Soybean Protein Hydrolysates Research Articles

Antioxidant activity of SSeCAHK in HepG2 cells: a selenopeptide identified from selenium-enriched soybean protein hydrolysates.

This paper is aimed at purifying and identifying selenium (Se)-containing antioxidative peptides from Se-enriched soybean peptides (SSP). In this work, the SSP was separated into five fractions (F1 to F5). Fraction F4, displaying the highest antioxidative activity, was further separated, and sub-fractions F4-1 to F4-5 were selected for antioxidative activity evaluation using 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2-azino-bis-(3-ethylbenzo-thiazoline-6-sulphonic acid)diammonium salt (ABTS), and OH− radical scavenging assays. The Se-containing antioxidative peptides with sequence Ser–SeC–Ala–His–Lys (SSeCAHK) were identified in sub-fraction F4-1 and chemically synthesized. This Se-containing pentapeptide showed a preventive effect against hydrogen peroxide (H2O2)-induced oxidative stress in HepG2 cells. Pretreating the cells for 2 h with SSeCAHK (0.13–0.50 mg mL−1) induced strong intracellular, reactive oxygen species (ROS) scavenging activity while preventing a decrease in reduced glutathione (GSH) and an increase in malondialdehyde (MDA). Therefore, SSeCAHK treatment improved H2O2-induced oxidative stress in HepG2 cells, demonstrating the significant potential of SSeCAHK as a natural antioxidative functional material for dietary supplementation.

Comparison of alcalase- and pepsin-treated oilseed protein hydrolysates – Experimental validation of predicted antioxidant, antihypertensive and antidiabetic properties

There is emerging evidence on the importance of food-derived bioactive peptides to promote human health. Compared with animal derived proteins, plant proteins, in particular oilseed proteins, are considered as affordable and sustainable sources of bioactive peptides. Based on our previous bioinformatic analysis, five oilseed proteins (flaxseed, rapeseed, sunflower, sesame and soybean) were enzymatically hydrolysed using alcalase and pepsin (pH 1.3 and pH 2.1). Further, low molecular weight (Mw ​< ​3 ​kDa) fractions were generated using ultrafiltration. The protein hydrolysates and their low Mw fractions were evaluated for their in vitro antioxidant, antihypertensive and antidiabetic capabilities, in comparison with samples obtained from two dairy proteins (whey and casein). Apart from dipeptidyl-peptidase IV inhibition, significantly stronger bioactivities were detected for the low Mw fractions. In partial agreement with in silico predictions, most oilseed hydrolysates exerted comparable angiotensin-converting enzyme inhibitory capability to dairy proteins, whilst whey protein was the most promising source of dipeptidyl-peptidase IV inhibitors. Apart from alcalase-treated soybean, dairy proteins were more efficient in releasing antioxidant peptides as compared to oilseed proteins. On the other hand, soybean protein hydrolysates showed the highest α-glucosidase inhibitory activity amongst all protein sources. Overall, there was limited correlation between in silico predictions and in vitro experimental results. Nevertheless, our results indicate that oilseed proteins have potential as bioactive peptide sources, and they might therefore be suitable replacers for dairy proteins as well as good sources for development of functional foods.

Optimizing of Enzyme Hydrolysis Condition for Bitterness Suppression of Soybean Protein Using Response Surface Methodology (RSM)

Enzyme hydrolysis of soybean protein can be adjusted according to purposes, but should be optimized for reaction time, concentration and substrate conditions to prevent bitterness caused by excessive hydrolysis. This study was carried out to find the optimal condition of the soybean protein hydrolysis process using a response surface methodology. The experiment was designed based on a central composite design, and the independent variables were the soybean protein extraction pH (X1, 10-12), enzyme concentration (X2, 0.1-0.5%) and hydrolysis time (X3, 150-210 minutes). The results of the degree of hydrolysis (Y1), pH (Y2) and soluble solid contents (Y3) were fitted to a response surface methodology model (R2= 0.91, 0.98, and 0.86, respectively). The optimal hydrolysis condition for soybean protein hydrolysis was as follows; pH 12, enzyme concentration 0.27% and 187.88 min, respectively. While richness and sourness were increased with soybean protein hydrolysis, the saltiness was decreased. The bitterness of the hydrolysate prepared at the optimal condition did not show any difference compared with that of the soybean protein, whereas richness and sourness showed a significant increase. The enzyme hydrolysate at the optimal condition showed distribution of a molecular weight lower than the soybean protein did to form intense bands at 35, and 25 kDa. Therefore, this hydrolysate was expected to be used as a high-value plant protein food material.

Effects of different dietary levels of soybean protein hydrolysates on the growth performance, antioxidant capacity and relative mRNA expression levels of juvenile hybrid grouper ( Epinephelus fuscoguttatus ♀ × Epinephelus lanceolatus ♂)

An 8‐week feeding trial was conducted to investigate the effect of different dietary levels of soybean protein hydrolysates (SPH) on the growth performance, antioxidant capacity, non‐specific immunity and mRNA expression levels of insulin‐like growth factor I (IGF‐I), target of rapamycin (TOR) and oligopeptide transporter 1 (PepT1) for juvenile hybrid grouper (average weight: 12.5 ± 0.40 g). Five iso‐protein and iso‐lipid diets were formulated by adding 0, 10, 20, 40 and 60 g/kg of SPH, respectively. The SPH2‐6 significantly reduced feed conversion ratio and enhanced weight gain rate, specific growth rate and protein efficiency ratio (p < .05). The treatment groups significantly decreased the total protein (p < .05). The cholesterol, low‐density lipoprotein and high‐density lipoprotein of fish fed with SPH6 were significantly lower (p < .05) than control. Fish fed with SPH4 and SPH6 had significantly higher catalase, superoxide dismutase and alkaline phosphatase activities, as well as significantly lower malondialdehyde than the control (p < .05). The levels of aspartate aminotransferase, alanine transaminase, lysozyme, lipase, trypsin, pepsin, complement 3 and complement 4 showed a similar trend of initially increasing and then decreasing. The SPH2‐6 significantly increased IGF‐I and TOR mRNA expressions in liver as well as PepT1 in intestine (p < .05). The optimal SPH inclusion level was estimated to be 42.99 g/kg diet for juvenile hybrid grouper.

A novel aminopeptidase with potential debittering properties in casein and soybean protein hydrolysates.

A new aminopeptidase (An-APa) was identified and biochemically characterized from Aspergillus niger CICIM F0215. It had maximal activity at 40°C and pH 7.0 and exhibited a broad substrate specificity both on hydrophilic and hydrophobic amino acid residues at N-terminals. With An-APa hydrolysis for 1h, the casein-pepsin and soybean protein isolates (SPI)-pepsin hydrolysates released both hydrophilic and hydrophobic amino acids and the hydrophobic amino acids having Q values (degree of hydrophobicity) greater than 1500cal/mol were remarkably released. Leu, Ile, Phe, Tyr, Trp, Pro, Val and Lys in the casein hydrolysate after treatment with An-APa increased 18.61, 0.84, 11.35, 13.18, 3.34, 6.30, 7.46, and 8.19mg/100mL, respectively, and 19.72, 1.47, 18.37, 11.72, 4.61, 4.10, 8.13, and 5.85mg/100mL, respectively, in the SPI hydrolysate. Both accounted for 65.0% and 64.4% of total released free amino acids from casein and SPI hydrolysates, respectively. This indicated that An-APa could be potentially applicable in debittering protein hydrolysates.

An innovative two-step enzyme-assisted aqueous extraction for the production of reduced bitterness soybean protein hydrolysates with high nutritional value

Soybean protein hydrolysates (SPH), by-product of enzyme-assisted aqueous extraction (EAEP), were a promising source of natural nutraceutical. Nevertheless, the bitterness of SPH has limited their use as food ingredients or additives. The objectives of the present study were to use two-step enzyme-assisted aqueous extraction to produce SPH with reduced bitterness and high nutritional value (antioxidant activity and peptide nitrogen levels). In this study, the optimum conditions for SPH production were obtained using Protex 6L (2 h) followed by Protease A 2SD (3 h) in two-step hydrolysis. The bitterness of SPH was positively correlated with the hydrophobic amino acids (Ala, Leu, Ile, Trp, Phe, Tyr) and hydrophobic peptide fractions. Additionally, the produced potential bitter peptides of SPH-6L were identified and predicted by LC-MS/MS and bioinformatics. IceLogo plot and heat map revealed that Protease A 2SD tends to cleave Leu and Arg residues from the N-terminal in bitter peptide to degrade bitter peptide. Thus, it could be concluded that the utilization of multi-enzyme hydrolysis, could be a promising process for the production of SPH with low bitter and potential antioxidant activity, which offers a promising approach for enhancing the usability and high-valued utilization of EAEP.

The Effect of Ascorbic Acid and Soybean Protein Hyrolysate to Iron Binding Capacity

The study aimed to investigate the effect of ascorbic acid and soybean protein hydrolysate to iron-binding capacity. BPPT (Agency for the Assessment and Application of Technology) developed soybean hydrolysate, which was obtained by thermal and enzymatic hydrolysis. Ascorbic acid was added in sample preparation with composition 0, 50, 75 and 100%. Soybean protein hydrolysate (SPH) was prepared by gel filtration chromatography using Sephadex G-25 to separate peptide based on molecular weight. Characterization of SPH and SPH fractions was also conducted, such as protein concentration, molecular weight, iron-binding capacity, and amino acid concentration. Iron binding capacity was determined by the colorimetric method using an ortho-phenanthroline reagent. The result showed that soybean protein hydrolysate increases iron-binding capacity 25-37 times than ascorbic acid. Arginine, aspartic acid, glutamic acid, threonine, lysine, and serine were found as amino acids responsible for iron-binding capacity in the SPH.

Influence of Single/Collective Use of Curing Agents on the Curing Behavior and Bond Strength of Soy Protein-Melamine-Urea-Formaldehyde (SMUF) Resin for Plywood Assembly.

Soybean protein hydrolysate, melamine, urea, and concentrated formaldehyde were used to synthesize an environmentally friendly soybean protein-melamine-urea-formaldehyde (SMUF) co-condensation resin. (NH4)2SO4, (NH4)2HPO4, (NH4)2HPO4 + (NH4)2SO4, (NH4)2HPO4 + (NH4)2S2O8, and (NH4)2HPO4 + (NH4)2SO4 + (NH4)2S2O8 were employed as curing agents for SMUF resin. The curing and thermal behaviors of the SMUF resin were investigated using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The results revealed the following: (1) (NH4)2SO4 alone could not cure the SMUF resin completely; thus, the final shear strength accomplished plywood with the resin was low, and its water resistance was poor, while the adhesive section was loose and porous/brittle after curing. (2) (NH4)2HPO4 could be hydrolyzed to generate H+ and promote SMUF curing, but it could also form polyphosphoric acids, resulting in crosslinking reactions with SMUF in parallel; thereby, the curing properties were improved. (3) When (NH4)2HPO4 + (NH4)2SO4 + (NH4)2S2O8 were engaged collectively as curing agent, the shear strength, water resistance, and heat resistance of SMUF attained were the best possible whereas the curing temperature was decreased and the heat released by curing was elevated substantially, which signifies maximized extent of crosslinking was achieved. Further, the adhesive section exhibited mostly a crosslinking intertexture as demonstrated by means of SEM. Accordingly, this study may serve as a guide for the curing of amino resins, with low-molar ratio of formaldehyde to amine in adhesives, which are applied to plywood production.

Synergistic effects of plant protein hydrolysates and xanthan gum on the short- and long-term retrogradation of rice starch

Controlling and delaying the retrogradation of gelatinized rice starch (GRS) can improve the quality of GRS-based foods during storage. Here, we evaluated the influence of corn protein hydrolysates (CPHs), rice protein hydrolysates (RPHs), wheat protein hydrolysates (WPHs), and soybean protein hydrolysates (SPHs) on inhibiting the short- and long- term retrogradation of RS-xanthan gum mixtures. Compared with WPHs, RPHs, CPHs, the SPHs cooperating with xanthan gum (SPHs-XT) showed the highest inhibitory effect. The increased loss tangent (tan δ) in the dynamic viscoelastic measurement suggested that SPHs-XT enhanced the liquid-like properties of GRS gel. The decreased storage modulus (G') and the reduced setback value indicated that the short-term retrogradation of GRS was restrained by SPHs-XT. Meanwhile, during a 14-day storage at 4 °C, the hardness of GRS gel was significantly decreased from 1382.5 g to 201.4 g after the addition of SPHs-XT before storage determined by using a texture profile analysis (TPA), and the relative crystallinity of the retrograded GRS was decreased from 18.18% to 8.15% determined by using a X-ray diffraction (XRD) with a corresponding decrease of the retrogradation enthalpy determined by using a differential scanning calorimetry (DSC). These results suggested that SPHs-XT could inhibit the the long-term retrogradation of GRS. Moreover, the water molecules were determined to be locked in GRS gel after the addition of SPHs-XT by using a low-field nuclear magnetic resonance (LF-NMR). In addition, thin membranes and filaments formed by the addition of SPHs-XT in GRS gel were observed by using a scanning electron microscopy (SEM), suggesting a decreased cross-linking of GRS molecules by the addition of SPHs-XT to form ordered structures. These results indicated that the addition of SPHs-XT is a potential to inhibit the short- and long-term retrogradation of GRS and further to improve the nutrition of the GRS based products.

Nanotechnology for enhancing the production of meat-like flavour from enzymatic hydrolyzed soybean protein isolate.

Enzymatic hydrolyzed vegetable proteins have been recommended as safe precursors of pro- cess flavours. However, the degree of hydrolysis limits their production on an industrial scale. Nanotechnology can enhance the enzymatic hydrolysis of soybean protein. Therefore, the aim of the present study was to use the enzymatic hydrolyzed soybean protein isolate (E-SPI) nanoparticles for producing a high yield of meat-like process flavour. Ball milling, high-speed homogenization and ultra-sonication were used for prepa- ration of SPI nanoparticles with average range 10&ndash;17 nm. The volatile compounds were analyzed by head- space solid phase microextraction (HS-SPME) and gas chromatography coupled with mass spectrometry (GC-MS). The odour attributes of beefy, roasty, savoury, sulphurous and overall acceptability were selected to describe the meat-like process aroma. The total volatiles in the headspace of the meat-like process flavour based on SPI nanoparticles showed a higher yield compared with the untreated sample. Thiols containing compounds, especially the potent odorants of meat-like flavour, were predominant in both samples. However, their yield was significantly higher in the SPI nanoparticles sample. An agreement was found between the intensity of the attributes selected and the aroma composition of the two meat-like flavours investigated. The results of this study suggest that using protein nanoparticles as the main precursors of the process flavours is considered a new chance for innovation in nanoscience. Future studies will be carried out on improving the quality and quantity of vegetable protein nanoparticles that can be used as precursors of another process flavours.

Nanotechnology for enhancing the production of meat-like flavour from enzymatic hydrolyzed soybean protein isolate [pdf

Nanotechnology for enhancing the production of meat-like flavour from enzymatic hydrolyzed soybean protein isolate [pdf

Identification and characterization of multifunctional cationic peptides from enzymatic hydrolysates of soybean proteins

In this study, we used the commercial soybean protein hydrolysate Hinute-DC6 as a novel starting material from which to purify and identify multifunctional cationic peptides. After fractionation, Hinute-DC6 was separated into 20 fractions with varying isoelectric points (pI) by ampholyte-free isoelectric focusing (autofocusing). Subsequently, we purified and identified the cationic peptides from fractions 19 and 20, which had pI values greater than 12, using reversed-phase high-performance liquid chromatography and matrix-assisted laser/desorption ionization-time-of-flight mass spectrometry. Of the 83 cationic peptides identified, 14 had high pI values and net charges greater than+2, and were chemically synthesized and assayed for various bioactivities, including hemolytic, antimicrobial, lipopolysaccharide (LPS)-neutralizing, and angiogenic activities. None of the 14 cationic peptides tested exhibited hemolytic activity toward mammalian red blood cells at concentrations up to 1000μM. Five of the cationic peptides exhibited antimicrobial activities against at least one of four human-pathogenic microorganisms tested. In addition, in chromogenic LPS-neutralizing assays using Limulus amebocyte lysates, the 50% effective concentrations of these 14 peptides were between 0.069 and 5.2μM. Tube-formation assays in human umbilical vein endothelial cells showed that each of the 14 cationic peptides exhibited significant angiogenic activities at 10μM, with values similar to those of the positive control LL-37. Our results demonstrate that the 14 identified cationic peptides have multiple functions with negligible hemolytic activity. These data indicate that the cationic peptides isolated from Hinute-DC6 and fractions containing these cationic peptides have the potential to be used as multifunctional ingredients for healthcare applications.

Study on lipids transfer in aqueous enzyme hydrolysis soybean protein and oil extraction process

Enzyme-assisted aqueous Extraction of soybean oil is a promising green and safe alternative to traditional process. However, it is quite difficult to realize industrial application as the process needs large dosage of special enzyme and high-speed separation. To overcome these problems, the quantitative transfer of oil release during the hydrolysis of soybean protein by protease was studied. The results showed that the 1398 neutral protease with the total amount of only 720 IU/g soybean could be used to hydrolyze the soy protein, and the oil yield reached up to 90% after separation by the centrifugal force of 1960 × g. The enzymatic hydrolysis of soybean protein was beneficial to release and separate oil from soybean, and the separated protein could enrich almost 99.0% of oil from hydrolyzed emulsion. At the moment, the emulsification could be eliminated during the process of aqueous extraction with petroleum ether.

Soybean Trypsin Inhibitors: Selective Inactivation at Hydrolysis of Soybean Proteins by Some Enzymatic Complexes

Inactivation of the Kunitz and Bowman-Birk soybean trypsin inhibitors at hydrolysis of soybean proteins by enzymatic complexes was studied. These complexes are derived from king crab hepatopancreas, cod fish pyloric caeca, and a commercial enzymatic complex of protosubtilin. Analysis of the soybean protein hydrolysates showed that these enzymatic complexes completely digested the Kunitz trypsin inhibitor (60–70% of the total trypsin inhibitors) and had almost no effect on the Bowman-Birk trypsin and chymotrypsin inhibitor. All of the enzymatic complexes contain different sets of enzymes with different proteolytic specificity. This allow to make the conclusion that Bowman-Birk inhibitor is highly resistant to proteolysis and is not inactivated at enzymatic hydrolysis.

Hydrolysates of Soybean Proteins for Starter Feeds of Aquaculture: The Behavior of Proteins upon Fermentolysis and the Compositional Analysis of Hydrolysates

Currently, soybean occupies the first place as a global protein source for replacing fish meal in animal and aquaculture feeds. Since at the stage of fish postembryonic development, before the switch to active feeding, the efficacy of proteolysis in larvae is not high enough, soybean proteins in starter feeds should be hydrolyzed. The hydrolysate composition and behavior of the resulting protein fragments were shown to differ when soybean proteins were hydrolyzed by different enzyme preparations: the enzyme complex from the hepatopancreas of the Kamchatka crab (EC HPKC), protosubtilin, and the enzyme complex from pyloric appendage of cod (EC PAC). The most active enzyme preparation among them was EC HPKC, which demonstrated a high proteolytic activity at room temperature. Upon hydrolysis by EC HPKC, the yield of soluble hydrolysis products was 92% per weight of the initial protein material. Depending on the incubation time, the hydrolysates contained up to 60% of free amino acids (per weight of the hydrolyzed protein mixture) and short peptides less than 3 kDa. The use of protosubtilin or EC PAC at room temperature resulted in the intensive gelation and coagulation of the formed protein fragments resistant to further degradation. In order to achieve the yield of soluble hydrolysis products comparable with that for EC HPKC, it was necessary to increase the temperature. The yield of soluble products upon the EC PAC-induced hydrolysis of soybean proteins at 37°C achieved 82–88% of the initial protein material. The greatest part of the hydrolysate was represented by low-molecular-weight peptides with a molecular weight lower than 10 kDa and free amino acids (20.16% of the weight of the hydrolyzed protein mixture). Although the optimal temperature for the protosubtilin activity is 40–60°C according to the manufacturer’s data we did not perform hydrolysis in the presence of protosubtilin at this temperature because of the hazard to sulfur-containing amino acids. The content of free amino acids and the size of protein fragments in the soybean protein hydrolysates obtained upon the EC HPKC-induced hydrolysis at room temperature and with EC PAC at 37°C met the requirements for the fish starter feeds. Manipulations with such parameters as the hydrolysis time and the enzyme complex/protein ratio for the used enzyme preparations allow to prepare soybean protein hydrolysates differing in their hydrolysis degree.

Facile synthesis of alcalase-inorganic hybrid nanoflowers used for soy protein isolate hydrolysis to improve its functional properties

In this work, a facile approach was developed to synthesized alcalase-inorganic hybrid nanocomposite (alcalase@CaHPO4) by immobilizing alcalase with calcium hydrogen phosphate (CaHPO4). The nanocomposite possessed flower-like morphological features with excellent hydrolysis activity on soybean protein isolates (SPI) with 1.57 fold higher compared to free alcalase. The experiment was evident of alcalase@CaHPO4 hybrid nanoflowers with 90% sustainability after the seven cycles of reusability and 80–100% relative activity at 50–70 °C and with 65% at pH 4 in acidic condition. Soybean protein hydrolysates (SPHs) produced by immobilized alcalase possessed 70% radical-scavenging capacity at 0.8 mg/mL concentration and 20% calcium-binding capacity at pH 6. The solubility of SPHs produced by alcalase@CaHPO4 hybrid nanoflowers was also improved by 15% compared to free alcalase. The high radical scavenging capability, good calcium binding capacity and improved solubility of SPHs prepared through alcalase@CaHPO4 hybrid nanoflowers would be highly promising in food industries.

Multifunctional peptides for the prevention of cardiovascular disease: A new concept in the area of bioactive food-derived peptides

Abstract Bioactive peptides derived from food proteins are increasingly recognized as useful tools for improving health. In this dynamic field, multifunctional peptides represent an emerging area: this definition indicates those peptides which have the capacity to impart more than one physiological outcome by affecting different targets. They may be considered an improvement in respect to monofunctional peptides, owing to lower negative side effects and reduced costs. This review discusses the current information on multifunctional peptides useful in the area of cardiovascular disease prevention. Hypocholesterolemic/anti-diabetic peptides were identified in soybean and lupin protein hydrolysates, whereas hypotensive/anti-diabetic peptides in milk proteins hydrolysate. Antioxidant peptides with at least another biological activity (hypotensive peptides, anti-diabetic and hypocholesterolemic) were purified from hempseed, lentils, rice bran, milk, egg yolk, and cumin protein hydrolysates. The polypeptide lunasin is hypocholesterolemic, antioxidant, and anti-inflammatory. Finally, the current hurdles in view of their practical exploitation are discussed in detail.

Soybean protein hydrolysate-formaldehyde-urea block copolymer for controlled release fertilizer

ABSTRACTUrea formaldehyde (UF) was modified by the soybean protein hydrolysate (SPH) to adjust the rate of nitrogen, phosphorus, and potassium (NPK) release. The SPH section can copolymerize into the UF molecules. The crystallinity of modified UF fertilizer decreased with increasing SPH content. The surface of SPH-modified UF fertilizer was loose and porous. The nitrogen content of SPH-modified UF fertilizer decreased a little, but the nitrogen, phosphorus and potassium release rate was improved with increasing SPH content in modified fertilizer. The grain number per ear, thousand-grain weight and total yield were improved by the SPH-modified UF fertilizer. Compared to UF and control, protein, starch, fat, soluble sugar and vitamin C in the maize were increased by applying SPH-modified UF fertilizer. The results indicated that the nutrient release behavior can be adjusted by the introduced SPH to match the maize needs.

Biodegradable copolymer-based composites made from straw fiber for biocomposite flowerpots application

Biodegradable copolymer-based composites produced from straw fiber (SF) with hydrolyzed soybean protein isolate/urea/formaldehyde (HSPI/U/F) copolymer-based adhesive for biocomposite flowerpots (BFP) application was presented in this work, and molecular structure, morphology, biodegradability and microbial population of the resulting materials were also investigated. FTIR and SEM results indicated that the copolymer resin have been successfully prepared. The prepared BFP showed good biodegradation, and the introduction of HSPI increased the degradation rate of BFP, which was nearly 50% at 24 months. After 30 days of controlled composting, the CO2 release accumulation of BFP could reach 24 g. During the process of BFP degradation, the number of bacteria and fungi on the surface was higher than that of actinomyces, indicating the bacteria and fungi selectively accumulated on the BFP composites surface to accelerate its degradation. At the same time, nitrate ion could also be formed by nitrobacteria, which promoted plant growth. There is no doubt that the obtained biodegradable copolymer possessed great potential for BFP application.

Effect of Partial Hydrolysis with Papain on the Characteristics of Transglutaminase-Crosslinked Tofu Gel.

The effects of partial enzymatic hydrolysis of soymilk on the characteristics of transglutaminase (TG)-crosslinked tofu gel were studied. SDS-PAGE showed that the molecular weight of the partially hydrolyzed soybean protein was reduced to that of a digested peptide (less than 43.0kDa) when papain was added at more than 50μL/100mL soymilk. The content of free sulfhydryls, β-sheets, and random coils in papain-treated soymilk increased. When TG was added to soy milk after papain treatment and tofu gel was formed, its storage modulus increased from 957.44 to 1241.39Pa. The gel strength, water-holding capacity, and nonfreezing water content of the tofu gel were greater than those without enzyme treatment. Scanning electron microscopy revealed that limited papain hydrolysis stimulated TG-catalyzed cross-linking of soymilk to form a dense gel network structure, whereas an extended enzymatic hydrolysis of soymilk did not promote crosslinking by TG. PRACTICAL APPLICATION: This work investigated the effect of partial hydrolysis on TG cross-linked tofu gel. Partial hydrolysis of soybean protein with papain can promote TG cross-linking reaction, thus form a dense network structure, increase gel strength, and water-holding capacity. Therefore, it can be used to produce a good gel product with higher gel strength, springiness, water-holding capacity, and a more dense microstructure.