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BACKGROUND Hydrogen sulfide (H2 S) is a known signaling molecule in plants, which has the ability to delay fruit ripening. Our previous studies have shown that H2 S treatment could delay the maturation of kiwifruits by inhibiting ethylene production, improving protective enzyme activities, and decreasing the accumulation of reactive oxygen species to protect the cell membrane during storage. The mechanism related to the way in which H2 S affected kiwifruit maturation was still unclear. We performed transcriptome sequencing to explore the influences of H2 S on the softening of kiwifruit. RESULTS The firmness and the soluble solids content (SSC) of the kiwifruit were significantly better maintained with H2 S treatment compared to the control during the storage period (P

BACKGROUND The texture and structure of the duck egg white (DEW) gel under salt and heat treatment are crucial to its digestibility. Specifically, the structural changes of food protein gels have been recognized for their potential to regulate in vitro digestion. In this study, the effects of gel characteristics and simulated in vitro gastrointestinal digestion of DEW under combined salt and heat treatment were investigated. RESULTS With the increase in salting time and temperature, a porous opaque gel with large particles was formed, the moisture content of DEW showed a downward trend, and the same was true for hardness changes. The microstructure suggested that, with the penetration of NaCl, DEW proteins were denatured, and the protein molecules gradually unfolded and then aggregated after 7 days. The secondary structure revealed that, as the salting time and temperature increased, the proportion of intermolecular β-sheets and α-helices decreased. In terms of in vitro digestion, the highest digestibility was obtained at 14 days of salting combined with 100 °C heat treatment, and the digestibility was the lowest when marinated for 7 days at 121 °C. Liquid chromatography and tandem mass spectrometry (LC-MS/MS) indicated that the number of different types of peptides and specific peptides was positively correlated with the salting time and temperature of the DEW at the end of gastric digestion. CONCLUSIONS Heat treatment at 100 °C has a higher in vitro digestibility than at 121 °C. Gels with low hardness, large pores, and rough textures are easier to digest by pepsin and release more peptides. © 2021 Society of Chemical Industry.

Peptides DEDTQAMPFR (DR-10), MLGATSL (ML-7), SLSFASR (SR-7), and MSYSAGF (MF-7) derived from simulated gastrointestinal digestion of preserved egg white (SGD-PEW) exerted anti-inflammatory effects on Caco-2 cells. Here, we aimed to evaluate the anti-inflammatory effects of these peptides derived from SGD-PEW in a mouse model of dextran sodium sulfate (DSS)-induced colitis. The results showed that DR-10, ML-7, SR-7 and MF-7 significantly ameliorated the clinical symptoms of DSS-induced mice colitis, such as weight loss, disease activity index (DAI), colon shortening, spleen hypertrophy and histological scores. Treatment with DR-10, ML-7, SR-7 and MF-7 also significantly inhibited the local secretion of pro-inflammatory cytokines TNF-α and IL-6 and markedly decreased the gene expression of pro-inflammatory cytokines, including TNF-α, IL-6, IL-17, IL-1β, IFN-γ and MCP-1, in DSS-induced mice colitis. Overall, MF-7 showed the best effect of alleviating DSS-induced colitis among the four peptides. These results suggested that MF-7, DR-10, ML-7 and SR-7 may be a potential promising candidate for the treatment of inflammatory bowel disease (IBD).

Ovotransferrin (OVT) is one of the major proteins in avian albumen that exerts diverse biological activities. This study is aimed to investigate the antiviral effect and mechanism of OVT from the avian egg. Effects of OVT on vesicular stomatitis virus (VSV)-infected mouse peritoneal macrophage were detected by real-time quantitative polymerase chain reaction, enzyme-linked immunosorbent assay, and western blot. In OVT-pretreated mouse peritoneal macrophages, results showed that replication of VSV was significantly suppressed and production of type I interferon (IFN) was increased. OVT down-regulated ring finger protein 125 (RNF125) production and up-regulated retinoic-acid-inducible gene I (RIG-I) expression by the nuclear factor-κB signalling pathway, resulting in the enhancement of the production of type I IFN. It demonstrated that the antiviral effect of OVT on innate immunity is enhanced by promoting type I IFN expression, indicating its potential as a functional food ingredient.

Proteins and bioactive peptides in avian egg whites exert anti-inflammatory activity. Here, we aimed to evaluate the anti-inflammatory effect of ovotransferrin (OVT) and its di-peptides by simulated peptide-cut using an in vitro model of TNF-α-induced inflammation in Caco-2 cells. Results showed that co-treatment with OVT can’t inhibit the IL-8 secretion in TNF-α-induced Caco-2 cells. Among 18 di-peptides derived from OVT based on simulated peptide-cut, CR, FL, HC, LL and MK markedly decreased IL-8 secretion. Furthermore, these five di-peptides were able to significantly inhibited gene expression of pro-inflammatory cytokines, including TNF-α, IL-8, IL-6, IL-1β, and IL-12, and promoted gene expression of anti-inflammatory cytokines, such as IL-10, in Caco-2 cells. CR, FL, HC, LL and MK inhibited the phosphorylation of inhibitor of κB (IκB). Meanwhile, CR and HC decreased the phosphorylation of p-JNK and p-p-38. These results indicated that CR and HC inhibited the NF-κB and MAPK signaling pathway in TNF-α-induced Caco-2 cells. Nevertheless, LL, FL and MK exerted their anti-inflammatory activity via MAPK signaling pathway. The study suggested that CR, FL, HC, LL and MK have the potential to attenuate intestinal inflammation.

Ethnopharmacological relevance Egg yolk oils (EYO) is a traditional Chinese medicine obtained from Gallus gallus domesticus Brisson, which has been used to treat inflammatory related diseases such as cheilitis, ulceration and acute anal fissure. However, the detailed anti-inflammatory mechanism of EYO is still unknown. Aim of the study The anti-inflammatory activity and mechanism of EYO were investigated in tumor necrosis factor (TNF)-α induced Caco-2 cells. Materials and methods EYO was obtained by direct-heat extraction (HE), ethanol extraction (EE) and petroleum ether extraction (PE), respectively. Fatty acid compositions of three EYO were measured by gas chromatography (GC). Cell viability, enzyme-linked immunosorbent assay (ELISA), transcriptome, RT-PCR and Western blotting were also performed. Results Fatty acid compositions of three EYO were different with varied extraction methods. EYO significantly reduced interleukin (IL)-8 secretion. EYO exerted anti-inflammatory effect via coordinating regulation of Nrf2/NF-κB pathways based on the results of transcriptome, Q-PCR and Western blotting. In detail, PE and HE inhibited the NF-κB pathway, whereas EE exerted anti-inflammatory activity via the Nrf2/NF-κB pathways. Conclusions The aforementioned results showed the anti-inflammatory mechanism of EYO. These findings might be beneficial to clinical applications of EYO.

Proteins and bioactive peptides in avian egg white exert diverse biological activities. This study is designed to investigate the effect of protease hydrolysates from ovotransferrin (OVT) on bone marrow-derived dendritic cells (BMDCs) maturation. The results show that OVT-derived pepsin hydrolysate effectively inhibits lipopolysaccharide (LPS)-induced BMDCs maturation by reducing the expression levels of MHC-II, CD83, CD86 and the production of TNF-α, IL-12p70, and RANTES, but increases the production of IL-10. In addition, OVT-derived pepsin hydrolysate impairs the ability of LPS-stimulated BMDCs to induce allogeneic T lymphocyte proliferation and decreases the production of IFN-γ by activated T cells. In contrast, OVT-derived trypsin hydrolysate induces DCs maturation in terms of increasing the expression levels of MHC-II and the costimulatory molecules CD83 and CD86 and the production of TNF-α, IL-12p70 and RANTES. Furthermore, OVT-derived trypsin hydrolysate improves the ability of LPS-stimulated DCs to induce allogeneic T lymphocyte activation. Blockage of LPS-induced p38 MAPK and JNK activation and inducing ERK activation contribute to the inhibitory effect of OVT-derived pepsin hydrolysate on DCs, whereas OVT-derived trypsin hydrolysate induces DCs maturation through JNK and ERK activation. These results indicate that OVT-derived protease hydrolysate have an immunomodulatory function and could be applied as a potential functional food ingredient to regulate body immunity by modulating DC maturation.

In this paper, the relationship between protein structure changes and in vitro digestion of preserved egg white (PEW) during pickling was studied. Results showed that as the pickling time increased, moisture content of PEW exhibited a decreasing trend, pH value and hardness of PEW exhibited an increasing trend. Environmental Scanning Electron Microscopy (ESEM) revealed that alkali-treated duck egg white could form a more compact gel network structure during pickling. Transmission Electron Microscopy (TEM) showed that PEW consisted of two sorts of structures, namely fibrillar (from 7th to 21st day) and particulate (from 28th to 42nd day). Fourier Transform Infrared (FTIR) spectroscopy showed that there was an increase in the content of β-sheets and a decrease in the content of α-helices during pickling. Protein digestibility of PEW was highest at day 14 and the lowest at day 42. Moreover, the content of β-sheets was negatively correlated with protein digestibility. Peptides identification using LC-MS/MS highlighted that the number of different peptides were positively correlated with the pickling. The number of unique peptides was negatively correlated with protein digestibility at the end of gastric and intestinal digestion. This study would provide guidance for studying nutritional value and controlling quality of preserved eggs.

Nitric oxide (NO) is a signal molecule that can regulate fruit physiology. Several studies have indicated that NO can inhibit the ripening of kiwifruit, but the mechanism underlying this process is unresolved. This study used transcriptome analysis to identify the essential genes related to NO regulation during kiwifruit softening. NO gas fumigation (15 μl L-1) significantly delayed kiwifruit softening. There were 736 differentially expressed genes (DEGs) between the NO treatment and the control. The expression levels of polygalacturonase (PG), pectate lyase (PL), β-galactosidase (β-GAL), pectinesterase (PE), and the beta-amylases-related genes decreased in response to the NO treatment, while those of four genes encoding cellulose synthase increased. The expression of genes related to ethylene biosynthesis and signal transduction also differed; the expression levels of 1-aminocyclopropane carboxylic acid oxidase (ACO), the ethylene receptors (ERS1, ETR2), and the ethylene-responsive transcription factors (ERF016, ERF7, ERF010, ERF062, ERF110, ERF037, ERF008, ERF113, ERF12, ERF095) were lower in the NO-treated kiwifruit. Expression of the calcium ion (Ca2+) signal-related genes (CNGC1, CPK1, CIPK2, CML31, CML48, ZIFL1) significantly differed and may be involved in the regulation of the NO softening response. These findings add to our understanding of the molecular mechanisms of the NO-delayed softening response in kiwifruit.

Current study aimed to evaluate the effects of fumigation with 15 μl L−1 nitric oxide (NO) on the quality of ‘Newhall’ navel orange fruit during storage at 5 °C. Fruits quality parameters, decay rate, antioxidant capacity, antioxidant enzymes activities and disease resistance related enzymes activities were evaluated. NO treatment significantly inhibited the increasing weight loss, maintained soluble solid content (SSC), titratable acid (TA) and vitamin C (VC) contents (P

The effects of fumigation with NO, H2S and combination of both on the quality, ethylene biosynthesis and softening of postharvest ‘Dahong’ peach fruit were investigated in current study. Results showed that NO or H2S significantly inhibited the increase of rot index, soluble solid contents, decrease of firmness along with titratable acid contents (P

In order to illuminate the forming process of salted egg, the effects of the brine solution with different salt concentrations on the physicochemical properties, textural properties, and microstructures of duck eggs were evaluated using conventional physicochemical property determination methods. The results showed that the moisture contents of both the raw and cooked egg whites and egg yolks, the springiness of the raw egg yolks and cooked egg whites exhibited a decreasing trend with the increase in the salting time and salt concentration. The salt content, oil exudation and the hardness of the raw egg yolks showed a constantly increasing trend. Viscosity of the raw egg whites showed an overall trend in which it first deceased and then increased and decreased again, which was similar to the trend of the hardness of the cooked egg whites and egg yolks. As the salting proceeded, the pH value of the raw and cooked egg whites declined remarkably and then declined slowly, whereas the pH of the raw and cooked egg yolks did not show any noticeable changes. The effect of salting on the pH value varied significantly with the salt concentration in the brine solution. Scanning electron microscopy (SEM) revealed that salted yolks consist of spherical granules and embedded flattened porosities. It was concluded that the treatment of salt induces solidification of yolk, accompanied with higher oil exudation and the development of a gritty texture. Different salt concentrations show certain differences.