality of fermented soybean foods and prompting more consumers accept them.

Germinated soybean protein hydrolysate: a possible chemopreventive agent

This work aimed to explore the chemopreventive effect of six days germinated soybean protein hydrolysate (PH) in a murine model. Germinated soybean protein isolate was obtained by isoelectric precipitation, then it was hydrolysate with pepsin and pancreatin. The amount of protein in PH was 62% with a hydrolysis degree of 68%. For the in vivo test, ICR male mice with an average weight of 25 g were used, distributed in 4 groups with 12 animals in each: the negative control was administered only with a saline solution via intraperitoneal (IP); the positive control was administered 4 times with azoxymethane (AOM) via IP (7.5 mg/kg); group PH100 (PH 100 mg/kg) given orally daily plus AOM given 4 times IP (7.5 mg/kg) and PH400 (PH 400 mg/kg) given orally daily plus AOM given 4 times IP route (7.5 mg/kg). The positive control presented decreased body weight gain, high disease activity index (DAI), and colon with intestinal mucosal damage, compared to the other three groups. The oral administration of PH (PH100 and PH400) in mice decreased body weight loss and reduced the DAI score, being the high dose (PH400) the one that presented the best protective activity. Therefore, it is necessary to continue studying the in vivo effects of germinated soy protein hydrolysate and develop foods that take advantage of its positive effects on health.

Legume - an inconspicuous fighter against the metabolic syndrome

Metabolic syndrome (MetS) is metabolic alterations characterised by dysglycemia, raised blood pressure, elevated triglyceride levels, low high-density lipoprotein cholesterol levels, and obesity. It is associated with high morbidity and mortality and the prevalence of it has been increasing in recent years. A significant impact on the risk to develop MetS has dietary habits. Many studies emphasise legume consumption advantages contributing to a decrease of a cluster of metabolic risk factors. The most effective range daily legume consumption is between 55 and 70 g/day. Some varieties of legumes can reform blood pressure by ACE inhibitory activity. Soybean protein hydrolysis showed an advantageous effect on lipid profile by HMGCR inhibitory activity. Legume intake seems to be a valuable predictor of decreasing BMI and abdominal adiposity because of high fibre levels and regulation of adiponectin and 8-epi-PGF2α in obese subjects. Increasing part of legumes as a protein and carbohydrates source in diet, significantly reduces the risk of glucose-insulin homeostasis disorders. Evidently, legumes have comprehensive dietary advantages. However more data and further research on the long-term effects of legumes on metabolic alterations are required to elucidate their effective health implications. Present review is based on articles accessible on pubmed service.

Multi-dimensional analysis of heat-induced soybean protein hydrolysate gels subjected to ultrasound-assisted pH pretreatment

This study aimed to evaluate the gelation characteristics of soybean protein hydrolysate (SPH) extracted by enzyme-assisted aqueous extraction. Specifically, the changes in gelation behaviors for heat-induced (95 °C, 20 min) SPH dispersions treated with pH (pH 3, 5, 9; pH 7 as control) and ultrasound (U; 240 W, 30 min) were investigated. The results showed that typical gel behavior with high elastic nature in the viscoelasticity and network structures were observed during the heating process, where the disulfide bond played a dominant role in the gel network formation of all the samples. Notably, the heat-induced aggregation in the SPH gels was mainly formed by the association of the basic B polypeptide in 11S and β subunit in 7S. The most superior SPH gel was formed at pH 7 when assisted by ultrasonication during the heating process. This as-synthesized gel showed a uniform filamentous structure and exhibited the more excellent textural, rheological and thermal properties than those of the samples formed under acidic and alkaline conditions. These results are of great value in revealing the gelation mechanism of SPH.

Effects of Fish Meal Replacement with Composite Mixture of Soybean Protein Hydrolysates and Other Plant Proteins on Growth Performance, Antioxidant Capacity, and Target of Rapamycin Pathway in Largemouth Bass

AbstractA feeding trial was conducted to evaluate the effect of fish meal replacement with a composite mixture of soybean protein hydrolysates and other plant proteins on growth performance, antioxidant capacity, and target of rapamycin pathway in Largemouth Bass Micropterus salmoides. Triplicate groups of Largemouth Bass were fed the diet formulated with 40% (FM40; control), 35% (FM35), 30% (FM30), or 25% (FM25) fish meal for 10 weeks. The results revealed that the best growth performance was achieved in the FM35 group, while a negative effect on growth was observed in the FM25 group. The feed intake of the FM30 and FM25 groups was significantly lower than the other two groups, while no significant difference was observed in feed efficiency ratio and protein efficiency ratio. No statistical difference was observed in the activity of serum alanine transaminase and aspartate transaminase with the replacement of fish meal. However, the replacement of fish meal with composite plant protein significantly reduced hepatic malondialdehyde content, and a significant improvement in total antioxidant capacity was observed in the FM35 group. Gene expression analysis revealed that the expression of amino acid transporter LAT1 was significantly elevated in the FM35 group, while no significant difference was observed in the LAT2 expression among different treatments. No significant difference was observed in the expression of target of rapamycin among treatments. However, the expression of ribosomal protein S6 in the FM35 and FM30 groups was significantly higher than in the other two groups, while the replacement of fish meal significantly decreased the expression of eukaryotic initiation factor 4EBP1. In summary, the composite mixture of soybean protein hydrolysates and other plant proteins can reduce the use of fish meal from 40% to 35%.

Structural properties and antioxidant activities of soybean protein hydrolysates produced by Lactobacillus delbrueckii subsp. bulgaricus cell envelope proteinase

In this work, we investigated the structural and biological properties of soybean protein isolate (SPI) after 0–8 h hydrolyzation with cell envelope proteinase (CEP) extracted from Lactobacillus delbrueckii subsp. bulgaricus. CEP hydrolysis increased the β-sheet and red-shifted the fluorescence peak, while decreasing the α-helix, indicating the unfolding of soybean proteins. Increased surface hydrophobicity and fluorescence of the soybean protein hydrolysates were correlated with the increased hydrophobic amino acid (from 209.67 to 217.6 mg/100 g). CEP tended to hydrolyze the N- and C-terminal regions of sequences dominated by Gly and Leu, which enhanced the antioxidant activity of the SPHs (lowest IC50s value of ABTS•+ and hydroxyl radical scavenging activity were 0.324 ± 0.006 mg/mL and 0.365 ± 0.001 mg/mL after 4 h hydrolysis). Comparison with the database of bioactive peptides suggested various potential biological activities, including antioxidant activity, angiotensin-converting enzyme inhibitory activity and dipeptidyl peptidase-IV inhibitory activity. The study findings have theoretical significance for the development of CEP hydrolysis and novel bioactive soybean peptides.

Эффективность применения фитаз и ударно-дезинтеграторно-активаторной обработки сои для снижения фитиновой кислоты в гидролизатах соевого белка

The efficiency of phytase and impact-disintegrator-activator processing (IDAP) of soybean in obtaining protein hydrolysate from full-fat soybean flour to reduce phytic acid in the hydrolysate was shown. For the experiments, samples of full-fat soybean flour were used, obtained through soybean processing using two different methods: impact disintegration-activation processing (IDAP) and a grinder with a rotor-knife working element (RKP – rotor-knife processing). The IDAP of soybeans was conducted using a DEZI-11 disintegrator unit with six-row rotors rotating at a frequency of 210 s-1. The RKP was carried out using a Gamlux GL-CG mill with a rotor rotation frequency of 20500 rpm. Enzymatic treatment of the mixture of full-fat soybean flour and water (with a water-to-material ratio of 1:6) was performed using the enzyme preparation Phytaflow (with an activity of 20000 U/cm3), with different dosages of phytase added: 20; 40; 60, and 80 U/g of full-fat soybean flour. The enzymatic treatment was conducted at a temperature of 50°C for a duration of 120 minutes. As a result of the studies, it was found that the design of the working body of the chopper affects the degree of soybean degradation, the content of phytic acid in full-fat soybean meal, and the efficiency of phytase action in obtaining protein hydrolysate. The content of phytic acid in full-fat soybean meal obtained after processing on the impact-disintegrator-activator type unit is 12% lower than in full-fat soybean meal obtained after processing on the grinder with a rotary knife working body. Phytase was found to decrease the phytic acid content in protein hydrolysate obtained after processing soybeans with the impact-disintegrator-activator unit more effectively than in protein hydrolysate obtained after processing soybeans with the shredder with the rotary knife-type working body. The hypothesis of the effect of IDAP soybean on the efficiency of phytic acid reduction and enzymatic phytase hydrolysis was confirmed and showed a high degree of significance. The reduction of phytic acid in full-fat soybean meal and protein hydrolysates obtained from it is of great practical importance as it allows to create functional foods with high digestibility and protein bioavailability and to increase the doses of inclusion of full-fat soybean meal in starter feeds of animals, birds, and aquaculture.

Selenium-enriched peptides identified from selenium-enriched soybean protein hydrolysate: protective effects against heat damage in Caco-2 cells.

Our previous study evaluated the antioxidant and anti-inflammatory activities of selenium-enriched soybean peptides (SePPs) in vivo. In this study, we purified SePPs via gel filtration chromatography and obtained five fractions (F1, F2, F3, F4 and F5), among which F3 displayed the highest antioxidant and anti-inflammatory activities. Nineteen selenium-enriched peptides were identified in F3 by mass spectrometry. Two selenium-enriched peptides with sequences ESeCQIQKL (Sep-1) and SELRSPKSeC (Sep-2) were selected for synthesis based on their score and the number of hydrophobic amino acids, acidic and basic amino acids. Both Sep-1 and Sep-2 exhibited preventive effects on the heat stress-induced impairment of intestinal epithelial cell integrity, oxidative stress and inflammatory responses in a Caco-2 cell model. Pretreatment of the cells with Sep-1 or Sep-2 for 24 h reduced intracellular reactive oxygen species (ROS) generation, prevented the disruption of tight junction (TJ) proteins, and decreased paracellular permeability. Western blot results showed that Sep-1 and Sep-2 could improve the abnormal expressions of Nrf2, Keap1, NLRP3, caspase-1 and ASC/TMS1, thereby enhancing the glutathione (GSH) redox system and reducing IL-1β and IL-18 concentrations. Sep-1 activated the Nrf2-Keap1 signaling pathway significantly more than Sep-2. Molecular docking results indicated that Sep-1 and Sep-2 are both bound to Keap1 and NLRP3 in the form of hydrogen bonds, hydrophobic interactions and salt bridges, which interferes with Nrf2 and NLRP3 signaling. Molecular dynamics simulations suggested that more hydrogen bonds were formed during the resultant process of Sep-1 with Keap1, and the compactness and stability of the complex structure were better than those of Sep-2. These findings confirm the value of both Sep-1 and Sep-2 in the development of dietary supplements as potential alternatives for heat damage and related disease prevention.

Effects of high-pressure homogenization on physicochemical and functional properties of enzymatic hydrolyzed soybean protein concentrate.

This paper investigates the effect on the physicochemical and functional properties of soybean protein concentrate (SPC) by using Alcalase protease and high-pressure homogenization (HPH) (0, 20, 40, 60, 80, and 100 MPa) for the combined modification. The results showed that the degree of hydrolysis of SPC was 4.1% and the antigen protein was degraded after Alcalase hydrolysis, when the homogenization pressure (HP) was 6 0Mpa, the particle size of the SPC was the smallest, the zate potential absolute value up to 33.45 mV, the secondary structure has the lowest β-sheet content, the highest random coil content, and the highest surface hydrophobicity (H0), the size of protein fragments on the microstructure surface is the smallest, the lowest denaturation temperature (T d ) and enthalpy (△H) are 72.59°C and 1.35 J/g, the highest solubility is 80.54%, and the highest water and oil holding capacities are 7.73 g/g and 6.51 g/g, respectively. The best emulsifying activity and emulsifying stability were 43.46 m2/g and 190.35 min, the most even distribution of emulsion droplets. This indicates that the HPH treatment destroys the structure of enzymatic hydrolyzed SPC, changes its physicochemical properties, and improves its functional properties. In this study, SPC was modified by HPH and enzyme combined treatment, in order to improve the functionality and application range of SPC, and provide a theoretical basis for its high-value utilization in the food field.

Characterization of proteases from Irpex lacteus grown on minimally denatured soybean meal.

Acid and thermal stabilities are important properties for the preparation of acidic protein beverage. It is an important method for enzymatic modification to improve the functional properties of protein. Irpex lacteus protease showed a selective hydrolysis to soy proteins. The purpose of this study was to investigate the mechanism of enzymatic hydrolysis and its effects on acid and thermal stabilities of soy proteins. The I.lacteus protease selectively hydrolyzed the α and α' subunits of the native soybean β-conglycinin (7S globulin) to produce products that presented as the 55 kDa band upon sodium dodecyl sulfate polyacrylamide gel electrophoresis. The amino acid sequences of 55 kDa polypeptides were analyzed in gel multi-enzyme digestion followed by liquid chromatography-mass spectrometry. By matching the multi-enzyme digestion peptides with the published polypeptide chain sequences of the α and α' subunits, it was confirmed that the 55 kDa polypeptides were formed by eliminating amino acid residues on both sides of the N- and C-terminals. From the published protein structure database (https://www.uniprot.org/), it is known that the cleaved peptide bonds were in extension regions. Non-selective enzyme hydrolysis of both β-conglycinin (7S globulin) and glycinin (11S globulin), with corresponding drastic increases in the degree of hydrolysis, was observed when the substrates were preheated to the denaturation degree of 40% and above. However, 55 kDa hydrolyzed products and B polypeptides showed some extent of resistance to the proteolysis by I.lacteus protease even if denaturation degree was 100%. Both selective and non-selective hydrolysis of soy proteins by I.lacteus protease improved the acid and heat stabilities under the same hydrolysis conditions (enzyme/substrate ratio, time, and temperature). Enzymatic hydrolysis of soybean proteins by the I.lacteus protease can effectively improve the acid and thermal stabilities of proteins. This discovery is significant to avoid aggregation during processing in the beverage industry. In the near future, the protease has potential application value for modification of other proteins. © 2022 Society of Chemical Industry.

Physicochemical Antioxidative and Emulsifying Properties of Soybean Protein Hydrolysates Obtained with Dissimilar Hybrid Nanoflowers.

This study investigated the changes in the structure and properties of soybean protein after hydrolysis using two types of hybrid nanoflowers (alcalase@Cu3(PO4)2•3H2O (ACHNs) and dispase@Cu3(PO4)2•3H2O (DCHNs)) and examined the basic properties and oxidative stability of hydrolyzed soybean protein emulsions. The formations of the two hybrid nanoflowers were first determined using a scanning electron microscope, transmission electron microscope, and Fourier infrared spectroscopy. The structure and functional properties of soybean protein treated with hybrid nanoflowers were then characterized. The results indicated that the degree of hydrolysis (DH) of the ACHNs hydrolysates was higher than that of the DCHNs for an identical reaction time. Soybean protein hydrolysates treated with two hybrid nanoflowers showed different fluorescence and circular dichroism spectra. The solubility of the hydrolysates was significantly higher (p &lt; 0.05) than that of the soybean protein (SPI) at all pH values tested (2.0-10.0)*: at the same pH value, the maximum solubility of ACHNs hydrolysates and DCHNs hydrolysates was increased by 46.2% and 42.2%, respectively. In addition, the ACHNs hydrolysates showed the highest antioxidant activity (DPPH IC50 = 0.553 ± 0.009 mg/mL, ABTS IC50 = 0.219 ± 0.019 mg/mL, and Fe2+ chelating activity IC50 = 40.947 ± 3.685 μg/mL). The emulsifying activity index of ACHNs and DCHNs hydrolysates reached its maximum after hydrolysis for 120 min at 61.38 ± 0.025 m2/g and 54.73 ± 0.75 m2/g, respectively. It was concluded that the two hydrolysates have better solubility and antioxidant properties, which provides a theoretical basis for SPI product development. More importantly, the basic properties and oxidative stability of the soybean-protein-hydrolysates oil-in-water emulsions were improved. These results show the importance of proteins hydrolyzed by hybrid nanoflowers as emulsifiers and antioxidants in the food and pharmaceutical industry.

Variation of moisture state and taste characteristics during vacuum drying of Maillard reaction intermediates of hydrolyzed soybean protein and characterization of browning precursors via fluorescence spectroscopy

Maillard reaction intermediates (MRIs) derived from enzymatic hydrolysates of soybean protein were prepared by combining dehydration method with spray drying and vacuum drying. Taste characteristics, browning precursors, water activity, and moisture state were monitored during the process of vacuum drying. The water activity was significantly reduced and the proportion of bound water was increased, which could promote the large accumulation of MRIs. The saltiness, umami, and bitterness responses of MRIs were all reduced and the reduction of taste intensity during vacuum drying was probably caused by the reaction of small peptides of taste-active amino acids with glucose. The continuous accumulation of browning precursors during vacuum drying was confirmed by fluorescence spectroscopic analysis and by quantitative analysis of α-dicarbonyl compounds. Subsequent browning reactions further demonstrated that the MRI with the highest fluorescence intensity also had the greatest browning potential.

Influence of the Degree of Hydrolysis on Functional Properties and Antioxidant Activity of Enzymatic Soybean Protein Hydrolysates.

Soybean protein hydrolysates were prepared using two proteolytic enzymes (Alcalase and Protamex) and the degree of hydrolysis (DH) and their functional and antioxidant properties were evaluated. The highest DH value was 20%, with a yield of 19.77% and protein content of 51.64%. The total amino acid content was more than 41% for all protein hydrolysates. The protein hydrolysates from Protamex at pH 2.0 had excellent solubility, emulsifying activity, and foaming capacity, at 83.83%, 95.03 m2/g, and 93.84%, respectively. The water-holding capacity was 4.52 g/g for Alcalase, and the oil-holding capacity was 4.91 g/g for Protamex. The antioxidant activity (62.07%), as measured by the samples’ reaction with DPPH (2,2-diphenyl-1-picrylhydrazyl) and the reducing power (0.27) were the strongest for Protamex. An ABTS activity rate of 70.21% was recorded for Alcalase. These findings indicated a strong potential for the utilization of soybean protein hydrolysates to improve the functional properties and antioxidant activity of soybeans as well as their nutritional values.