Food-derived protein hydrolysates and peptides:anxiolytic and antidepressant activities,characteristics,and mechanisms

Globally,the prevalence of anxiety and depression has reached epidemic proportions.Food-derived protein hydrolysates and peptides delivered through dietary supplementation can avoid the negative risks associated with traditional pharmaceuticals while delivering superior anxiolytic and antidepressant effects.This review summarizes current research on food-derived anxiolytic and antidepressant protein hydrolysates and peptides,and subsequently analyses their physicochemical characteristics and elaborates on their mechanisms.The aim of this work is to contribute to the in-depth study and provide a theoretical foundation for the development of related products to better serve patients with anxiety and depression.

Preparation,characterization and antioxidant activity analysis of three Maillard glycosylated bone collagen hydrolysates from chicken,porcine and bovine

Bone collagen hydrolysates(peptides)derived from byproduct of animal product processing have been used to produce commercially valuable products due to their potential antioxidant activity.Maillard glycosylated reaction is considered as a promising method to enhance the antioxidant activity of peptides.Hence,this research aims at investigating the Maillard glycosylation activity and antioxidant activity of bone collagen hydrolysates from different sources.In this study,3 glycosylated bone collagen hydrolysates were prepared and characterized,and cytotoxicity and antioxidant activity were analyzed and evaluated.The free amino groups loss,browning intensity,and fluorescence intensity of G-Cbcp(glycosylated chicken bone collagen hydrolysates(peptides))were the heaviest,followed by G-Pbcp(glycosylated porcine bone collagen hydrolysates(peptides))and G-Bbcp(glycosylated bovine bone collagen hydrolysates(peptides)).The results of amino acid analysis showed that amino acid composition of different bone collagen hydrolysates was significantly different and the amino acid decreased to different degrees after Maillard glycosylated reaction,which may lead to differences in Maillard glycosylated reaction activity.Furthermore,the 3 glycosylated hydrolysates showed no significant cytotoxicity.The results showed that glycosylation process significantly increased the antioxidant activity of bone collagen hydrolysates,and G-Cbcp showed the strongest antioxidant activity,followed by G-Pbcp and G-Bbcp.Therefore,compared with the bone collagen hydrolysates,3 glycosylated hydrolysates showed significant characteristic and structural changes,and higher antioxidant activity.

Calcium-binding ability of soy protein hydrolysates

This present study investigated the ability of various soy protein hydrolysates (SPHs) in binding calcium. It was demonstrated that the amount of Ca-bound depended greatly on the SPHs obtained using different proteases, which included: neutrase, flavourzyme, protease M and pepsin. The maximum level of Ca-bound (66.9 mg/g) occurred when protease M was used to hydrolyze soy protein. Peptide fragments exhibiting high Ca-binding capacity had molecular weights of either 14.4 or 8–9 kDa. The level of Ca-bound increased linearly with the increment of carboxyl content in SPHs, and further deamidation on SPHs from protease M improved Ca-binding of the hydrolysate.

Study on Enzymatic Hydrolysis of Gadus morrhua Skin Collagen and Molecular Weight Distribution of Hydrolysates

Process parameters on enzymatic hydrolysis and molecular weight （MW） distribution of collagen hydrolysates from Gadus morrhua skin were investigated. The optimal process parameters were obtained by the single-factor and orthogonal experiments. The molecular weight distribution of hydrolysates was determined using both Sephadex G25 partition and high speed liquid chromatography electricity spray mass spectrum （HPLC-ESI-MS）. Collagen hydrolysates were first gained by an alkaline protease ＂alcalase＂ for 3 h at temperature （50~C）, pH （10.0）, substrate concentration （75 g L-~）, and E/S （3%）. The molecular weight distribution of collagen hydrolysates ranged from 300 to 1 500 Da, and most of peptides were under 1 200 Da. Sephadex G25 partition and HPLC-ESI-MS should be successfully employed to determine the molecular weight distribution of collagen hydrolysates.

Effects of brewers' spent grain protein hydrolysates on gas production, ruminal fermentation characteristics, microbial protein synthesis and microbial community in an artificial rumen fed a high grain diet

Background: Brewers' spent grain(BSG) typically contains 20% – 29% crude protein(CP) with high concentrations of glutamine, proline and hydrophobic and non-polar amino acid, making it an ideal material for producing valueadded products like bioactive peptides which have antioxidant properties. For this study, protein was extracted from BSG, hydrolyzed with 1% alcalase and flavourzyme, with the generated protein hydrolysates(AlcH and FlaH)showing antioxidant activities. This study evaluated the effects of AlcH and FlaH on gas production, ruminal fermentation characteristics, nutrient disappearance, microbial protein synthesis and microbial community using an artificial rumen system(RUSITEC) fed a high-grain diet.Results: As compared to the control of grain only, supplementation of FlaH decreased(P < 0.01) disappearances of dry matter(DM), organic matter(OM), CP and starch, without affecting fibre disappearances;while AlcH had no effect on nutrient disappearance. Neither AlcH nor FlaH affected gas production or VFA profiles, however they increased(P < 0.01) NH_3-N and decreased(P < 0.01) H_2 production. Supplementation of FlaH decreased(P < 0.01)the percentage of CH_4 in total gas and dissolved-CH_4(dCH_4) in dissolved gas. Addition of monensin reduced(P < 0.01) disappearance of nutrients, improved fermentation efficiency and reduced CH_4 and H_2 emissions.Total microbial nitrogen production was decreased(P < 0.05) but the proportion of feed particle associated(FPA) bacteria was increased with FlaH and monensin supplementation. Numbers of OTUs and Shannon diversity indices of FPA microbial community were unaffected by AlcH and FlaH;whereas both indices were reduced(P < 0.05) by monensin. Taxonomic analysis revealed no effect of AlcH and FlaH on the relative abundance(RA) of bacteria at phylum level, whereas monensin reduced(P < 0.05) the RA of Firmicutes and Bacteroidetes and enhanced Proteobacteria. Supplementation of FlaH enhanced(P < 0.05) the RA of genus Prevotella, reduced Selenomonas, Shuttleworthia, Bifidobacterium and Dialister as compared to control;monensin reduced(P < 0.05) RA of genus Prevotella but enhaced Succinivibrio.Conclusions: The supplementation of FlaH in high-grain diets may potentially protect CP and starch from ruminal degradation, without adversely affecting fibre degradation and VFA profiles. It also showed promising effects on reducing CH_4 production by suppressing H_2 production. Protein enzymatic hydrolysates from BSG using flavourzyme showed potential application to high value-added bio-products.

Protein hydrolysates in animal nutrition：Industrial production, bioactive peptides,and functional significance

Recent years have witnessed growing interest in the role of peptides in animal nutrition. Chemical, enzymatic, or microbial hydrolysis of proteins in animal by-products or plant-source feedstuffs before feeding is an attractive means of generating high-quality small or large peptides that have both nutritional and physiological or regulatory functions in livestock, poultry and fish. These peptides may also be formed from ingested proteins in the gastrointestinal tract, but the types of resultant peptides can vary greatly with the physiological conditions of the animals and the composition of the diets. In the small intestine, large peptides are hydrolyzed to small peptides,which are absorbed into enterocytes faster than free amino acids（AAs） to provide a more balanced pattern of AAs in the blood circulation. Some peptides of plant or animal sources also have antimicrobial, antioxidant,antihypertensive, and immunomodulatory activities. Those peptides which confer biological functions beyond their nutritional value are called bioactive peptides. They are usually 2–20 AA residues in length but may consist of 〉20AA residues. Inclusion of some（e.g. 2–8%） animal-protein hydrolysates（e.g., porcine intestine, porcine mucosa,salmon viscera, or poultry tissue hydrolysates） or soybean protein hydrolysates in practical corn-and soybean mealbased diets can ensure desirable rates of growth performance and feed efficiency in weanling pigs, young calves,post-hatching poultry, and fish. Thus, protein hydrolysates hold promise in optimizing the nutrition of domestic and companion animals, as well as their health（particularly gut health） and well-being.

The Inhibiting Effect of Bone Protein Hydrolysates on Lipid Oxidation in Pork Patties

Bone protein hydrolysates were prepared by limited alcalase hydrolysis （5 h）. The hydrolysates were formulated （0-3%, w/w） into pork patties to determine the antioxidant efficacy. 0.02% BHA （butylated hydroxyanisole） was used as a positive control. Lipid oxidation in patties during storage was analyzed by measuring the TBARS and protein carbonyl content. The results showed that bone protein hydrolysates possessed significant antioxidant activity, and antioxidant activity increased with the increasing hydrolysates concentration. Sensory evaluation indicated that bone protein hydrolysates improved the color and decreased lipid oxidation flavor of pork patties. The 2% bone hydrolysates possessed the highest antioxidant activity and better sensory quality, and its effect was closed to 0.02% BHA.

Fractionation of edible bird’s nest glycoprotein hydrolysates:characterisation and antioxidative activities of the fractions

E dible bird’s nest(EBN)hydrolysates have been proven to exhibit enhanced bioactivities.However,being a macromolecule,fractions with different molecular weights would have different properties and bioactivities.Hence,this research was aimed to determine the chemical properties and antioxidant activities of freezedried(EBN_(FD))and spray-dried EBN(EBN_(SD))hydrolysates fractionated using gel permeation chromatography(GPC).Overall,two well-separated fractions were identified(EBN_(fFD1),EBN_(fFD2),EBN_(fSD1) and EBN_(fSD2)).EBNFD demonstrated significantly higher(P≤0.05)peptide(3.6%),total carbohydrate(27.7%)and sialic acid(18.2%)contents than that of EBNSD.Similar trend was observed in low molecular weight fractionates(EBN_(fFD2) and EBN_(fSD2)).Meanwhile,the first fractionates(EBN_(fFD1) and EBN_(fSD1))exhibited significantly higher(P≤0.05)hydroxyl radical(·OH)scavenging activity.Fourier transform infrared(FTIR)spectroscopy demonstrated that all EBN fractionates have similar spectrum,except in the region of N—H(amideⅡ)and C—H alkyl group.In conclusion,EBN fractionates with different molecular weights showed different chemical properties and antioxidant activities.

Lima Bean(Phaseolus lunatus)Protein Hydrolysates with ACE-I Inhibitory Activity

Several protein sources can be used to produce bioactive peptides with angiotensin I-converting enzyme (ACE) inhibittory activity. Protein concentrates from ungerminated and germinated lima bean Phaseolus lunatus seed flours were hydrolyzed with Alcalase 2.4 L or pepsin-pancreatin sequential hydrolysis, and ACE inhibitory activity measured in the different hydrolysis treatments. Protein hydrolysate production was analyzed with a 23 factorial design with four replicates of the central treatment. Evaluated factors were protein concentrate source (ungerminated seeds, PC1;germinated seeds, PC2), enzyme/substrate ratio E/S (1/50 or 1/10) and hydrolysis time (0.5 or 2.0 h for Alcalase;1 or 3 h for pepsin-pancreatin). Degree of hydrolysis (DH) was high for the Alcalase hydrolysates (24.12% 58.94%), but the pepsin-pancreatin hydrolysates exhibited the highest ACE inhibitory activity (IC50 = 0.250 0.692 mg/mL). Under the tested conditions, the hydrolysates with the highest ACE inhibitory activity were produced with sequential pepsin-pancreatin using either PC1 at 1 h hydrolysis time and a 1/10 E/S ratio or PC2 at 1 h hydrolysis time and a 1/50 E/S ratio. Lima bean protein hydrolysates prepared with Alcalase or pepsin-pancreatin are a potential ingredient in the production of physiologically functional foods with antihypertensive activity.

Anti-tumor activity of rice bran hydrolysates on migration, invasion and angiogenesis

Objective:To investigate anti-tumor effect of rice bran hydrolysates(RBH)on proliferation,migration,invasion,and angiogenesis of cholangiocarcinoma(CCA)cells,and elucidate the underlying mechanisms.Methods:RBH was prepared from Tubtim Chumprae rice(Oryza sativa L.)by hydrothermolysis followed by protease digestion.Phenolic content in RBH was analyzed by high-performance liquid chromatography.Human CCA cells,KKU-156,KKU-452,and KKU-100,were used to study the effects of RBH on proliferation,migration,invasion,and adhesion by wound healing,Transwell chamber,and fibronectin cell adhesion assays.Angiogenesis was evaluated using human umbilical vein endothelial cells.Proteins associated with cancer progression were analyzed by immunobloting assays.Results:RBH contained carbohydrates,proteins,lipids,and various phenolic compounds and flavonoids.RBH did not inhibit CCA proliferation,but strongly suppressed migration,invasion,adhesion of CCA cells,and the formation of tube-like capillary structures of human umbilical vein endothelial cells.Moreover,RBH downregulated phosphorylation of FAK,PI3K,and Akt,suppressed NF-κB nuclear translocation,decreased the expression of ICAM-1,vimentin and vascular endothelium growth factor(VEGF),and increased the expression of E-cadherin.Conclusions:RBH suppresses CCA cell migration and invasion and decreases expression of proteins involved in cancer metastasis.RBH is a potential food supplement for cancer prevention.

Protective effects of rice bran hydrolysates on heart rate variability,cardiac oxidative stress,and cardiac remodeling in high fat and high fructose diet-fed rats

Objective:To examine the ameliorative effect of rice bran hydrolysates(RBH)on metabolic disorders,cardiac oxidative stress,heart rate variability(HRV),and cardiac structural changes in high fat and high fructose(HFHF)-fed rats.Methods:Male Sprague-Dawley rats were daily fed either standard chow diet with tap water or an HFHF diet with 10%fructose in drinking water over 16 weeks.RBH(500 and 1000 mg/kg/day)was orally administered to the HFHF-diet-fed rats during the last 6 weeks of the study period.At the end of the treatment,metabolic parameters,oxidative stress,HRV,and cardiac structural changes were examined.Results:RBH administration significantly ameliorated metabolic disorders by improving lipid profiles,insulin sensitivity,and hemodynamic parameters.Moreover,RBH restored HRV,as evidenced by decreasing the ratio of low-frequency to highfrequency power of HRV,a marker of autonomic imbalance.Cardiac oxidative stress was also mitigated after RBH supplementation by decreasing cardiac malondialdehyde and protein carbonyl,upregulating eNOS expression,and increasing catalase activity in the heart.Furthermore,RBH mitigated cardiac structural changes by reducing cardiac hypertrophy and myocardial fibrosis in HFHFdiet-fed rats.Conclusions:The present findings suggest that consumption of RBH may exert cardioprotective effects against autonomic imbalances,cardiac oxidative stress,and structural changes in metabolic syndrome.

Sang-Yod rice bran hydrolysates alleviate hypertension, endothelial dysfunction, vascular remodeling, and oxidative stress in nitric oxide deficient hypertensive rats

Objective:To evaluate the potential therapeutic effect of Sang-Yod rice bran hydrolysates(SRH)and in combination with lisinopril against hypertension,endothelial dysfunction,vascular remodeling,and oxidative stress in rats with nitric oxide deficiency-induced hypertension.Methods:Hypertension was induced in male Sprague-Dawley rats by administration of a nitric oxide synthase inhibitor,Nω-nitro-L-arginine methyl ester(L-NAME)in drinking water for 6 weeks.Hypertensive rats were administered daily with SRH(500 mg/kg/day),lisinopril(1 mg/kg/day),or the combination of SRH and lisinopril by gastric lavage for the last 3 weeks of L-NAME treatment.Hemodynamic status,vascular reactivity to vasoactive agents,and vascular remodeling were assessed.Blood and aortic tissues were collected for measurements of oxidative stress markers,plasma angiotensin-converting enzyme(ACE)activity,plasma angiotensinⅡ,and protein expression.Results:L-NAME induced remarkable hypertension and severe oxidative stress,and altered contents of smooth muscle cells,elastin,and collagen of the aortic wall.SRH or lisinopril alone reduced blood pressure,restored endothelial function,decreased plasma ACEs and angiotensinⅡlevels,alleviated oxidant markers and glutathione redox status,and restored the vascular structure.The effects were associated with increased expression of endothelial nitric oxide synthase and decreased expression of gp91phox and AT1R expression.The combination of SRH and lisinopril was more effective than monotherapy.Conclusions:SRH alone or in combination with lisinopril exert an antihypertensive effect and improve endothelial function and vascular remodeling through reducing oxidative stress and suppressing elevated renin-angiotensin system.

Extraction Hydrolysates from Larimichthys Polyactis Swim Bladder Using Enzymatic Hydrolysis

As a kind of biopolymer,hydrolysates of fish swim bladder,safer than those of land mammals,are widely used in food,cosmetics as well as pharmaceutical and biomedical fields for their biocompatibility,biodegradability,and weak antigenicity.To enhance hydrolysate production,in this paper,the papain and alcalase hydrolysis processes of larimichthys polyactis swim bladder were optimized with orthogonal experiments.With 89.5%hydrolysate yield,the optimal processing conditions for alcalase were solid-liquid ratio of 1:30,enzyme concentration of 0.7%,and extraction time of 6 h.As for papain,under the optimal processing conditions:solid-liquid ratio of 1:20,enzyme concentration of 0.5%,and extraction time of 8 h,the hydrolysate yield was 65.1%.To obtain higher hydrolysate yields,the ultrasonic pretreatments were implemented before the optimal enzyme hydrolysis processes.With ultrasonic waves of 100 W for 50 min,the hydrolysate yields were increased 2.1%(alcalase)and 4.5%(papain),respectively.The Fourier Transform Infrared(FTIR)spectroscopic analysis revealed that the hydrolysates extracted by papain exist in triple-helical forms.The Ultra-Violet(UV)absorption spectra indicated that the aromatic amino acids in the hydrolysates had strong absorptions in the wavelength range of 240 nm–300 nm.The results of this research demonstrate that the alcalase hydrolysates have better solubility in water and the solution is more stable under ambient temperature.However,the hydrolysates extracted by papain have a gel property and are insoluble in weak acid at room temperature,which is more suitable for applications in feedstock of biomedical.

Protective effects of tilapia(Oreochromis niloticus)skin gelatin hydrolysates on osteoporosis rats induced by retinoic acid

Tilapia skin gelatin hydrolysates(TSGH)were obtained by complex protease hydrolysis.The amino acid sequences of 50 peptides in TSGH were identified,and most of these peptides were found to contain the-Gly-Pro-sequence.The osteoporosis(OP)rat model induced by retinoic acid was prepared,and the effects of different doses of TSGH on OP in vivo were evaluated.Serum calcium(Ca)and phosphate(P),alkaline phosphatase activity,and osteocalcin levels in OP rats were regulated by TSGH.The bone length,dry weight index,maximum load,and Ca content of OP rats significantly increased by treatment TSGH in a dosedependent manner.Micro-CT images of the femurs and tibias of the rats indicated that the bone mineral density,cortical bone thickness,and cortical/trabecular bone area ratios were recovered and that OP symptoms were improved.Tartrate-resistant acid phosphate and hematoxylin-eosin staining showed that osteoclast numbers and histomorphological changes in the femurs in OP rats could be recovered by TSGH.

Dietary Combination of Fish Oil and Hemoglobin Hydrolysates Alters Serum and Liver Lipid Contents in Rat

Fish oil has been shown to have anti-inflammatory and anti-cancer effects, and to reduce serum triacylglycerol (TAG) levels by stimulating lipid oxidation and inhibiting lipogenesis in the liver. A small number of studies have demonstrated the synergistic effect of fish oil and other bioactive components. This study examined the effect of fish oil in combination with porcine hemoglobin (Hb) hydrolysates on serum and liver lipid contents in rats. Male Wistar rats were divided into four groups;one group was fed a casein and soybean oil-based semi-purified basal diet and other three groups were fed the basal diet supplemented with 2% fish oil, 0.175% Hb hydrolysates, and 2% fish oil plus 0.175% Hb hydrolysates, respectively, for 4 weeks. The fish oil diet decreased serum and liver TAG contents but did not change serum and liver cholesterol levels. The dietary combination of fish oil and Hb hydrolysates decreased serum and liver TAG and cholesterol contents owing to the additive effect of both compounds, and this diet reduced the serum non-high-density lipoprotein cholesterol content as a result of a synergistic effect. This hypolipidemic effect was in part caused by enhanced excretion of fecal fatty acids, neutral steroids, and acidic steroids. The results of this study suggest that the combined intake of fish oil and Hb hydrolysates may play beneficial roles in the prevention of cardiovascular disease as compared with fish oil alone.

Effect of Different Treatments on Antioxidative Stability of the Scallop Protein Hydrolysates

Effects of different treatments on the antioxidant activity of scallop protein hydrolysates (SPH) were evaluated using DPPH radical scavenging activity and reducing power. Results showed that the antioxidant activity of SPH had good heating-resistance from 25°C to 65°C. The antioxidant activity of SPH could retain under acidic environment, but rapidly reduced under alkaline conditions. Addition of D-galactose, D-xylose, and D-fructose at 65°C could increase the antioxidant activity of SPH, but no such effect was not observed at this temperature. With the increase of storage time, the antioxidant activity of SPH gradually decreased. Moreover, pepsin digestion treatment slightly reduced the antioxidant activity of SPH, and further trypsin and mixed enzyme (trypsin + chymotrypsin) digestion significantly reduced this activity (p < 0.05). In conclusion, SPH may be used as food ingredients or food supplements in different food fields.

Novel Antioxidant Peptides Derived from Enzymatic Hydrolysates of Macadamia Protein

In the present work, macadamia protein was enzymatic hydrolyzed to produce peptides which had abundant antioxidant activities. The relative antioxidant capacity was investigated through some in vitro models such as scavenging activity of DPPH radical, scavenging of ABTS+ radical and evaluation of the total antioxidant capacity assay. Macadamia protein was characterized by methods of DEAE cellulose cation-exchange chromatography and SDS-PAGE. Besides, method of price graph was used to compare the difference and to investigate the connection between the actual and ideal antioxidant value of the hydrolysates, aiming to reduce this difference.

Improvement of Vitis amurensis Rupr.grape quality by using fish protein hydrolysates as fertilizer

High quality wine grape is the first factor to satisfy the wine-maker to produce superior quality wines.In this work,a fish protein hydrolysates derived from deep-sea salmon or cod,was used as fertilizer to improve Shuanghong(Vitis amurensis Rupr.)grape quality.Application of powder fish protein hydrolysates fertilizer by spraying directly to foliar(4.5 kg/ha),to root(4.5 kg/ha)or to the both foliar(4.5 kg/ha)and root(4.5 kg/ha)were carried out respectively,during the period from 2–3 weeks before flowering until 2–3 weeks before harvest.Grape sampling was made at both veraison and harvest.Different classes of phenolic compounds,including 10 phenolic acids and 11 proanthocyanidins in grape seeds and 10 anthocyanins in grape skins were determined by UHPLC or HPLC;total anthocyanins and total polyphenols in grape skins were determined by spectrophotometric method.Antioxidant activities of the phenolic compounds were evaluated by ABTS and FRAP methods.The results showed that the application of fish protein hydrolysates fertilizer to both root and foliar led to a significant improvement of berry quality at harvest/maturity,i.e.,increasing 12.13%total polyphenols(TP),8.3%total anthocyanins 11.03%ABTS and 45.81%FRAP compared with control.Besides,both root and foliar application resulted in the highest individual anthocyanins and proanthocyanidins in grapes.These results suggest that the both root and foliar application could be of great interest for the viticulturists to produce grapes with higher polyphenolic content and antioxidant activity.Although this work was experimented with Vitis amurensis Rupr.grapes,the proposed methods would also be applicable to other grape varieties for the purposes of increasing anthocyanin or polyphenol contents.

Antihypertensive Properties on Spontaneously Hypertensive Rats of Peptide Hydrolysates from Silkworm Pupae Protein

Peptide hydrolysates of silkworm pupae protein with molecular weight of less than 5000 Da were prepared by ultrafiltration. The extracted peptide hydrolysates of silkworm pupae protein had inhibitory action on angiotensin-I-converting enzyme activity in vitro. The hydrolysates were orally administered to spontaneously hypertensive rats (SHR) in one period and long-term (four weeks). The results showed that the systolic blood pressure (SBP) of the treatment groups decreased in a dose-related manner. After one oral administration of silkworm protein hydrolysates with doses of 60, 20 and 5 mg/kg, the SBP of SHR decreased by 21.5, 13.8, and 9.0 mmHg in 1.5 h. After four weeks of the treatment in 80 mg/kg, the SBP decreased by 25 mmHg, with the antihypertensive activity close to 4 mg/kg of captopril;the SBP of the 40 mg/kg dose group also decreased by 17.5 mmHg. The peptide hydrolysate did not affect the SBP in normal, non-hypertensive rats in one period and long-term treatments. The acute toxicity research showed that the peptide hydrolysates were safe and without side effects. This research would be helpful in exploring the silkworm protein peptides as functional components for the antihypertension treatment.

Peptidomic analysis of whey protein hydrolysates and prediction of their antioxidant peptides

Enzymatic hydrolysis of proteins is a breakdown process of peptide bond in proteins,releasing some peptides with potential biological functions.Previous studies on enzymatic hydrolysis of whey proteins have not identified the complete peptide profiles after hydrolysis.In this study,we reconstructed a profile of peptides from whey hydrolysates with two enzymes and different processing conditions.We also developed an ensemble machine learning predictor to classify peptides obtained from whey hydrolysis.A total of 2572 peptides were identified over three process conditions with two enzymes in duplicate.499 peptides were classified and chosen as potential antioxidant peptides from whey proteins.The peptides classified as antioxidants in the hydrolysates had a proportion of 13.1%-24.5%regarding all peptides identified.These results facilitate the selection of promising peptides involved in the antioxidant properties during the enzymatic hydrolysis of whey proteins,aiding the discovery of novel antioxidant peptides.