Pepsin Hydrolysis Research Articles

Production of Protein Hydrolysates Teff (Eragrostis tef) Flour with Antioxidant and Angiotensin-I-Converting Enzyme (ACE-I) Inhibitory Activity Using Pepsin and Cynara cardunculus L. Extract.

In recent years, several studies have shown the antioxidant and antihypertensive potential of bioactive peptides. Thus, bioactive peptides are likely to be a valuable substance for the development of functional foods. There are a wide variety of sources of these peptides, including several cereals. Teff is an Ethiopian-rooted cereal with an interesting nutritional profile, mainly due to its high amount of protein. In this study, teff flour was subjected to a defatting process for optimizing the protein extraction. Such extraction was performed by precipitation from its isoelectric point, a crucial step that separates the protein from other components based on their charge. The protein obtained was subjected to enzymatic hydrolysis by pepsin and Cynara cardunculus L. The antihypertensive (angiotensin-I-converting enzyme -ACE-I- inhibitory activity) and antioxidant activity (2,2-diphenyl-1-picrylhydrazyl -DPPH- radical scavenging activity) of the peptides were determined. According to the IC50 values, the results obtained showed that the peptides from teff flour show promising bioactivity compared to other cereals. Furthermore, the peptides from teff flour obtained from C. cardunculus L. showed higher antioxidant activity (defatted teff flour -DTF-: 0.59 ± 0.05; protein extract -EP- : 1.04 ± 0.11) than those obtained with pepsin (DTF: 0.87 ± 0.09; EP: 1.73 ± 0.11). However, C. cardunculus L. hydrolyzate peptides showed lower inhibitory activity of ACE-I (DTF: 0.59 ± 0.07; EP: 0.61 ± 0.05) than the pepsin hydrolyzate (DTF: 0.15 ± 0.02; EP: 0.33 ± 0.05).

Protein digestibility in wheat noodles: The inhibitory effect and its mechanism of wheat bran dietary fiber

This study investigated the effects of different wheat flour extraction rate (35–95%) on the protein digestibility of those noodles. And to further elucidate the internal mechanism of above phenomenon, wheat flour with different amounts of wheat bran dietary fiber (WBDF) was produced by adding endogenous WBDF. Results indicated that protein digestibility rose significantly with increasing flour extraction rate, peaking at 91.85% at 80% extraction, before trending downward to 85.71% at 95% extraction. Further, among noodles containing different WBDF content, increasing WBDF content to 6% enhanced the formation of β-sheets, boosting I755 levels and reducing I854/I830 levels, thus decreasing protein digestibility. As WBDF content rose further, it promoted transition from β-sheets to β-turn, decreasing I755 and increasing I854/I830, enhancing protein digestibility slightly. The changes indicated that low level of WBDF induced a more compact protein secondary structure to inhibit protein digestion. Conversely, in noodles with high level of WBDF (>6%), the looser protein secondary structure partially alleviated the inhibitory effect of WBDF on protein digestion, which was caused by part of WBDF penetrating the protein's hydrophobic core. Moreover, the static quenching effect of WBDF on pepsin hydrolysis sites through hydrophobic interaction, especially the tyrosine, was another significant factor inhibiting protein digestion.

Effect of ultrasound and enzymatic pre-treatments on the profile of bioactive peptides of beef liver hydrolysates

The use of meat by-products as a potential source of protein hydrolysates rich in bioactive peptides is of growing interest to valorise these products and improve their sustainable use. This study aimed to evaluate the effect of different pre-treatments (hydrolysis with pepsin, ultrasounds, and ultrasounds-assisted pepsin hydrolysis) on the peptide profile and bioactivity of beef liver hydrolysed with flavourzyme. The pre-treatments with pepsin increased the degree of hydrolysis and generation of free amino acids in the liver hydrolysates, whereas the subsequent hydrolysis with flavourzyme influenced the molecular weight distribution of the peptides. Samples pre-treated with pepsin and ultrasounds-assisted pepsin hydrolysates showed the highest values of antioxidant and inhibitory activity of ACE-I, ECE-I, DPP-IV, and neprilysin enzymes, and therefore these hydrolysates were characterised to obtain the bioactive peptide profiles. A total of 995 peptides were identified by tandem mass spectrometry in the most active fractions separated by reversed-phase liquid chromatography, and 20 of them were predicted as potentially responsible for the observed bioactivities and subsequently characterised by in silico tools. These results evidenced the potential of hydrolysis pre-treatments with pepsin and ultrasounds-assisted pepsin to obtain beef liver hydrolysates rich in bioactive peptides that could exert multifunctional bioactivities such as antioxidant, antihypertensive, and antidiabetic, while giving added value to this meat by-product.

Acid-soluble collagen (ASC) hydrolysate from Javanese goat (Capra aegagrus hocus) skin: effect of pepsin hydrolysis and antioxidant activity

Abstract Javanese goat (Capra aegagrus hocus) is an animal species which have many populations in Indonesia and it is used because more selective in feed, especially Leguminosae and seeds which of rich in collagen. The study aims to determine the impact of hydrolysis time and antioxidant activities on the extraction of skin Javanese goats using the acid-soluble collagen (ASC) method. The ASC used in this investigation was taken from another study and hydrolyzed with pepsin throughout the course of 0, 30, 60, 90, and 120 minutes of incubation. The success of the hydrolysis process can be shown by the percent degree of hydrolysis. Methods are used to determine the percent degree of hydrolysis of the TCA method. Results showed that hydrolyzing for 60 min yields the highest total soluble collagen of ASC, with a value of 0.77 mg/ml. Finally, the ASC which is hydrolysis use pepsin for 60 min has a degree of hydrolysis, and total soluble collagen is the highest. The protein molecular weight of ASC which is the hydrolysis of 60 min is smaller than before hydrolysis and it has radical scavenging activity of 56.42% ± 1.45. So far, ASC from Javanese goat (Capra aegagrus hocus) has been hydrolyzed in this study has high antioxidant activity and can be recommended as a substitute for functional food.

Isolation and purification of angiotensin converting enzyme inhibitory peptide from goat milk hydrolysate by ultrafiltration membrane

Hypertension been a significant risk factor for cardiovascular illness. Synthesized angiotensin converting enzyme (ACE) inhibitors are active antihypertensive medicines they frequently generate unwanted side effects. This study describes the isolation and purification of an ACE inhibitory peptide from goat milk hydrolysate (Sahel breed). Hydrolysates containing angiotensin converting enzyme (ACE) inhibitory peptide were produced from goat milk by pepsin and trypsin. The strongest ACE inhibitory action was found in pepsin hydrolysate (57%) at 12h, hence was further purified. Purification was done using a 10 kDa ultrafiltration membrane and three steps of RP-HPLC to obtain ACE inhibitory peptide with activity of 84% and IC50 of 3.25±0.11 μg/ml. Lineweaver–Burks’ plots showed that the inhibitory kinetic mechanism of this peptide was competitive. In conclusion, ACE inhibitory peptide from goat milk hydrolysate treated with pepsin may be positive constituent to serve as drug against hypertension.

A new antimicrobial food peptide: characteristics, properties and effectiveness evaluation

Promising candidates as antibacterial drugs are antimicrobial peptides (AMP) present in cow colostrum. The aim of the research is to isolate, theoretically substantiate and confirm the biological activity of a new AMP from pepsin hydrolysate of cow colostrum with the amino acid sequence EKLAKNKLARGLKRK. According to the Protein NCBI database, the isolated AMP is identified as AW655195.1 105840 MARC 1BOV/ Bos taurus (cattle). When identifying AMP from the database of antimicrobial peptides APD, it was not found. When identifying AMP using the DRAMP database, the object under study is missing, but its characteristics belong to the antimicrobial class. The total hydrophobic ratio of the peptide determined by APD is 33%. The total net charge is +6, the molecular weight is 1753.151 Da. Protein binding potential (Boman index) at 3.44 kcal/mol. The selected AMP is close in characteristics to the known ones included in the APD database. AMP belongs to the cationic hydrophobic α-helical, which suggests its antimicrobial activity. As a result of in vitro experiments, the antimicrobial and antitumor activity of the peptide has been proven.

Protein identification and potential bioactive peptides from pumpkin (Cucurbita maxima) seeds.

Pumpkin is an economically important crop all over the world. Approximately, 18%-21% of pumpkins, consisting of peels and seeds by-products, are wasted during processing. In addition, the seeds are rich in protein and have the potency of bioactive peptide production. This study aims to recognize the proteins and investigate the potential bioactive peptides from pumpkin (Cucurbita maxima) seeds. Pumpkin seeds were subjected to hot air drying (HAD) at 55°C for 12 h and freeze-drying (FD) at -80°C for 54 h before they were powdered, analyzed, and precipitated by isoelectric point to obtain pumpkin seed protein isolates (PSPI). PSPI comprised 11S globulin subunit beta, 2S seed storage albumin, and chaperonin CPN60-1. To generate hydrolysate peptides, PSPI was hydrolyzed using papain, pepsin, and bromelain. FD group pepsin hydrolysates had the highest peptide content of 420.83 mg/g. ACE inhibition and DPP-IV inhibition activity were analyzed for each enzymatic hydrolysate. The pepsin hydrolyzed sample exhibited the highest ACE inhibition of 70.26%, and the papain hydrolyzed sample exhibited the highest DPP-IV inhibition of 30.51%. The simulated gastrointestinal digestion (SGID) conducted by pepsin and pancreatin increased ACE inhibitory activity from 76.93% to 78.34%, and DPP-IV inhibited activity increased from 58.62% to 77.13%. Pepsin and papain hydrolysates were fractionated using ultrafiltration to measure ACE and DPP-IV inhibition activity. The highest free radical scavenging abilities were exhibited by the <1 kDa hydrolysate fractions with 78.34% ACE inhibitory activities and 79.55% DPP-IV inhibitory activities. This research revealed that pumpkin seeds had the potency to produce bioactive peptides.

Assessing and optimizing the bioactivities of diverse enzyme-derived protein hydrolysates from Porphyra yezoensis: unlocking the health potential.

The interest in algae-derived bioactive compounds has grown due to their potential therapeutic efficacy against a range of diseases. These compounds, derived from proteins, exhibit diverse functions and profound pharmacological effects. Recent research has highlighted the extensive health benefits of algae-derived bioactive compounds, positioning them as potential natural antioxidants in the food, pharmaceutical, and cosmetic industries. This study focuses on extracting proteins from Porphyra yezoensis using innovative physical pre-treatment methods such as stirring, ball milling, and homogenization, under various acidic and alkaline conditions. Enzymatic hydrolysis, employing commercial enzymes at optimal temperature, pH, and enzyme-substrate ratios, produced distinct fractions according to molecular weight. Pepsin demonstrated the highest hydrolysis rate, with the fraction above 10kDa identified as the most bioactive hydrolysate. Antioxidant activity was evaluated through DPPH, ABTS, ferrous ion chelation, and reducing power assays, demonstrating high antioxidant potential and the ability to mitigate oxidative stress. The 10kDa fraction of pepsin hydrolysate exhibited 82.6% DPPH activity, 77.5% ABTS activity, 88.4% ferrous ion chelation activity, and higher reducing power potential (0.84 absorbance at 700nm). Further exploration of mechanisms, amino acid profiles, and potential in vivo benefits is essential to fully exploit the medicinal potential of these algae-derived hydrolysates.

Sustainable and one-pot fabrication of peptide chelated calcium from fish scale hydrolysates

Fish scales, considered as low-value by-products, contain peptides and hydroxyapatite that can be applied to produce peptide chelated calcium directly. This study developed a sustainable and one-pot fabrication method for the peptide-chelated calcium from fish scale hydrolysates (FSP-Ca). During pepsin hydrolysis, the releases of peptides (FSP), calcium, and phosphate from fish scales occurred simultaneously, and the chelation was also effectively performed. After a 6-h hydrolysis, the yield of FSP was 46.18%, and the dissolution rate of calcium was 49.53%. Under the optimal conditions (pH 7, chelation time of 25 min, and chelation temperature of 48 °C), a high chelation rate of 86.16% was obtained, with a calcium content of 81.8 mg/g. The results of UV absorption, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) confirmed the successful chelation between FSP and calcium derived from fish scales. The –NH2, –COO–, N–H, C=O, C–H, and –OH groups in FSP participated in the formation of FSP-Ca.Graphical

Investigation of functional, antioxidant, anti-inflammatory, and antidiabetic properties of legume seed protein hydrolysates

Plant-derived hydrolysates are emerging as promising agents in the management of diverse ailments due to their ensuing functional and bioactive properties. This study investigated the functional, antioxidant, anti-inflammatory, and antidiabetic properties of hydrolysates from Erythrina senegalensis and Vigna subtenarrea seeds. Crude proteins were isolated via alkaline solubilization, followed by acid precipitation to the isoelectric point. Respective protein isolates were hydrolyzed using trypsin and pepsin at an enzyme-substrate ratio of 1:8 (v/v) for 1–9 h. Pepsin hydrolysates after 9 h elicited the highest solubilities of 95.54 % and 94.24 % at pH 13, while, pepsin and trypsin hydrolysates of E. senegalensis digested for 1 and 9 h displayed the highest 1,1-diphenyl-2-picrylhydrazyl radical-scavenging (10-IC50 = 2.959 mg/mL) and total antioxidant capacity (7.243 mgAAE/g), respectively. Correspondingly, pepsin and trypsin hydrolysates of E. senegalensis hydrolyzed for 5 h demonstrated the most potent anti-inflammatory activities by cogently inhibiting xanthine oxidase and lipoxygenase activities with IC50 of 0.161 ± 0.111 and 0.018 ± 0.011 mg/mL, respectively. Trypsin hydrolysates of V. subterranea hydrolyzed for 5 h potently inhibited the activities of α-amylase and α-glucosidase with respective IC50 of 0.297 ± 0.060 and 0.314 ± 0.064 mg/mL. Overall, pepsin and trypsin hydrolysates of E. senegalensis demonstrated pronounced functional bioactivities relative to V. subterranea hydrolysates. This study concludes that both seeds could serve as unique matrices of potential functional bioactive peptides with prospects for managing diabetes.

Pepsin Hydrolysate from Surimi Industry-Related Olive Flounder Head Byproducts Attenuates LPS-Induced Inflammation and Oxidative Stress in RAW 264.7 Macrophages and In Vivo Zebrafish Model.

Fish head byproducts derived from surimi processing contribute about 15% of the total body weight, which are beneficial to health because they contain essential nutrients. In this study, olive flounder (OF) was the target species in order to maximize the byproduct utilization. In RAW 264.7 macrophages, the seven hydrolysates from OF head byproducts were examined for their inhibitory potential against inflammation and the oxidative stress induced by lipopolysaccharides (LPS). The pepsin hydrolysate (OFH-PH) demonstrated strong anti-inflammatory activity via the down-regulation of NO production, with an IC50 value of 299.82 ± 4.18 µg/mL. We evaluated the inhibitory potential of pro-inflammatory cytokines and PGE2 to confirm these findings. Additionally, iNOS and COX-2 protein expressions were confirmed using western blotting. Furthermore, the results from the in vivo zebrafish model demonstrated that OFH-PH decreased the LPS-elevated heart rate, NO production, cell death, and intracellular ROS level, while increasing the survival percentage. Hence, the obtained results of this study serve as a platform for future research and provide insight into the mediation of inflammatory disorders. These results suggest that OFH-PH has the potential to be utilized as a nutraceutical and functional food ingredient.

Zein/hyaluronic acid nanoparticle stabilized Pickering emulsion for astaxanthin encapsulation

Pickering emulsions have attracted considerable attention owing to the stability and functionality. In this study, zein/hyaluronic acid (ZH) nanoparticles were prepared and applied for stabilizing astaxanthin encapsulated Pickering emulsions. By non-covalent interaction between Zein and hyaluronic acid (HA), the conformation of zein changed and therefore improved the wettability of ZH nanoparticles. Unlike the spherical zein nanoparticles, ZH nanoparticles possessed a cross-linked structure with rough surface. Confocal laser scanning microscopy indicated that the nanoparticles accumulated at the oil-water interface. The Pickering emulsion stabilized by ZH nanoparticles exhibited high viscoelasticity and a solid-like behavior, as well as excellent stability during the storage. In vitro digestion results revealed that the presence of HA coating prevented the emulsion from pepsin hydrolysis and achieved efficient delivery of astaxanthin. This work confirmed that Pickering emulsion stabilized by ZH nanoparticles could be used as an effective deliver system for bioactive substances.

Prediction of antimicrobial activity of a food peptide and evaluation of its effectiveness in vitro

Food antimicrobial peptides are increasingly relevant in the treatment of bacterial infections and have a number of advantages in comparison with drugs: slower emergence of resistance in bacterial strains, high activity against antibiotic films and immunomodulatory properties. The physico-chemical properties causing antimicrobial properties include: cationic charge, hydrophobicity, molecular weight and amino acid sequence. Promising sources of antimicrobial peptides are milk proteins, in particular, cow colostrum proteins. The aim of the work is to extract a peptide from the pepsin hydrolysate of cow colostrum, predict its antimicrobial activity using a bioinformatic approach and confirm its effectiveness in vitro. The molecular mass distribution of the peptide was evaluated by mass spectrometric method. The analysis of mass spectra was carried out using the Mascot program, the Peptide Fingerprint option – using the Protein NCBI database. Microsequencing was performed using a MiSeq sequencer. Modeling of the spatial structure of the isolated peptide was carried out using the Schrodinger Maestro molecular modeling program. The antimicrobial activity of the peptide was studied by the disco-diffusion method on gram-positive and gram-negative bacteria. The peptide has been isolated from the pepsin hydrolysate of cow colostrum, which is absent in the known proteomic bases Protein NCBI and AVPdb and, accordingly, its biological activity and functions have not been studied. The resulting peptide belongs to linear alpha-helical peptides consists of 11 amino acid sequences ANRKLRANKSR with a molecular weight of 8.2 kDa, an isoelectric point at 12.79, a charge of +5 (cationic), hydrophilicity (hydrophobicity) +20.84 Kcal*mol-1. As a result of in vitro studies, it was found that the isolated peptide has antimicrobial activity against E. coli ATCC 25922 and B. subtilis and antimicrobial action against C. albicans.

Peptidomics Analysis of Soy Protein Hydrolysates-Antioxidant Properties and Mechanism of their Inhibition of the Oxidation of Palm Olein during Frying Cycles.

This study determined for the first time the structure of the peptides (i.e., peptidomics) in soy protein hydrolysates and elucidated their effects on an oil's oxidative stability during frying cycles. The oil investigated was palm olein during 0, 4, 8, and 12 frying cycles of plantain banana chips. Proteins were extracted and hydrolyzed with two proteases. Trypsin hydrolysate (HTRY) exhibited higher anti-radical activity (DPPH, 70.2%) than the control (unhydrolyzed proteins, 33.49%) and pepsin hydrolysate (HPEP, 46.1%) at 200 µg/mL. HPEP however showed a 4.6-fold greater reduction of ferric ions (FRAP) while also possessing a higher peroxyl radical scavenging ability (716 ± 30 µM Trolox Eq/g) than HTRY (38.5 ± 35 µM Trolox Eq/g). During oil oxidative stability tests, HPEP improved the oxidative stability of the palm olein oil after 8 and 12 frying cycles, characterized by lower concentrations of hydroperoxides, and carbonyl and volatile compounds. HTRY however exerteda pro-oxidant activity. Structural data from SDS-PAGE and tandem mass spectrometry showed that the mechanism for the greater activity of the pepsin hydrolysate occurred due to unique structural features and a higher percentage of short-chain peptides. This was justified by a 25, 31, and 48% higher contents of tryptophan, histidine, and methionine, respectively (important amino acids with hydrogen atom transfer and electron-donating capacities) in the peptides identified in the pepsin hydrolysate.

Preparation of Nanoemulsions with Low-Molecular-Weight Collagen Peptides from Sturgeon Fish Skin and Evaluation of Anti-Diabetic and Wound-Healing Effects in Mice.

This study aims to isolate collagen peptides from waste sturgeon fish skin, and prepare nanoemulsions for studying their anti-diabetic and wound-healing effects in mice. Collagen peptides were extracted and purified by acetic acid with sonication, followed by two-stage hydrolysis with 0.1% pepsin and 5% flavourzyme, and ultrafiltration with 500 Da molecular weight (MW) cut-off dialysis membrane. Animal experiments were performed with collagen peptides obtained by pepsin hydrolysis (37 kDa) and pepsin plus flavourzyme hydrolysis (728 Da) as well as their nanoemulsions prepared at two different doses (100 and 300 mg/kg/day). The mean particle size of low-MW and low-dose nanoemulsion, low-MW and high-dose nanoemulsion, high-MW and low-dose nanoemulsion and high-MW and high-dose nanoemulsion was, respectively, 16.9, 15.3, 28.1 and 24.2 nm, the polydispersity index was 0.198, 0.215, 0.231 and 0.222 and zeta potential was -61.2, -63.0, -41.4 and -42.7 mV. These nanoemulsions were highly stable over a 90-day storage period (4 °C and 25 °C) and heating at 40-100 °C (0.5-2 h). Experiments in mice revealed that the low-MW and high-dose nanoemulsion was the most effective in decreasing fasting blood glucose (46.75%) and increasing wound-healing area (95.53%). Collectively, the sturgeon fish skin collagen peptide-based nanoemulsion is promising for development into a health food or wound-healing drug.

In vitro apoptotic activity of Lablab purpureus (L.) Sweet low-molecular-weight peptides

Cancer prevalence is a rapidly growing concern globally. Traditional treatment protocols, radiotherapy, and chemotherapy are associated with adverse side effects on the human body. Therefore, there is a need for alternative therapies. Peptides from leguminous protein are known for exhibiting positive biological activity that could target cancer cells and minimize side effects. This study assessed the apoptotic ability of peptide fractions 2. The fraction was derived from the pepsin hydrolysate of Lablab purpureus that was fractionated by ultrafiltration and subsequently by reverse-phase high-pressure liquid chromatography. The markers of apoptosis (caspase-9 and -3, p53, and annexin V-PI) were then observed for efficacy. Caspase-9 and -3 showed activity to a greater degree in cancerous cell line A549 (2.3-fold and 1.1-fold) and MCF-7 (2.7-fold and 1.8-fold), respectively, compared to camptothecin (positive control). Expression of p53 on treated cancerous cell lines (A549 and MCF-7) demonstrated greater ability over the non-cancerous cell line (HEK293) with A549 showing the highest activity at 29.923 µg/mL. Finally, annexin V-PI staining sorted cells into phases of apoptosis. Treated A549 and MCF-7 cells detected 85.4% and 89.6% of cells undergoing apoptosis. Overall, Fraction 2 triggered apoptosis in cancer cell lines while minimally harming non-cancerous cells.

Effect of pH and protein composition on proteolysis of goat milk proteins by pepsin and pancreatin

The roles of protein composition, pH and enzymes in goat milk protein hydrolysis is still unclear and the proteolysis of low abundant goat milk proteins has received limited attention. The aim of this study was to study the impact of protein composition and proteolytic conditions on goat milk protein hydrolysis in a simplified digestion model. Both whole milk and infant formula were hydrolyzed at pH 2 and 4, using pepsin as well as pepsin combined with pancreatin. Intact proteins were separated from digests using spin filters, followed by bottom-up proteomics of the separated proteins. Results show that under all conditions, caseins are hydrolyzed quickly. Goat casein hydrolysis in infant formula was slightly faster than in goat whole milk, possibly due to less casein coagulation during pepsin hydrolysis at both pH 2 and 4. Several low abundant immunoactive goat milk proteins, especially immunoglobulins, GLYCAM-1 and osteopontin, resisted proteolysis more than high abundant proteins, independent of the pH and enzyme used for hydrolysis. Fast hydrolysis of casein and slow hydrolysis of immunoactive proteins may indicate a good balance between protein utilization and protection of the infant by goat milk proteins.

Identification of potent antioxidant bioactive peptides from the soluble proteins of chicken egg yolk

Background: Eggs are an excellent nutrient-dense food containing proteins, fats, carbohydrates, minerals, and vitamins. While many proteins are present in egg yolk, there arefew studies on their health benefits. Objective: The aim of this study was to explore the antioxidant peptides derived from the soluble protein fractions of egg yolk. Lipids and lipoproteins were removed with activated carbon and centrifugation after water dilution at acidic pH. Materials and Methods: Compared with 3.6 grams of protein in egg white, egg yolk contains 2.7 grams of protein in a single large egg. The egg yolk soluble protein (EYsP) was digested with pepsin for 2h at pH 3.0 (P-EYsP), followed by digestion with trypsin (P-EYsP-T), α-chymotrypsin (P-EYsP-α), or both enzymes (P-EYsP-T/α). The most active digest was fractionated using sephacryl S-100 gel filtration, followed by reversed phase-HPLC of the most active fraction. The antioxidant activities were evaluated using a superoxide anion-generating system of xanthine oxidase, DPPH-scavenging assay, and yeast cells as an oxidative-stress tolerance cellular model. Results: The intact proteins (EYsP) showed antioxidant activity, but pepsin hydrolysate (P-EYsP) exhibited greater superoxide-scavenging activities than EYsP, while P-EYsP-T, P-EYsP-α and P-EYsP-T/α lacked activities. The P-EYsP and its subsequent proteases (P-EYsP-T, P-EYsP-α and P-EYsP-T/α) exhibited significant DPPH reduction, but P-EYsP-T, P-EYsP-α and P-EYsP-T/α exhibited the strongest DPPH reduction activities. MALDI-TOF-MS analysis revealed five major antioxidant peptides, two derived from yolk glycoprotein 40 (859 Da, 883Da), two from lipovitelline (901Da, 945 Da), and one from livetin (1089 Da). The peptides exhibited potent superoxide anion as well as DPPH scavenging activities and markedly enhanced the tolerance of yeast cells against peroxide-induced oxidative stress.Conclusion: The results show that these bioactive peptides hold a fascinating opportunity for their potential as nutraceuticals in prevention and combating oxidative stress-associated diseases.Keywords: Egg yolk proteins; bioactive peptides; antioxidant; superoxide-scavenging; DPPH-reduction; yeast tolerance

The determination of epidermal growth factor in Edible bird's nest by enzyme-linked immunosorbent assay

Edible bird's nest (EBN) is a traditional food which was nourishing and functional. Particularly, there is the epidermal growth factor (EGF) in EBN, which is thought to play an important role in promoting skin repair. However, the type and content of EGF in EBN were not determined yet. In this study, the type of EGF in EBN was identified as bird EGF by enzyme-linked immunosorbent assay and this method was validated to be accurate and precise. Moreover, it was found that the content of EGF in raw-unclean EBN, raw-clean EBN and stewed EBN was 3000 pg/g–4000 pg/g and there were no significant differences, which suggested that the batches, origins, forms, stewing temperatures and stewing times of EBN had no effect on the content of EGF in EBN. However, it was due to that enzyme destroyed the primary structure of EGF, the EGF content of neutral protease and trypsin hydrolysates of EBN was lower than that of flavor enzymes, alkaline protease and pepsin hydrolysates of EGF. This study was the first to determine the type and content of EGF in EBN, and provided a theoretical basis for the selection and processing of EBN and using EBN as a source of EGF.

Antibacterial Effect of Shrimp By-Products Hydrolysate on Specific Spoilage Organisms of Squid.

In order to further develop and utilize shrimp processing by-products, in this study, a novel antibacterial hydrolysate of shrimp by-products by pepsin hydrolysis (SPH) was prepared. The antibacterial effect of SPH on specific spoilage organisms of squid after end storage at room temperature (SE-SSOs) was investigated. SPH showed an antibacterial effect on the growth of SE-SSOs, with (23.4 ± 0.2) mm of inhibition zone diameter. The cell permeability of SE-SSOs was enhanced after SPH treatment for 12 h. Some bacteria were twisted and shrunk, while pits and pores formed and intracellular contents leaked under scanning electron microscopy observation. The flora diversity of SE-SSOs treated with SPH was determined by a 16S rDNA sequencing technique. Results showed that SE-SSOs were mainly composed of the phyla of Firmicutes and Proteobacteria, among which Paraclostridium (47.29%) and Enterobacter (38.35%) were dominant genera. SPH treatment resulted in a significant reduction in the relative abundance of the genus Paraclostridium and increased the abundance of Enterococcus. Linear discriminant analysis (LDA) of LEfSe conveyed that SPH treatment had a significant impact on altering the bacterial structure of SE-SSOs. The 16S PICRUSt of Cluster of Orthologous Group (COG) annotation revealed that SPH treatment for 12 h could significantly increase the function of transcription level [K], while SPH treatment for 24 h could downregulate post-translational modifications, protein turnover, and chaperone metabolism functions [O]. In conclusion, SPH has a proper antibacterial effect on SE-SSOs and can change the flora structure of SE-SSOs. These findings will provide a technical basis for the development of inhibitors of squid SSOs.