Neutrase Hydrolysate Research Articles

Preparation and identification of novel DPP-IV inhibitory peptides from Musculus senhousei: Peptidomic analysis, molecular simulation, and validation

Bioactive peptides have been considered effective alternatives for the treatment of type 2 diabetes targeting the dipeptidyl peptidase-IV (DPP-IV). In this study, novel DPP-IV inhibitory peptides were prepared and identified from Musculus senhousei through two-stage chromatographic purification, peptidomic analysis, in silico screening, and validation. Furthermore, molecular simulation was employed to analyze the interaction from a molecular perspective. Results showed that Musculus senhousei hydrolysate produced by 8 h Neutrase hydrolysis exhibited the significant DPP-IV inhibitory activity. Purification and identification led to the discovery of 387 peptide sequences. A total of 11 novel peptides with potential DPP-IV inhibitory activity were screened in silico. Further synthesis and validation of peptide activity showed that LTWR and DPF significantly inhibit DPP-IV in a competitive inhibitory manner, with IC50 values of 1788.67 ± 28.13 and 1399.73 ± 27.15 μM, respectively. Results from molecular docking and dynamic simulations indicated that peptides LTWR and DPF could tightly bind to the catalytic site of DPP-IV through hydrogen-bond and hydrophobic interaction. These findings suggested that Musculus senhousei could serve as a natural source of bioactive peptides for potential treatment of type 2 diabetes.

Valorization of protein from by-product of purified rice starch industry: Protein hydrolysates exhibit a potential heat resistance and protease inhibition besides foam formation and stability properties

This study aimed to enhance the added value of protein from by-products of the purified starch industry (BPSI). Proteins from BPSI were extracted with 0–660 UI α-amylase before being hydrolyzed by neutrase from 0 to 175 UI for 0–150 min at 80 °C, pH 5.3. The results showed that with 264 UI of α-amylase treatment for 60 min, the extraction of proteins improved the content of protein recovery up to 87.1%. The kinetic parameters of neutrase were Vmax = 0.8982 μMol tyrosine/min and Km = 0.9103%. The most effective condition for neutrase hydrolysis was 150 UI, 120 min, and 20% protein concentration. The highest hydrolysis efficiency reached 16%. The recovered protein has few free amino acids compared with those in the hydrolysates. The protein hydrolysate (PH) showed high foam forming and stabilizing properties for 30 min compared with those of the natural protein recovered. Furthermore, the PH exhibited heat resistance and protease inhibition properties. Thus, the purity and natural state of PH extracted by α-amylase could be improved. Foam formation and stabilization together with heat resistance and proteinase K inhibition exhibited by the PH indicate the potential application of this in the rice beer industry.

Identification of Novel Dipeptidyl Peptidase-IV Inhibitory Peptides in Chickpea Protein Hydrolysates.

Dipeptidyl peptidase-IV (DPP-IV) is one of the main targets for blood sugar control. Some food protein-derived peptides are thought to have DPP-IV inhibitory (DPP-IVi) activity. In this study, chickpea protein hydrolysates (CPHs) obtained through Neutrase hydrolysis for 60 min (CPHs-Pro-60) exhibited the highest DPP-IVi activity. DPP-IVi activity after simulated in vitro gastrointestinal digestion was maintained at >60%. Peptide libraries are established after the identification of peptide sequences. Molecular docking verified that the four screened peptides (AAWPGHPEF, LAFP, IAIPPGIPYW, and PPGIPYW) could bind to the active center of DPP-IV. Notably, IAIPPGIPYW exhibited the most potent DPP-IVi activity (half maximal inhibitory concentration (IC50): 12.43 μM). Both IAIPPGIPYW and PPGIPYW exhibited excellent DPP-IVi activity in Caco-2 cells. These results indicated that chickpea could be used as a source of natural hypoglycemic peptides for food and nutritional applications.

Produksi Hidrolisat Protein Kacang Koro Benguk dengan Aktivitas Penghambat Kerja Enzim Pengkonversi Angiotensin melalui Kombinasi Fermentasi dan Hidrolisis Enzimatik

Mucuna bean (Mucuna pruriens L.) is a legume having high protein content which has the potential as a source of bioactive peptides. One of the bioactive peptides is an angiotensin-converting enzyme (ACE) inhibitor, thus, mucuna beans might be used as a potential source of antihypertensive compounds. This study aimed to increase the functionality of proteins from mucuna beans as ACE inhibitors using a combination of fermentation and enzymatic hydrolysis followed by membrane filtration. The mucuna beans were fermented for 0, 24, 48, 96, and 144 h. The highest ACE inhibitory activity of 54.37%, was obtained by fermentation of the beans at 48 h, with a protein content of 20.82 mg/mL. The 48 h fermented mucuna beans were further hydrolyzed using alcalase or neutrase and subsequently filtered with UF membranes having 20,10 and 5 kDa cut-off. The enzymatic hydrolysis followed by membrane filtration increased the ACE inhibitory activity of mucuna beans. The neutrase hydrolysates resulting from 5 kDa membrane filtration showed the best ACE inhibitory activity (62.96% with a protein content of 10.39 mg/mL). A combination of fermentation and enzymatic hydrolysis followed by filtration using UF-membrane was able to produce ACE inhibitory peptides from mucuna beans. The potential of mucuna beans peptides as ACE inhibitors was due to the presence of negatively charged amino acid residues such as Asp and Glu, positively charged amino acids such as Arg and Lys, and hydrophobic amino acids such as Val, Leu, Ala, and Ile.

Integrated Evaluation of Dual-Functional DPP-IV and ACE Inhibitory Effects of Peptides Derived from Sericin Hydrolysis and Their Stabilities during In Vitro-Simulated Gastrointestinal and Plasmin Digestions.

Sericin, a byproduct of the silk industry, is an underutilized protein derived from the yellow silk cocoon. This research aimed to produce and characterize the bioactive peptides from sericin using various enzymatic hydrolysis methods. Alcalase, papain, neutrase, and protease were tested under their respective digestion conditions. Among the enzymes tested, neutrase-catalyzed sericin into specific peptides with the strongest dipeptidyl peptidase IV (DPP-IV) and angiotensin-converting enzyme (ACE) inhibitory properties. The peptides were subjected to a simulated in vitro gastrointestinal (GI) digestion in order to determine their stability. The GI peptides that were produced by neutrase hydrolysis continued to have the highest DPP-IV and ACE inhibitory activities. The neutrase -digested peptides were then fractionated via ultrafiltration; the peptide fraction with a molecular weight <3 kDa (UF3) inhibited DPP-IV and ACE activities. After being subjected to in vitro blood plasma hydrolysis, the UF3 was slightly degraded but retained its bioactivity. As a result of these findings, sericin peptides can be utilized as novel dietary ingredients that may alleviate some metabolic syndromes via the dual inhibitory properties of DPP-IV and ACE.

Gelatins and antioxidant peptides from Skipjack tuna (Katsuwonus pelamis) skins: Purification, characterization, and cytoprotection on ultraviolet-A injured human skin fibroblasts

For full use of Skipjack tuna (Katsuwonus pelamis) canning by-products, gelatins (STG) were extracted from tuna skins using acid (STG-A), enzyme (STG-E) and hot water (STG-H) methods with yields of 65.30 ± 1.56%, 39.83 ± 1.61%, and 50.97 ± 1.44%, respectively. Due to the high imino acid contents (228, 216, and 213 residues/1000 residues for STG-A, STG-E, and STG-H, respectively), STG-A showed the highest transparency and gel strength properties. Amino acid analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), ultraviolet (UV) and Fourier transform infrared spectroscopy (FTIR) analysis confirmed that STG-A, STG-E, and STG-H kept the main structure of type I collagen, but enzyme and hot water extraction methods showed much stronger hydrolysis ability on α and β chains. Moreover, neutrase hydrolysate (STG-AH) of STG-A showed the highest 1,1-diphenyl-2-picrylhydrazyl radical (DPPH•) scavenging activity and the fraction STG-AH-І (<3.5 kDa) from STG-AH prepared by ultrafiltration could significantly protect human skin fibroblasts (HSFBs) against ultraviolet-A (UVA) injury. Furthermore, nineteen peptides with high antioxidant activity were purified from STG-AH-І and identified. These results suggested that STG-AH and its derived antioxidant peptides could serve as potential ingredients applied in health benefiting products for preventing UVA injury.

Structure and activity of bioactive peptides produced from soybean proteins by enzymatic hydrolysis

Peptides are good food stabilizers and thickeners. They also present good bioactivities. The structure characteristics of peptides are related to the health benefits. In this study, immunoregulatory peptides were produced by Alcalase® and neutrase hydrolysis of soybean proteins. UHPLC-MS/MS was applied for structure identification. The immumoregulatory activities and mechanisms were investigated. Eighty five peptides were identified from the hydrolysates and 84 peptides might be immunoregulatory peptides. Most of them were novel immunoregulatory peptides. These peptides had good immunoregulatory activities, including increasing the pinocytotic capacity, and inducing the production and genes expression of NO, IL-6 and TNF-α in a dose-dependent manner. Specific inhibitors of NF-κB and JNK could significantly suppress NO production stimulated by soybean peptides, implying that NF-κB and JNK pathways were involved in their immunoregulatory mechanisms. Our results suggested that the soybean peptides prepared in this study were promising immunomodulatory neutraceuticals.

Using RSM for Optimum of Optimum Production of Peptides from Edible Bird's Nest By-Product and Characterization of Its Antioxidant's Properties.

In this research, the neutrase hydrolysis conditions of edible bird’s nest (EBN) by-products were optimized by response surface methodology (RSM). Antioxidant peptides were then isolated from the EBN by-products by ultrafiltration and chromatography taking the DPPH radical scavenging ability as an indicator. The antioxidant activity of the purified peptides was estimated by radical scavenging ability and sodium nitroprusside (SNP)-induced damage model in PC12 cells. When the enzyme concentration was10 kU/g-hydrolysis temperature was 45 °C, and hydrolysis time was 10.30 h, the degree of hydrolysis (DH) of EBN by-product hydrolysate (EBNH) was the highest. The purified peptide exerted strong scavenging ability with EC50 values of 0.51, 1.31, and 0.65 mg/mL for DDPH, ABTS, and O2− radicals, respectively. In addition, the purified peptides could significantly reduce the SNP-induced oxidative damage of PC12 cells, and twelve peptides that were rich in leucine (Leu), valine (Val), and lysine (Lys) were identified by LC-MS/MS. These results suggested that EBN by-products have potential as new materials for natural antioxidant peptides.

Optimization of fish oil extraction from Lophius litulon liver and fatty acid composition analysis

The Lophius litulon liver was used as raw material for the extraction of fish oil via various extraction methods. The extraction rate by water extraction, potassium hydroxide (KOH) hydrolysis and protease hydrolysis were compared and the results revealed the protease hydrolysis extraction had a higher extraction rate with good protein-lipid separation as observed by opticalmicroscope.Furthermore, subsequent experiments determined neutrase to be the best hydrolytic enzyme in terms of extraction rate and cost. The extraction conditions of neutrase hydrolysis were optimized by single-factor experiment and response surface analysis, and the optimal extraction rate was 58.40 ± 0.25% with the following conditions: enzyme concentration 2,000 IU/g, extraction time 1.0 h, liquid-solid ratio 1.95:1, extraction temperature 40.5°C and pH 6.5. The fatty acids composition in fish oil from optimized extraction condition was composed of 19.75% saturated fatty acids and 80.25% unsaturated fatty acids. The content of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) were 8.06% and 1.19%, respectively, with the ratio (6.77:1) surpassed to the recommendation in current researches (5:1). The results in this study suggest protease treatment is an efficient method for high-quality fish oil extraction from Lophius litulon liver with a satisfactory ratio of DHA and EPA.

Antioxidant peptides from protein hydrolysate of skipjack tuna milt: Purification, identification, and cytoprotection on H2O2 damaged human umbilical vein endothelial cells

To make full use of tuna by-products to prepare high-value products, skipjack tuna (Katsuwonus pelamis) milt was degreased, pretreated with microwave and separately hydrolyzed using trypsin, Neutrase, papain, and pepsin. Neutrase hydrolysate with the highest degree of hydrolysis (29.54 ± 1.19 %) and antioxidant activities were separated by ultrafiltration and a series of chromatographic methods, and thirteen antioxidant oligopeptides were prepared and identified as GHHAAA, PHPR, AKHQ, GRVPRV, ADMYW, VDDDD, SVTEV, VKIYI, VRDQY, IRDDY, YREY, AQRPR, and SMDV with molecular weights of 562.6, 505.6, 482.7, 654.8, 685.1, 578.0, 534.2, 634.6, 679.2, 681.2, 630.0, 626.4, and 450.0 Da, respectively. Moreover, GHHAAA, PHPR, SVTEV, VRDQY, and SMDV showed the highest Ferric-reducing power and radical scavenging activity on DPPH (EC50 values of 1.09 ± 0.08, 1.19 ± 0.07, 0.89 ± 0.08, 0.88 ± 0.11, and 1.24 ± 0.09 mg/mL, respectively) and ABTS (EC50 values of 1.12 ± 0.06, 1.14 ± 0.11, 1.02 ± 0.07, 1.04 ± 0.12, and 1.16 ± 0.07 mg/mL, respectively). In addition, GHHAAA, PHPR, SVTEV, VRDQY, and SMDV presented significant protective function on H2O2 oxidative damaged HUVECs by increasing the HUVECs viability and antioxidant enzyme activity, and lower the contents of ROS and MDA. This study suggested that GHHAAA, PHPR, SVTEV, VRDQY, and SMDV could be natural antioxidant ingredients used in pharmaceutical and functional products.

A Skate Skin Hydrolysate Restores Cognitive Function in 5XFAD Alzheimer Disease Mice Model by Suppressing Amyloid-β Accumulation via Upregulation of ERK-CREB

Alzheimer’s disease is a neurodegenerative disease hallmarked by gradual loss of neurons. The prevalence of such degenerative neuro-diseases has increased with an increase in the life expectancy especially as seen in developed countries. Amyloid-β (Aβ) is a chief intermediary for synaptic dysfunction and cognitive injury associated with Alzheimer's disease. However, the exact mechanism of the toxic effect of Aβ is still not entirely understood. Presently there is no known treatment for Alzheimer's disease. In this study, the effect of the long-term administration of SSH (skate skin neutrase hydrolysate) on Aβ associated cognitive impairment in an Alzheimer's disease mouse model (5XFAD mouse) was investigated. Investigation on cognitive function was measured using two behavioral tasks i.e. the Y-maze task and the Morris water maze task. The long term administration of SSH to 5XFAD mouse showed a marked behavioral improvement. 5XFAD mice that were treated with SSH showed minimal accumulation of Aβ. This implies SSH’s ability to prevent the accumulation of Aβ. In the group, the reduced activation of ERK-CREB (extracellular signal-regulated kinase-cAMP response element binding protein) was rescued by the treatment with SSH. It can be deduced that the activation of ERK-CREB is a major pathway through which SSH improves cognitive deficits observed in Alzheimer's disease.

Physicochemical properties and antioxidant activities of tree peony (Paeonia suffruticosa Andr.) seed protein hydrolysates obtained with different proteases

The physicochemical and antioxidant properties of tree peony seed protein (TPSP) hydrolysates by Alcalase, Neutrase, Papain, Protamex, and Flavourzyme were investigated in this study. The physicochemical properties were characterized by SDS-PAGE, particle size distribution, fourier transform infrared and fluorescence spectroscopy etc. The antioxidant activities were determined by DPPH radical, ABTS radical, Fe2+ chelating, and reducing power. The results showed five proteases produced hydrolysates with a significantly reduced average particle size, α-helices, and surface hydrophobicity compared to TPSP. Alcalase and Neutrase hydrolysis enhanced the nutritional value of the hydrolysates. Alcalase hydrolysates possessed the highest degree of hydrolysis (27.97%) and lowest molecular weight (<13 kDa) with average particle size (231.33 nm). Alcalase hydrolysate displayed the highest radical scavenging (DPPH IC50 = 0.18 mg/mL, ABTS IC50 = 1.57 mg/mL), Fe2+ chelating activity (IC50 = 0.99 mg/mL), and reducing power (0.594). These results provide the fundamentals for TPSP hydrolysates as antioxidants to be employed in food industry or pharmaceutical industry.

Physicochemical and gelling properties of whey protein hydrolysates generated at 5 and 50 °C using Alcalase® and Neutrase®, effect of total solids and incubation time

Gelation temperature (Tg), apparent viscosity (ηapp), turbidity and chromatography profiles of whey protein concentrate (WPC) and corresponding hydrolysates (WPHs) generated with Alcalase® and Neutrase® at different temperatures and total solids (TS) were compared. WPC incubated with Alcalase at 50 °C exhibited the highest rate and degree of hydrolysis (DH). After 4 h, the 5 °C Alcalase WPH (10% TS) had a DH and molecular mass distribution similar to those generated at 5 and 50 °C with Neutrase; however, the chromatography profiles differed. Tg was lower for WPHs than for WPC and depended on both the enzyme and TS. Moreover, the Tgs were lower for the Alcalase hydrolysates than for those generated with Neutrase. The ηapp and turbidity properties of the hydrolysates depended on the enzyme used, solution TS and incubation temperature. Hydrolysates had lower ηapp than WPC. The 50 °C Neutrase hydrolysates displayed lower turbidity than the corresponding Alcalase hydrolysates.

Identification of novel anti-inflammatory peptides from bee pollen (Apis mellifera) hydrolysate in lipopolysaccharide-stimulated RAW264.7 macrophages

Bee pollen protein was hydrolyzed using the commercial Alcalase, Flavourzyme and Neutrase enzymes. The Neutrase hydrolysate formed from a 1:1 (v/v) enzyme/substrate ratio (NH1) showed the highest nitric oxide (NO) radical scavenging activity. The NH1 was further separated into five fractions based on molecular weight (MW1–5) and MW1, the smallest weight fraction (< 0.65 kDa), possessed the highest NO inhibitory activity. The effects of NH1 on the production of NO were assessed by incubating with lipopolysaccharide-stimulated RAW264.7 macrophage cells. NO levels from the culture supernatants were determined by the Griess reaction. The results showed that MW1 suppressed the production of pro-inflammatory cytokines including cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), tumor interleukin-6 (IL-6) and necrosis factor transcript expression (TNF-α) in RAW264.7 macrophage cells. Thus, the MW1 fraction was fractionated using reversed-phase high-performance liquid chromatography into six principal fractions (H1–6), where H2, H3 and H4 showed strong NO inhibitory activity. Seven peptide sequences were obtained by quadrupole time-of-flight mass spectrometry, three of which displayed potent anti-inflammatory activity and may be useful ingredients in functional food and pharmaceutical drugs.

Antioxidant Characteristics and Identification of Peptides from Sorghum Kafirin Hydrolysates.

Grain sorghum is gaining interest for various uses as a highly sustainable crop. Kafirin is the main storage protein in grain sorghum. However, the antioxidant activities of kafirin hydrolysates have not been systematically investigated. The objectives of this study were to characterize the antioxidative hydrolysates and their ultrafiltrated fractions from sorghum kafirin using chemical assays and model systems and to identify the representative peptides. Kafirin Neutrase hydrolysates displayed promising yield and antioxidant capacity among those prepared with several different proteases. The effects of critical variables including protein substrate content, enzyme-to-substrate ratio, and reaction time on antioxidant production were studied. Selected hydrolysates were further fractionated through ultrafiltration and gel filtration chromatography (GFC). Medium-sized fraction (3 to 10 kDa) revealed relatively higher total phenolic content and stronger antioxidative activities with regard to free radical scavenging activity, metal ion chelating activity, reducing power, and oxygen radical absorbance capacity. In an oil-in-water emulsion system, incorporation of selected fraction of hydrolysates inhibited the formation of primary and secondary oxidation products by 83.03% and 65.59%, respectively, by the end of a 14-day incubation period. Similar oxidation inhibition effect was also observed in a ground meat system. Peptide compositions of the most promising fraction from GFC and reversed-phase high-performance liquid chromatography were identified using matrix-assisted laser desorption ionization-time of flight/time of flight mass spectrometry. PRACTICAL APPLICATION: This study provided a feasible approach to produce peptide antioxidants from sorghum kafirin. The novel naturally derived antioxidants could be potentially used as alternatives or synergetic components to synthetic antioxidants in improving the oxidative stability of various food products.

Characterization of protein hydrolysate from silkworm pupae (Bombyx mori)

Silkworm pupae (Bombyx mori) were subjected to drying, defatting, and hydrolysis using two enzymes: Alcalase and Neutrase. The degree of hydrolysis by Alcalase (9.61%) was much higher than for Neutrase (2.91%). Enzymatic hydrolysis increased the amount of total amino acid from 9.4 (raw material) to 42.56–62.37 mg/100 mg with the highest productivity obtained using Alcalase hydrolysis. The molecular weight of the hydrolysate using the Alcalase treatment was less than that using the Neutrase treatment. The antioxidant activity of both protein hydrolysates was higher than for the raw material with the decrease in IC50 (the inhibitory concentration required to inhibit 50% of 1,1-diphenyl-2-picrylhydrazyl radical) and the improvement of ferric reducing antioxidant power. Both enzymatic treatments improved the water solubility of dried and defatted samples. The foaming capacity and stability was improved by Neutrase hydrolysis. In contrast, the emulsifying properties were not obviously improved by either Alcalase hydrolysis or Neutrase hydrolysis. Practical applications Enzymatic hydrolysis could improve the physicochemical and functional properties of dried silkworm pupae. Protein hydrolysate from Neutrase hydrolysis provided excellent antioxidant activity, water solubility, and foaming properties. Therefore, it could be used as an ingredient for the development of food with high antioxidant activity and foaming characteristics. Protein hydrolysate from Alcalase hydrolysis provided high protein content, total amino acid content, and water solubility index. Therefore, it could be used as the ingredient for protein enrichment in food product development.

Purification and identification of peptides with high angiotensin-I converting enzyme (ACE) inhibitory activity from honeybee pupae (Apis mellifera) hydrolysates with in silico gastrointestinal digestion

The objective was to identify peptides with ACE inhibitory activity generated from honeybee pupae hydrolysates. In addition, we simulated gastrointestinal digestion and predicted the potential cleavage sites of the identified peptides. Peptides derived from honeybee pupae were cleaved in silico by pepsin, trypsin, and chymotrypsin using the PeptideCutter tool of ExPASy. Honeybee pupae were hydrolyzed using four different proteases (Alcalase, neutrase, trypsin, and papain), and their ACE inhibitory activity and distribution of molecular weights were determined. The neutrase hydrolysates showed the highest ACE inhibitory activity. Then, the hydrolysates were isolated and purified using ultrafiltration, gel filtration chromatography, and reversed-phased high performance liquid chromatography. Three novel ACE inhibitory peptides were identified by LC–MS/MS, AVFPSIVGR, PPVLVFV, and PGKVHIT, which exhibited the most potent ACE inhibitory activity, with IC50 values of 6.64, 47.7859, and 223.869 µM, respectively. In simulated in silico gastrointestinal digestion, peptides AVPFSIVGR and PGKVHIT had the position of cleavage sites by pepsin, chymotrypsin and trypsin, and PPVLVFV was cleaved by pepsin and chymotrypsin. We hope these results support the application of honeybee pupa hydrolysates as functional ingredients in foods and pharmaceuticals.

Antioxidant and ACE Inhibitory Activity of Enzymatic Hydrolysates from Ruditapes philippinarum.

Ruditapes philippinarum proteins were hydrolyzed by trypsin, neutrase, and pepsin. The antioxidant activities and ACE inhibitory activity of hydrolysates were analyzed and the antioxidant activities were related to their molecular weight distribution and amino acid compositions. Results indicated the hydrolysis of proteins led to an increase in small peptides and free amino acids. The antioxidant activities of Ruditapes philippinarum hydrolysates against DPPH radical scavenging, inhibition on linoleic acid peroxidation, and reducing power showed that the neutrase hydrolysate exhibited the strongest antioxidant activity. In addition, an ACE inhibition assay revealed that the pepsin hydrolysate had the highest ACE inhibitory ability. Ruditapes philippinarum protein hydrolysates could be a promising source of natural antioxidant and ACE inhibitory.

The influence of composite enzymatic hydrolysis on the antigenicity of β-conglycinin in soy protein hydrolysates

The β-conglycinin is considered one of the major soybean allergens. The effects of hydrolysis with Neutrase and Flavourzyme on the antigenicity of β-conglycinin were investigated by indirect competitive, enzyme-linked immunosorbent assay (ELISA) and western blotting analysis. The molecular weight distribution was performed by SDS-PAGE. The hydrolysate with the lowest antigenicity was further separated by ultrafiltration. The results showed that enzymatic hydrolysis significantly reduced the antigenicity of β-conglycinin in soy protein hydrolysates. Flavourzyme hydrolysis for 15 min, inactivating the enzyme and then Neutrase hydrolysis for 15 min was the optimal combination of enzymatic hydrolysis, and the antigenicity of β-conglycinin in the hydrolysates was reduced by 64.46% compared with unhydrolyzed soy protein. The molecular weight distributions of hydrolysates were 31, 26, 20, and 15 kDa or lower. The low molecular weight (<10 kDa) ultrafiltration fractions exhibited the lowest antigenicity. Practical applications Enzymatic hydrolysis could be an efficient method in the reduction of soybean protein antigenicity. Flavourzyme hydrolysis for 15 min, inactivating the enzyme and then Neutrase hydrolysis for 15 min was the optimal hydrolysis mode for the reduction of β-conglycinin antigenicity. The results suggested that less than 10 kDa ultrafiltration fractions of hydrolysates showed the lowest antigenicity, which could be useful in the development of hypoallergenic soybean peptide powder.

INFLUENCE OF FACTORS ON THE BITTERNESS AND SENSORY TASTE IN PROTEIN HYDROLYSATE FROM SPENT

Spent brewer’s yeast, obtained after the main fermentation stage, is a rich- in-protein source (protein content accounts for 48 - 50 % dry matter). In order to use efficiently this protein source for using in food industry, it was hydrolysed by different methods into mixtures of peptides and amino acids. So that it has a wide range of applications in food. It can be used as emulsifying agents in a number of applications such as salad dressings, spreads, ice cream, coffee whitener, cracker, and meat products like sausages. However, bitterness in hydrolysates is one of the major undesirable aspects for various applications in food processing. In this study, influences of factors (E/S ratio, pH and temperature) on bitterness of hydrolysate were studied to choose the best hydrolysis conditions by using flavourzyme, alcalase and neutrase. The bitterness of hydrolysate was determined by intensity sensory method (using quinine standard) and amino acid content was analysed by HPLC method. The result showed that bitterness of brewer’s yeast hydrolysate by flavourzyme is the lowest and that by neutrase is the highest. In particular, the bitterness of hydrolysates have reached values of 15.2–40.42 µmol quinine/l (FH - flavourzyme hydrolysate), 21–64.99 µmol quinine/l (AH - alcalase hydrolysate) and 34.62–64.26 µmol quinine/l (NH - neutrase hydrolysate), respectively. The hydrolysis conditions in using flavourzyme were chosen at 50 oC, pH 7, E/S ratio 7.1U/g and in using alcalase - at 55 oC, pH 8, ratio E/S 7.2 U/g, respectively. At this conditions, bitterness reached values 15.44 µmol quinine/l (in FH) and 21.16 µmol quinine/l (in AH).