Antioxidant activity of peptides derived from egg white proteins by enzymatic hydrolysis

Green guaje (Leucaena leucocephala) and pigmented guaje (Leucaena esculenta) as sources of antioxidant and immunomodulatory peptides

In recent years, there has been a growing interest in plant-based diets, particularly legumes, as a sustainable and healthy dietary choice. This study breaks new ground by investigating the effects of simulated gastrointestinal digestion on green (Leucaena leucocephala) and pigmented (Leucaena esculenta) guaje proteins. We evaluated the antioxidant and immunomodulatory properties of ultrafiltered fractions resulting from digestion in a macrophage model. Both fractions showed promising potential as radical scavengers. The fraction <5 kDa from pigmented guaje, even at the lowest doses tested, significantly (p < 0.05) inhibited the release of pro-inflammatory cytokines TNF-α and IL-6, and demonstrated an immunomodulatory effect by reducing the levels of ROS and NO. These findings suggest that green and pigmented guaje could be a valuable source of bioactive peptides, potentially used as a coadjutant for treating and preventing oxidative stress and inflammation-associated non-communicable diseases through the utilization of underutilized legumes.

Identification of novel saltiness/saltiness enhancing peptides in egg proteins: Molecular docking, action mechanism and in vitro activity validation

In this study, novel saltiness/saltiness enhancing peptides VESQTNGIIR, NQITKPNDVY, and DEDTQAMP were identified from the hen egg proteins via virtual enzymatic, molecular docking, and electronic tongue analysis. Their saltiness enhancement effect was analyzed by e-tongue analysis. Saltiness enhancement rates of saltiness peptide VESQTNGIIR were 47.24 %, 95.28 % and 105.94 %, and those of the saltiness peptide NQITKPNDVY were 32.40 %, 70.16 %, and 71.25 % at the salt reduction concentrations of 25 %, 35 % and 45 %, respectively. Saltiness enhancement rates of saltiness enhancing peptide DEDTQAMP were 5.83 % and 11.24 % at 25 % and 35 % salt reduction concentrations, respectively. Molecular docking demonstrated that Glu286, Arg330, Arg424, and Arg583 may be the key amino acids interacting with TMC4, whereas that carbon hydrogen bond, conventional hydrogen bond, and attractive charge interactions were important forces in peptides-TMC interactions. The study indicated that the peptides VESQTNGIIR and NQITKPNDVY may be ideal saltiness/saltiness enhancing peptides.

Feasibility analysis on the application of the Maillard reaction in developing Lentinula edodes umami seasoning: Based on the umami substances, sensory quality, physicochemical properties of the products

To elucidate the feasibility of applying the Maillard reaction (MR) to the development of Lentinula edodes umami seasoning, this study quantitatively analyzed the main umami substances in the products and evaluated their sensory quality. Simultaneously, the rheology, thermal stability, zeta potential, and particle size of the products were also studied. The results indicated that after the MR, the content of umami amino acids in Lentinula edodes hydrolysates (LEHs) decreased from 17.72 mg/g to 12.70 mg/g, while the content of umami nucleotides increased from 0.61 mg/g to 1.36 mg/g. The equivalent umami concentration of MR products was high, at 293.84 ± 11.05 g MSG/100 g. Taste activity value indicated that 5'-GMP, Asp, and Glu were the key umami substances. MR increased the umami sensory score, particle size, absolute zeta potential, and viscosity of LEHs, and altered their thermal stability. These results support the application of MR in the mushroom umami seasoning.

Effects of vegetative propagation on protein content and bioactivity of the red seaweed Palmaria palmata

Production of the red seaweed Palmaria palmata is currently hindered by a lack of standardised cultivation methods leading to uncertainties in yield and product quality. This study assessed vegetative propagation of meristematic fragments and the protein content and bioactivity potential of resulting plants. Growth was strong and sustained, averaging 5% day-1. Total protein contents initially decreased but recovered as the fragments grew larger and thicker. Samples displayed the highest antioxidant activity early in the experiment, suggesting that wounds may increase the secretion of antioxidant compounds. In silico analysis identified 762 potentially bioactive motifs, including 70 matching in vitro results. The newly discovered peptide SLLYSDITRPGGNMYTTR (SR18), linked to the pigment allophycocyanin, had very strong antioxidant properties and may drive the recorded in vitro activity. Vegetative propagation appears as a strong potential cultivation tool, and the utilised approach can be applied to assess the cultivation and nutritional potential of other seaweed species.

Egg White Hydrolysate Mitigates Cadmium-induced Neurological Disorders and Oxidative Damage

We aimed to investigate whether the consumption of Egg White Hydrolysate (EWH) acts on nervous system disorders induced by exposure to Cadmium (Cd) in rats. Male Wistar rats were divided into (a) Control (Ct): H2O by gavage for 28 days + H2O (i.p. - 15th - 28th day); (b) Cadmium (Cd): H2O by gavage + CdCl2 - 1 mg/kg/day (i.p. - 15th - 28th day); (c) EWH 14d: EWH 1 g/kg/day by gavage for 14 days + H2O (i.p.- 15th - 28th day); (d) Cd + EWH cotreatment (Cd + EWHco): CdCl2 + EWH for 14 days; (e) EWH 28d: EWH for 28 days; (f) EWHpre + Cd: EWH (1st - 28th day) + CdCl2 (15th - 28th day). At the beginning and the end of treatment, neuromotor performance (Neurological Deficit Scale); motor function (Rota-Rod test); ability to move and explore (Open Field test); thermal sensitivity (Hot Plate test); and state of anxiety (Elevated Maze test) were tested. The antioxidant status in the cerebral cortex and the striatum were biochemically analyzed. Cd induces anxiety, and neuromotor, and thermal sensitivity deficits. EWH consumption prevented anxiety, neuromotor deficits, and alterations in thermal sensitivity, avoiding neuromotor deficits both when the administration was performed before or during Cd exposure. Both modes of administration reduced the levels of reactive species, and the lipid peroxidation increased by Cd and improved the striatum's antioxidant capacity. Pretreatment proved to be beneficial in preventing the reduction of SOD activity in the cortex. EWH could be used as a functional food with antioxidant properties capable of preventing neurological damage induced by Cd.

Protein Hydrolysates from Fishery Processing By-Products: Production, Characteristics, Food Applications, and Challenges

Fish processing by-products such as frames, trimmings, and viscera of commercial fish species are rich in proteins. Thus, they could potentially be an economical source of proteins that may be used to obtain bioactive peptides and functional protein hydrolysates for the food and nutraceutical industries. The structure, composition, and biological activities of peptides and hydrolysates depend on the freshness and the actual composition of the material. Peptides isolated from fishery by-products showed antioxidant activity. Changes in hydrolysis parameters changed the sequence and properties of the peptides and determined their physiological functions. The optimization of the value of such peptides and the production costs must be considered for each particular source of marine by-products and for their specific food applications. This review will discuss the functional properties of fishery by-products prepared using hydrolysis and their potential food applications. It also reviews the structure-activity relationships of the antioxidant activity of peptides as well as challenges to the use of fishery by-products for protein hydrolysate production.

Silk Fibroin Improves the Biological Properties of Egg White-Based Bioink for the Bioprinting of Tissue Engineering Materials

Egg white (EW) is a common nutritious food with excellent heat gelation and biocompatibility, but its application in biomaterials is considerably limited. Silk fibroin (SF) is a protein-based fiber with both excellent mechanical properties and biocompatibility, and its application in biomaterials has attracted much attention. Here, the EW/SF composite scaffold was first synthesized with GMA-modified EW/SF composite bioink (G-EW/SF). When homogenized EW and SF were individually grafted with glycidyl methacrylate (GMA), the grafted EW (G-EW) and SF (G-SF) were mixed in different proportions and then added to I2959. The resulting G-EW/SF composite bioink could be bioprinted into various EW/SF composite scaffolds. Among them, the compressive modulus of EW/SF (50%) composite scaffolds incorporating 50% G-SF was significantly improved. It had a three-dimensional (3D) polypore structure with an average pore size of 61 μm and was mainly composed of β-sheet structures. Compared with the EW scaffold alone, the thermal decomposition temperature of the EW/SF scaffold was 10 °C higher, and the residual rate after 9 days of enzymatic hydrolysis had increased by about 18%. The scaffold prolonged the sustained release of insulin and promoted the adhesion, growth, and proliferation of the L-929 cells. Therefore, the EW/SF composite scaffolds with good cell proliferation ability and certain mechanical properties can be used in different applications including cells, drugs, and tissues. These results provide new prospects for the application of the EW protein to medical tissue engineering materials.

The effect of theabrownins on the amino acid composition and antioxidant properties of hen eggs

Pu-erh tea theabrownins (TBs) exert beneficial effect on egg quality and antioxidant properties of eggs, but the underlying mechanisms behind this response are unclear. In this study, we investigate the effect of TBs on egg antioxidative activity, amino acid and fatty acid profiles, and the underlying relationship between the TBs and oxidant-sensitive Nrf2 signaling pathway in laying hens. Eighty layers were fed a basal diet (control) and 400 mg/kg of TBs supplemented diet for 12 wk. TBs led to an increase in albumen height and Haugh unit (P < 0.05). The albumen lysine, valine, and tryptophan were higher in layers fed TBs, whereas yolk tryptophan, methionine, vitamin A, and α-tocopherol content were enhanced by TBs (P < 0.05). Eggs albumen and yolk showed higher total antioxidant capacity (T-AOC), reducing power (RP), and the scavenging rate of 2,2-diphenyl-1-picrylhydrazyl hydrate (DPPH), and lower MDA content than those of eggs from the control group (P < 0.05). Also, magnum Nrf2, hemeoxygenase 1 (HO-1), NAD(P)H quinone dehydrogenase 1 (NQO1), and Bcl2 expression were up-regulated by TBs, whereas magnum proapoptotic gene (Bax, caspase 3, Cyt C) were down-regulated by TBs (P < 0.05). Our findings suggest that TBs improved egg albumen quality and antioxidant activity, and the Nrf2-ARE pathway were found to be involved in this process.

Absorption of egg white hydrolysate in the intestine: Clathrin-dependent endocytosis as the main transport route

This paper aimed to investigate the in vivo absorption of egg white hydrolysate (EWH) in rats and the transport route across the intestinal epithelium. Results showed that the level of plasma peptide-bound amino acid (PAA) of the EWH-supplemented rats (EWH-R) was determined to be 2012.18 ± 300.98 μmol/L, 10.72% higher than that of the control group, and was significantly positively correlated to that of EWH. Thirty-three egg white-derived peptides were successfully identified from the plasma of EWH-R, and 20 of them were found in both EWH-R plasma and EWH, indicating that these peptides tend to be absorbed through the intestinal epithelium in intact forms into the blood circulation. In addition, 637 up-regulated and 577 down-regulated genes in Caco-2 cells incubated with EWH were detected by RNA-sequencing and the clathrin-dependent endocytosis was the most enriched pathway in KEGG analysis. EWH significantly increased the mRNA levels of the key genes involved in the clathrin-dependent endocytosis but these changes would be inhibited by the clathrin-dependent endocytosis inhibitor of chlorpromazine. Moreover, the transepithelial transport of EWH across Caco-2 cell monolayers was significantly reduced by chlorpromazine. This study provided molecular-level evidence for the first time that clathrin-dependent endocytosis might be the main transport route of EWH in the intestinal epithelium.

Investigation of the effects of bovine collagen peptides and mixed berries on rheological properties and biological activity of egg white-based beverage via central composite design

Modern consumer expectations have become highly diversified: they want more opportunities to meet diverse family needs (diversity of family members in age, gender, physical activity, etc. ,) and individual health goals with a huge variety of sensorial preferences. Our research is aimed to develop a protein-dense, highly bioactive, lactose- and whey protein-free beverage applying a central composite rotational design (CCRD) with 2 factors. For this purpose, an egg white-based beverage was flavored with mixed berries (factor A) and enriched with bovine collagen peptides (factor B). After suitable sample preparation, the rheological properties were investigated by an Anton Paar MCR 92 rheometer (with CC 27 system, and flow behavior was analyzed with a Herschel-Bulkley (H-B) model). The antioxidant capacity of samples was investigated by Ferric Reducing Antioxidant Power (FRAP) method, the total anthocyanin content was estimated based on a spectrophotometric method, and the total phenolic content was determined by the Folin Ciocalteu method. Our results are figured on response surfaces demonstrating that both factors and their interactions show a positive correlation with the examined parameters. Based on the CCRD, all investigated parameters are significantly influenced by at least one aspect and can be adequately estimated for further product development.

Dietary Egg White Hydrolysate Prevents Male Reproductive Dysfunction after Long-Term Exposure to Aluminum in Rats

Aluminum (Al) is a non-essential metal omnipresent in human life and is considered an environmental toxicant. Al increases reactive oxygen production and triggers immune responses, contributing to chronic systemic inflammation development. Here, we have tested whether an egg white hydrolysate (EWH) with potential bioactive properties can protect against changes in reproductive function in rats exposed to long-term Al dietary levels at high and low doses. Male Wistar rats received orally: low aluminum level group-AlCl₃ at 8.3 mg/kg b.w. for 60 days with or without EWH (1 g/kg/day); high aluminum level group-AlCl₃ at 100 mg/kg b.w. for 42 days with or without EWH (1 g/kg/day). The co-administration of EWH prevented the increased Al deposition surrounding the germinative cells, reducing inflammation and oxidative stress in the reproductive organs. Furthermore, the daily supplementation with EWH maintained sperm production and sperm quality similar to those found in control animals, even after Al exposure at a high dietary contamination level. Altogether, our results suggest that EWH could be used as a protective agent against impairment in the reproductive system produced after long-term exposure to Al at low or high human dietary levels.

Antioxidant Properties of Hemp Proteins: From Functional Food to Phytotherapy and Beyond

As one of the oldest plants cultivated by humans, hemp used to be banned in the United States but returned as a legal crop in 2018. Since then, the United States has become the leading hemp producer in the world. Currently, hemp attracts increasing attention from consumers and scientists as hemp products provide a wide spectrum of potential functions. Particularly, bioactive peptides derived from hemp proteins have been proven to be strong antioxidants, which is an extremely hot research topic in recent years. However, some controversial disputes and unknown issues are still underway to be explored and verified in the aspects of technique, methodology, characteristic, mechanism, application, caution, etc. Therefore, this review focusing on the antioxidant properties of hemp proteins is necessary to discuss the multiple critical issues, including in vitro structure-modifying techniques and antioxidant assays, structure-activity relationships of antioxidant peptides, pre-clinical studies on hemp proteins and pathogenesis-related molecular mechanisms, usage and potential hazard, and novel advanced techniques involving bioinformatics methodology (QSAR, PPI, GO, KEGG), proteomic analysis, and genomics analysis, etc. Taken together, the antioxidant potential of hemp proteins may provide both functional food benefits and phytotherapy efficacy to human health.

Genetic resilience in chickens against bacterial, viral and protozoal pathogens

The genome contributes to the uniqueness of an individual breed, and enables distinctive characteristics to be passed from one generation to the next. The allelic heterogeneity of a certain breed results in a different response to a pathogen with different genomic expression. Disease resistance in chicken is a polygenic trait that involves different genes that confer resistance against pathogens. Such resistance also involves major histocompatibility (MHC) molecules, immunoglobulins, cytokines, interleukins, T and B cells, and CD4+ and CD8+ T lymphocytes, which are involved in host protection. The MHC is associated with antigen presentation, antibody production, and cytokine stimulation, which highlight its role in disease resistance. The natural resistance-associated macrophage protein 1 (Nramp-1), interferon (IFN), myxovirus-resistance gene, myeloid differentiation primary response 88 (MyD88), receptor-interacting serine/threonine kinase 2 (RIP2), and heterophile cells are involved in disease resistance and susceptibility of chicken. Studies related to disease resistance genetics, epigenetics, and quantitative trait loci would enable the identification of resistance markers and the development of disease resistance breeds. Microbial infections are responsible for significant outbreaks and have blighted the poultry industry. Breeding disease-resistant chicken strains may be helpful in tackling pathogens and increasing the current understanding on host genetics in the fight against communicable diseases. Advanced technologies, such as the CRISPR/Cas9 system, whole genome sequencing, RNA sequencing, and high-density single nucleotide polymorphism (SNP) genotyping, aid the development of resistant breeds, which would significantly decrease the use of antibiotics and vaccination in poultry. In this review, we aimed to reveal the recent genetic basis of infection and genomic modification that increase resistance against different pathogens in chickens.

From Small Peptides to Large Proteins against Alzheimer’sDisease

Alzheimer’s disease (AD) is the most common neurodegenerative disorder in the elderly. The two cardinal neuropathological hallmarks of AD are the senile plaques, which are extracellular deposits mainly constituted by beta-amyloids, and neurofibrillary tangles formed by abnormally phosphorylated Tau (p-Tau) located in the cytoplasm of neurons. Although the research has made relevant progress in the management of the disease, the treatment is still lacking. Only symptomatic medications exist for the disease, and, in the meantime, laboratories worldwide are investigating disease-modifying treatments for AD. In the present review, results centered on the use of peptides of different sizes involved in AD are presented.

Antioxidant and immunomodulatory potency of Lacticaseibacillus rhamnosus NCDC24 fermented milk-derived peptides: A computationally guided in-vitro and ex-vivo investigation

Infections of microbial and non-microbial origins have been associated with significant immunological manifestations, thereby underscoring the need for a thorough understanding and investigation of novel immunomodulatory and antioxidant molecules that could prevent these incidences. To this end, we herein aim to identify fermented milk peptides with antioxidant and immunomodulatory properties that could be exploited for specific future applications. Our computational prediction models indicate that these peptides are non-toxic and possess considerable hydrophobicity (19.82-38.96 %) and functionality. Further analyses reveal that two of the four peptides, i.e., Pep 1 (AGWNIPM) and Pep 4 (YLGYLEQLLR), possess higher in-vitro antioxidant activity. The immunomodulatory potential of these two peptides (Pep 1 and Pep 4) is further demonstrated by using a combination of molecular simulation trajectory and ex-vivo approaches. Both peptides demonstrate ability to control the production of pro- inflammatory (TNF-α, IL-1, and IL-6) and anti-inflammatory (IL-10) cytokines as well as nitric oxide release in LPS-stimulated murine peritoneal macrophages. Similarly, peptide interferences also lead to significant (P < 0.05) improvement in macrophage phagocytic capacity. Taken together, these findings highlight the antioxidant and immunomodulatory properties of fermented milk peptides (Pep 1 and Pep 4) within the cellular environment and should facilitate prospective studies exploring such bioactive peptides and related functional molecules mediating the benefits of fermented milk products on human health.

ROS Suppression by Egg White Hydrolysate in DOCA-Salt Rats—An Alternative Tool against Vascular Dysfunction in Severe Hypertension

This study aimed to evaluate the potential for lowering blood pressure and beneficial effects on mesenteric resistance arteries (MRA) and conductance vessels (aorta) produced by dietary supplementation of an egg white hydrolysate (EWH) in rats with severe hypertension induced by deoxycorticosterone plus salt treatment (DOCA-salt), as well as the underlying mechanisms involved. The DOCA-salt model presented higher blood pressure, which was significantly reduced by EWH. The impaired acetylcholine-induced relaxation and eNOS expression observed in MRA and aorta from DOCA-salt rats was ameliorated by EWH. This effect on vessels (MRA and aorta) was related to the antioxidant effect of EWH, since hydrolysate intake prevented the NF-κB/TNFα inflammatory pathway and NADPH oxidase-induced reactive oxygen species (ROS) generation, as well as the mitochondrial source of ROS in MRA. At the plasma level, EWH blocked the higher ROS and MDA generation by DOCA-salt treatment, without altering the antioxidant marker. In conclusion, EWH demonstrated an antihypertensive effect in a model of severe hypertension. This effect could be related to its endothelium-dependent vasodilator properties mediated by an ameliorated vessel’s redox imbalance and inflammatory state.

Bovine Bone Gelatin-Derived Peptides: Food Processing Characteristics and Evaluation of Antihypertensive and Antihyperlipidemic Activities

This study aimed to evaluate the food processing properties of bovine bone gelatin-derived peptides (BGPs) and their effects and mechanisms on hypertension and hypertension complications in spontaneously hypertensive rats (SHRs). BGPs had good acid, high temperature, and NaCl resistance abilities in vitro. Additionally, Maillard reaction of BGPs with low-dose reducing sugar (≤15%) exhibited a free radical scavenging effect. BGPs significantly reduced the blood pressure, triglyceride levels, and the low-density lipoprotein cholesterol/high-density lipoprotein cholesterol ratio in SHRs through downregulated angiotensin converting enzyme (ACE), angiotensin II (Ang II), and Ang II type 1 receptor (AT1R) levels and the upregulated Ang II type 2 receptor (AT2R) level. In brief, BGP could alleviate hypertension and dyslipidemia in SHRs by inhibiting ACE/Ang II/AT1R and activating the Ang II/AT2R signaling pathway. Our study suggests that BGP has good food processing properties and could be a potential nutraceutical for antihypertensive and antihyperlipidemic issues.

Health Functions of Egg Protein

Egg protein is a remarkably abundant source of protein, with an amino acid score of 100 and the highest net protein utilization rate. However, there have been relatively fewer studies investigating the health benefits of egg protein. In this review, we have summarized the available information regarding the health benefits of egg proteins based on human studies. In particular, studies conducted on the characteristics of egg whites, as they are high in pure protein, have reported their various health functions, such as increases in muscle mass and strength enhancement, lowering of cholesterol, and visceral fat reduction. Moreover, to facilitate and encourage the use of egg white protein in future, we also discuss its health functions. These benefits were determined by developing an egg white hydrolysate and lactic-fermented egg whites, with the latter treatment simultaneously improving the egg flavor. The health benefits of the protein hydrolysates from the egg yolk (bone growth effect) and eggshell membrane (knee join pain-lowering effect) have been limited in animal studies. Therefore, the consumption of egg protein may contribute to the prevention of physical frailty and metabolic syndromes.

Effects of Inherent Lactic Acid Bacteria on Inhibition of Angiotensin I-Converting Enzyme and Antioxidant Activities in Dry-Cured Meat Products

The aim of this study was to investigate the inherent bacteria that contribute to expressing the angiotensin I-converting enzyme (ACE) inhibitory activity and the antioxidant activity of dry-cured meat products without a bacterial starter. Among the ten dry-cured meat product samples, Coppa and Milano salami exhibited high ACE inhibitory activity, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging ability, and oxygen radical absorbance capacity (ORAC). No consistent trend was observed in the pH values or the total peptide and imidazole dipeptide concentration of the products that exhibited high ACE inhibitory and antioxidant activities in the tested samples. To investigate the bacteria contributing to the ACE inhibitory and antioxidant activities of the product, 16S rRNA sequencing analysis, isolation, and identification of bacteria were performed using not only Coppa and Milano salami but also the Jamon Serrano and Parma prosciutto products that had low functional activities. Results suggest the Lactobacillales order, particularly the species Latilactobacillus sakei and Pediococcus pentosaceus, were the main inherent bacteria in Coppa and Milano salami, respectively, compared with the Jamon Serrano and Parma prosciutto products. Therefore, the inherent lactic acid bacteria in dry-cured meat products without bacterial starter is important for ACE inhibitory and antioxidant activities of the products.

Antioxidant capacity and identification of radical scavenging peptides from Crema de Chiapas, Fresco and Cocido cheeses

Bioactive peptides may positively impact bodily functions. One of these are the antioxidant peptides which are well documented for a wide variety of food matrices, mostly from plant sources. Nevertheless, information of antioxidant milk-derived peptides is still a little-known field. The present study was aimed to evaluating the antioxidant capacity (AC) in vitro of water soluble extracts < 3 kDa (WSE) from three artisanal Mexican cheeses: Crema de Chiapas (CrC), Fresco (FC) and Cocido (CC). This study was carried out for cheeses of different days of storage (0, 5, 10, 15, and 20) at 4 °C. AC was assayed to the respective WSE by 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) diamoniun salt (ABTS) and oxygen radical absorbance capacity (ORAC) methods and those WSE that showed the most antioxidant capacity from each cheese were analyzed by using RP-HPLC/MS to identify and characterize the novel specific peptides. All the WSE analyzed show antioxidant capacity, especially those from CrC and CC which display the highest AC at 15 days of storage. Regarding to WSE from FC, the AC was constant during storage. Identified structures reveal that these novel peptides possess high content of specific amino acids, mainly proline, valine, leucine and phenylalanine, of which it has already been shown antioxidant properties. This study demonstrate that these artisanal Mexican cheeses are sources of potential antioxidant peptides.

Graphic abstract

Natural Products of Plants and Animal Origin Improve Albumen Quality of Chicken Eggs

Albumen quality is recognized as one of the major yardsticks in measuring egg quality. The elasticity of thick albumen, a strong bond in the ovomucin-lysozyme complex, and excellent biological properties are indicators of high-quality albumen. The albumen quality prior to egg storage contribute to enhance egg’s shelf life and economic value. Evidence suggests that albumen quality can deteriorate due to changes in albumen structure, such as the degradation of β-ovomucin subunit and O-glyosidic bonds, the collapse of the ovomucin-lysozyme complex, and a decrease in albumen protein-protein interaction. Using organic minerals, natural plants and animal products with antioxidant and antimicrobial properties, high biological value, no residue effect and toxicity risk could improve albumen quality. These natural products (e.g., tea polyphenols, marigold extract, magnolol, essential oils, Upro (small peptide), yeast cell wall, Bacillus species, a purified amino acid from animal blood, and pumpkin seed meal) are bio-fortified into eggs, thus enhancing the biological and technological function of the albumen. Multiple strategies to meeting laying hens’ metabolic requirements and improvement in albumen quality are described in this review, including the use of amino acids, vitamins, minerals, essential oils, prebiotics, probiotics, organic trace elements, and phytogenic as feed additives. From this analysis, natural products can improve animal health and consequently albumen quality. Future research should focus on effects of these natural products in extending shelf life of the albumen during storage and at different storage conditions. Research in that direction may provide insight into albumen quality and its biological value in fresh and stored eggs.

Potential benefits of egg white hydrolysate in the prevention of Hg-induced dysfunction in adipose tissue

Aim: To investigate the effects of egg white hydrolysate (EWH) on the lipid and glycemic metabolism disruption in the white adipose tissue (WAT) dysfunction induced by mercury (Hg). Experimental: Wistar rats were treated for 60 days: control (saline, intramuscular - i.m.); hydrolysate (EWH, gavage, 1 g kg^-1 day^-1); mercury (HgCl₂, i.m., 1^st dose 4.6 μg kg^-1, subsequent doses 0.07 μg kg^-1 day^-1) and hydrolysate-mercury (EWH-HgCl₂). Hg level and histological analyses were performed in epididymal WAT (eWAT), pancreas and liver. GRP78, CHOP, PPARα, PPARγ, leptin, adiponectin, and CD11 mRNA expressions were analyzed in eWAT. The plasma lipid profile, glucose, and insulin levels were measured. Antioxidant status was also evaluated in the plasma and liver. Results: EWH intake prevented the reduced eWAT weight, adipocyte size, insulin levels, and antioxidant defenses and the increased glucose and triglyceride levels induced by Hg exposure; hepatic glutathione levels were higher in rats co-treated with EWH. The increased mRNA expression of CHOP, PPARα, and leptin induced by Hg was reduced in co-treated rats. EWH did not modify the elevated mRNA expression of GRP78, PPARγ and adiponectin in Hg-treated rats. Increased levels of Hg were found in the liver; the co-treatment did not alter this parameter. EWH prevented the morphological and metabolic disorder induced by Hg, by improving antioxidant defenses, inactivating pro-apoptotic pathways and normalizing the mRNA expression of PPARs and adipokines. Its effects enabled an increase in insulin levels and a normal balance between the fat storage and expenditure mechanisms in WAT. Conclusions: EWH may have potential benefits in the prevention and management of Hg-related metabolic disorders.

Bioactive Peptides: Synthesis, Sources, Applications, and Proposed Mechanisms of Action

Bioactive peptides are a group of biological molecules that are normally buried in the structure of parent proteins and become active after the cleavage of the proteins. Another group of peptides is actively produced and found in many microorganisms and the body of organisms. Today, many groups of bioactive peptides have been marketed chemically or recombinantly. This article reviews the various production methods and sources of these important/ubiquitous and useful biomolecules. Their applications, such as antimicrobial, antihypertensive, antioxidant activities, blood-lipid-lowering effect, opioid role, antiobesity, ability to bind minerals, antidiabetic, and antiaging effects, will be explored. The types of pathways proposed for bioactive applications will be in the next part of the article, and at the end, the future perspectives of bioactive peptides will be reviewed. Reading this article is recommended for researchers interested in various fields of physiology, microbiology, biochemistry, and nanotechnology and food industry professionals.

Antioxidant Stress and Anti-Inflammatory Activities of Egg White Proteins and Their Derived Peptides: A Review

Oxidative stress and chronic inflammation are the common pathological bases of chronic diseases such as atherosclerosis, cancer, and cardiovascular diseases, but most of the treatment drugs for chronic diseases have side effects. There is an increasing interest to identify food-derived bioactive compounds that can mitigate the pathological pathways associated with oxidative stress and chronic inflammation. Egg white contain a variety of biologically active proteins, many of which have antioxidant and anti-inflammatory activities and usually show better activity after enzymatic hydrolysis. This review covers the antioxidative stress and anti-inflammatory activities of egg white proteins and their derived peptides and clarifies their mechanism of action in vivo and in vitro. In addition, the link between oxidative stress and inflammation as well as their markers are reviewed. It suggests the potential application of egg white proteins and their derived peptides and puts forward further research prospects.

Bioactivity of Cooked Standard and Enriched Whole Eggs from White Leghorn and Rhode Island Red in Exhibiting In-Vitro Antioxidant and ACE-Inhibitory Effects

Hen breed, diet enrichment, cooking methods, and gastrointestinal (GI) digestion modulates the bioaccessibility of the bioactive compounds in eggs, but their synergistic role in modulating bioactivity is still unclear. The present study evaluates the effect of hen breed, diet enrichment, and GI digestion on the cooked whole egg-derived peptides in-vitro antioxidant and antihypertensive activities. Standard and enriched whole eggs from White Leghorn (WLH) and Rhode Island Red (RIR) hens were boiled or fried and subjected to GI digestion. Antioxidant activity was measured through oxygen radical absorbance capacity (ORAC) and gastrointestinal epithelial cell-based assays, and the antihypertensive capacity by in-vitro Angiotensin-I Converting Enzyme (ACE) inhibition assay. WLH fried standard egg hydrolysate showed a high ORAC antioxidant activity but failed to show any significant antioxidant effect in the cell-based assay. No significant differences were observed in the antihypertensive activity, although enriched samples tended to have a higher ACE-inhibitory capacity. The peptide profile explained the antioxidant capacities based on antioxidant structural requirements from different peptide fractions, while previously reported antihypertensive peptides were found in all samples. The study validates the importance of physiologically relevant models and requires future studies to confirm mechanisms that yield bioactive compounds in whole egg hydrolysates.

Comparison Study of Cytotoxicity of Bare and Functionalized Zinc Oxide Nanoparticles

In this paper, a study of the cytotoxicity of bare and functionalized zinc oxide nanoparticles (ZnO NPs) is presented. The functionalized ZnO NPs were obtained by various types of biological methods including microbiological (intra- and extracellular with Lactobacillus paracasei strain), phytochemical (Medicago sativa plant extract) and biochemical (ovalbumin from egg white protein) synthesis. As a control, the bare ZnO NPs gained by chemical synthesis (commercially available) were tested. The cytotoxicity was measured through the use of (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) dye as well as lactate dehydrogenase (LDH) assays against murine fibroblast L929 and Caco-2 cell lines. As a complementary method, scanning electron microscopy (SEM) was performed to assess the morphology of the tested cells after treatment with ZnO NPs. The microscopic data confirmed the occurrence of apoptotic blebbing and loss of membrane permeability after the administration of all ZnO NPs. The reactive oxygen species (ROS) concentration during the cell lines’ exposure to ZnO NPs was measured fluorometrically. Additionally, the photocatalytic degradation of methylene blue (MB) dye in the different light conditions, as well as the antioxidant activity of bare and functionalized ZnO NPs, is also reported. The addition of all types of tested ZnO NPs to methylene blue resulted in enhanced rates of photo-degradation in the presence of both types of irradiation, but the application of UV light resulted in higher photocatalytic activity of ZnO NPs. Furthermore, bare (chemically synthetized) NPs have been recognized as the strongest photocatalysts. In the context of the obtained results, a mechanism underlying the toxicity of bio-ZnO NPs, including (a) the generation of reactive oxygen species and (b) the induction of apoptosis, is proposed.

Tea polyphenols increase the antioxidant status of laying hens fed diets with different levels of ageing corn

This study was conducted to evaluate the effects of ageing corn levels (stored for 4 years) with or without the supplementation of tea polyphenols (TPP) on the performance, egg quality and antioxidant status of laying hens. A total of 288 Lohmann commercial laying hens (63-week-old) were used under a 2 × 4 factorial arrangement with 4 levels of dietary ageing corn (0%, 25%, 50%, or 100%) and 2 levels of TPP (0 and 600 mg/kg) for 8 wk. Dietary ageing corn linearly decreased (P < 0.05) the egg production, serum total antioxidant capacity (T-AOC), liver glutathione peroxidase (GSH-Px) of laying hens, yolk index, yolk colour, 1,1-diphenyl-2-picrylhydrazyl (DPPH) value and the reducing power value of egg yolk, but it linearly increased (P < 0.05) the feed conversion rate, ovary malondialdehyde (MDA) content of laying hens, and the protein carbonyl content of egg yolk. Tea polyphenol supplementation increased (P < 0.05) the serum T-AOC, serum superoxide dismutase (SOD), liver SOD, liver GSH-Px, ovary SOD, GSH-Px, the expression of antioxidant-related genes of laying hens, albumen height, Haugh unit, DPPH value and the majority free amino acids of egg yolk, but it decreased (P < 0.05) the serum MDA content of laying hens, MDA and protein carbonyl of egg yolk. In conclusion, the ageing corn significantly reduced the performance, egg quality, antioxidant status and egg antioxidant capacity of laying hens, while TPP supplementation partially counteracted the adverse effects, especially antioxidant status and egg antioxidant capacity of laying hens.

Heat-induced gel properties and gastrointestinal digestive properties of egg white produced by hens fed with selenium-enriched yeast

The aim of this study was to investigate the effect of selenium enrichment on the gel properties and gastrointestinal digestive properties of egg white. Results of texture profile analysis, scanning electron microscopy and differential scanning calorimetry showed that the heat-induced gel of selenium-enriched egg white (EW-2) exhibited higher gel strength, smoother microstructure, and higher thermal denaturation temperature than ordinary egg white (EW-1), which might be due to the change of ovomucin and ovotransferrin content. The gastrointestinal digestive products of the EW-2 protein contained a higher proportion of small peptides and more free amino acids than those of EW-1. Results of oxygen radical absorbance capacity and cellular antioxidant activity assays indicated that digestive products of the EW-2 protein exhibited stronger antioxidant activity than those of the EW-1 protein. In summary, Se enrichment improved heat-induced gel properties of egg white, and promoted the gastrointestinal digestion of egg white protein.

Chemical-free recovery of crude protein from livestock manure digestate solid by thermal hydrolysis

Protein is becoming an increasingly important resource for a variety of commercial applications. Yet, a large volume of protein is being wasted. Notably, livestock manure solids have a significant content of protein which is not only underutilized, but prone to runoff and eventual breakdown to reactive nitrogen compounds, contributing to eutrophication. It would be desirable to remove protein before it causes environmental hazards and then convert it to value-added commercial applications. We have developed a novel thermal hydrolysis process (THP) to extract crude protein from livestock manure solid, or manure digestate solid (MDS) in particular, without the use of any chemical. We demonstrate the versatility of our new process to control the molecular weight (MW) distribution of the extracted protein hydrolysate (PH). The antioxidant activity of the crude protein hydrolysate (CPH) has been examined through Oxygen Radical Absorbance Capacity Assay. The results have shown that our CPH had its antioxidant capacity against the peroxyl radical similar to that of vitamin E and exhibited almost 7 times as strong inhibition against the hydroxyl radical as vitamin E. We also evaluated the nutritional value of our PH by analyzing its amino acid composition and the MW distribution through amino acid analysis, SDS-PAGE, and MALDI-TOF mass spectroscopy. The characterizations have revealed that the PH recovered from MDS had 2.5 times as much essential amino acids as soybean meal on dry matter basis, with the MW distribution ranging from over a 100 Da to 100 KDa. Finally, the protein powder was prepared from the extracted CPH solution and its composition was analyzed.

Oral delivery of self-assembling bioactive peptides to target gastrointestinal tract disease

Peptides are known for their diverse bioactivities including antioxidant, antimicrobial, and anticancer activity, all three of which are potentially useful in treating colon-associated diseases. Beside their capability to stimulate positive health effects once released in the body, peptides are able to form useful nanostructures such as hydrogels. Combining peptide bioactivity and peptide gel-forming potentials can create interesting systems that can be used for oral delivery. This combination, acting as a two-in-one system, has the potential to avoid the need for delicate entrapment of a drug or natural bioactive compound. We here review the context and research progress, to date, in this area.

Physicochemical and Antioxidant Properties of Gelatin and Gelatin Hydrolysates Obtained from Extrusion-Pretreated Fish (Oreochromis sp.) Scales

Fish gelatin and its hydrolysates exhibit a variety of biological characteristics, which include antihypertensive and antioxidant properties. In this study, fish gelatins were extracted from extrusion-pretreated tilapia scales, and then subjected to analyses to determine the physicochemical properties and antioxidant activity of the extracted gelatins. Our findings indicate that TSG2 (preconditioned with 1.26% citric acid) possessed the greatest extraction yield, as well as higher antioxidant activities compared with the other extracted gelatins. Hence, TSG2 was subjected to further hydrolyzation using different proteases and ultrafiltration conditions, which yielded four gelatin hydrolysates: TSGH1, TSGH2, TSGH3, and TSGH4. The results showed that TSGH4 (Pepsin + Pancreatin and ultrafiltration < 3000 Da) had a higher yield and greater antioxidant activity in comparison with the other gelatin hydrolysates. As such, TSGH4 was subjected to further fractionation using a Superdex peptide column and two-stage reverse-phase column HPLC chromatography, yielding a subfraction TSGH4-6-2-b, which possessed the highest 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity compared with the other fractions. Further LC-ESI/MS/MS analysis of TSGH4-6-2-b suggested two novel peptides (GYDEY and EPGKSGEQGAPGEAGAP), which could have potential as naturally-occurring peptides with antioxidant properties. These promising results suggest that these antioxidant peptides could have applications in food products, nutraceuticals, and cosmetics.

Radioprotective effects of Cryptosporidium parvum lysates on normal cells

Two fractions, small and big (CpL-S, CpL-B), from Cryptosporidium parvum lysate (CpL) were prepared and its radioprotective activity was evaluated on normal cells. Both fractions improved cell viability of normal cells in a dose-dependent manner. 20 μg CpL-S and CpL-B improved cell viability of 10 Gy irradiated COS-7 cells by 38% and 34% respectively, while in HaCat cells 16% and 18% improved cell viability was observed, respectively. CpL-S scavenged IR-induced ROS more effectively compared to the CpL-B, 50% more in COS-7 cells and 15% more in HaCat cells. There was a significant reduction of γH2AX, Rad51, and pDNA-PKcs foci in CpL-S treated cells compared to control or CpL-B group at an early time point as well as late time point. In 3D skin tissue, CpL-S reduced the number of γH2AX positive cells by 31%, compared to control, while CpL-B reduced by 9% (p < 0.005) at 1 h post 10 Gy irradiation and 22% vs 6% at 24 h post-IR (p < 0.005). Taken together, CpL-S significantly improved cell viability and prevented radiation-induced DNA damage in normal cells as well as 3D skin tissues by effectively scavenging ROS generated by ionizing radiation. CpL-S can be a candidate for radioprotector development.

Bioactive Peptides and Hydrolysates from Egg Proteins as a New Tool for Protection Against Cardiovascular Problems

The aim of the present work is to review the potential beneficial effects of dietary supplementation with bioactive egg protein hydrolysates or peptides on cardiometabolic changes associated with oxidative stress. The development of nutritionally improved food products designed to address specific health concerns is of particular interest because many bioactive food compounds can be potentially useful in various physiological functions such as for reducing oxidative stress. The results presented suggest that egg hydrolysates or derived peptides could be included in the diet to prevent and/or reduce some cardiometabolic complications associated with oxidative stress-related diseases.

Effects of periodical application of bioactive peptides derived from cottonseed on performance, immunity, total antioxidant activity of serum and intestinal development of broilers

This experiment aimed to examine the effect of periodical application of bioactive peptides derived from cottonseed (BPC) in comparison with using sub-therapeutic doses of lincomycin and the excessive inclusion of vitamin E on performance, immunity, total antioxidant capacity of serum and intestinal morphology of broiler chickens. A total of 240 one-d-old male broiler chicks with similar initial weight (Ross strain) were randomly assigned to 6 groups (8 chicks/pen): non-treated group (basal diet), basal diet supplemented with 2 mg/kg lincomycin, basal diet supplemented with 50 IU vitamin E, basal diet supplemented with 6 g BPC/kg in starter period, basal diet supplemented with 6 g BPC/kg in starter and grower periods and basal diet supplemented with 6 g BPC/kg throughout the whole experiment. The highest final body weight was obtained in the group supplemented with BPC in starter and grower periods. In the finisher phase, broilers fed the diet containing BPC in the starter period and in the whole trial had significantly (P < 0.05) better feed conversion ratios (FCR). Jejunal villus height was significantly elevated in broilers supplemented with antibiotic (P < 0.001), furthermore it tended to be greater in broilers fed BPC in the starter period. The jejunal villus height-to-crypt depth ratio was significantly (P < 0.01) higher in broilers fed the diet containing antibiotic in comparison to other groups. Humoral immune response against Newcastle disease vaccine tended to be elevated in broilers fed the diet containing BPC in the whole trial (P > 0.05). Broilers supplemented with BPC in starter and grower, and in the whole trial had significantly (P < 0.05) higher antibody titers against sheep red blood cells (SRBC). The highest total antioxidant capacity was obtained in broilers supplemented with the excessive level of vitamin E, furthermore it tended to improve in broilers fed the diet containing BPC in the whole trial. In summary, the results of the study indicated that addition of BPC in broiler diets in the whole trial could improve FCR, immune responses and total antioxidant activity of serum, and BPC could be used in broiler diets as an alternative to in-feed antibiotics.

Physical, structural and antioxidant properties of brewer's spent grain protein films

BACKGROUND

The development of brewer's spent grain protein (BSG-PC) films with potential active packaging properties was investigated. Films were prepared by casting protein dispersions at different pH values (2, 8, 11), plasticizers [polyethylene glycol (PEG) or glycerol] and levels (0-0.25 g g^-1 ) of PEG. Mechanical, water-barrier and solubility, optical, antioxidant (reducing power, ABTS^•+ and lipidic radical scavenging), and antimicrobial properties of films were determined. Also, the structural characteristics of films were evaluated by attenuated total reflectance-Fourier transform infrared spectroscopy.

RESULTS

Only films prepared at pH 2 and plasticized by PEG were homogeneous in appearance and could be manipulated; thus, different levels of PEG were studied at this pH. Higher PEG concentrations increased water solubility, water vapor permeability and elongation at break, and decreased tensile strength and elastic modulus. PEG increased α-helix structure only when 0.10 g PEG g-1 BSG-PC was used. This could be related to the better mechanical properties of F_0.10 films (higher tensile strength, and elastic modulus) with respect to the other films. Antioxidant activity depended on PEG concentration, whereas no antimicrobial properties against Bacillus cereus, Salmonella newport and Penicillium corylophylum were detected.

CONCLUSION

The formulations with 0.10 and 0.15 g PEG g^-1 BSG-PC appear to be the most promising, balancing mechanical, water-barrier properties and the antioxidant capacity of these films. Moreover, BSG proteins could be a cheap alternative for the preparation of biodegradable films, which are capable of being used as active food packaging. © 2020 Society of Chemical Industry.

An insight on egg white: From most common functional food to biomaterial application

Natural egg white tis widely used as an ingredient in nutritional foods and for food processing. Due to its characteristic foaming, emulsification, adhesion, and gelation, and its heat setting, biocompatibility, and low cost, research into the application and development of egg white in biomaterials, especially medical biomaterials, have been receiving attention. The composition and characteristics of egg white protein, and the physical mixing and chemically cross-linking of egg white with other materials used to make degradable packaging films, bioceramics, bioplastics, biomimetic films, hydrogels, 3D scaffolds, bone regeneration, biopatterning, biosensors, and so forth, are reviewed in detail in this report. The novel egg white-based biomaterials in various forms and applications could be constructed mostly through physical treatments such as ultrasonic wave, ultraviolet, laser and other radiation or high-temperature calcination. Furthermore, the application and prospects for the use of egg white in biomaterials is also discussed.

Antioxidant Properties of Egg White Hydrolysate Prevent Mercury-Induced Vascular Damage in Resistance Arteries

Aim: We investigated the antioxidant protective power of egg white hydrolysate (EWH) against the vascular damage induced by mercury chloride (HgCl2) exposure in resistance arteries. Methods: Male Wistar rats received for 60 days: (I) intramuscular injections (i.m.) of saline and tap water by gavage - Untreated group; (II) 4.6 μg/kg of HgCl2 i.m. for the first dose and subsequent doses of 0.07 μg/kg/day and tap water by gavage - HgCl2 group; (III) saline i.m. and 1 g/kg/day of EWH by gavage - EWH group, or (IV) the combination of the HgCl2 i.m. and EWH by gavage - EWH + HgCl2 group. Blood pressure (BP) was indirectly measured and dose-response curves to acetylcholine (ACh), sodium nitroprusside (SNP), and noradrenaline (NE) were assessed in mesenteric resistance arteries (MRA), as in situ production of superoxide anion, nitric oxide (NO) release, vascular reactive oxygen species (ROS), lipid peroxidation, and antioxidant status. Results: Egg white hydrolysate prevented the elevation in BP and the vascular dysfunction after HgCl2 exposure; restored the NO-mediated endothelial modulation and inhibited the oxidative stress and inflammatory pathways induced by HgCl2. Conclusion: Egg white hydrolysate seems to be a useful functional food to prevent HgCl2-induced vascular toxic effects in MRA.