This study prepared and structurally characterized peptides with different molecular masses from walnut meal protein by enzymatic hydrolysis with a mixture of two proteases followed by ultrafiltration, and it also explored the antioxidant activities of walnut peptides and their protective effects on oxidative damage in HepG2 cells. The results showed that the antioxidant activity of walnut protein hydrolysate (WPH) with molecular mass < 1 kDa was the strongest, with half-maximal inhibitory concentration (IC50) of 11.47, 35.67 and 49.72 mg/mL for hydroxyl radical, 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation scavenging capacity, respectively. Moreover, the < 1 kDa walnut peptide fraction could reduce the reactive oxygen species (ROS) content and increase the superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GSH-Rx) and glutathione peroxidase (GSH-Px) activity in HepG2 cells. The walnut peptide was irregular in shape and had a smooth surface and dense structure with numerous rough patterns and pores. The walnut peptide had a maximum absorption peak at 225 nm wavelength. The most abundant secondary structures of the walnut peptide were random coil (36.5%) and β-sheet (36.6%). These results indicate that the < 1 kDa walnut peptide has a protective effect against oxidative damage in HepG2 cells.

In order to optimize the calibration set for near-infrared modeling of the protein content in wheat flour, the binary dragonfly algorithm (BDA) was used to select representative samples from the primary calibration set divided by the traditional Kennard/Stone (K/S) method. Based on the representative samples, a partial least square regression (PLSR) model for estimating the protein content in wheat flour was established, and the prediction set was employed to evaluate the stability and prediction performance of the model. The results indicated that an optimal calibration set with 30 samples was selected finally by BDA, and the proposed model exhibited a coefficient of determination of prediction (Rp2) of 0.956 4 and a root mean square errors of prediction (RMSEP) of 0.278 1, which increased by 1.87% and decreased by 15.57% compared with those (0.938 8 and 0.329 4) from K/S partition of 100 primary calibration sets, respectively. The average number of calibration sets selected from 10 BDA experiments was 30.2, and the protein content of wheat flour was predicted better by the 10 models developed than that obtained based on the primary calibration set. Therefore, BDA can select a small number of representative calibration set samples based on which a PLSR model with good robustness and high prediction accuracy for the protein content of wheat flour can be established. The proposed method can provide an efficient tool for calibration set selection in near-infrared spectroscopic analysis of the quality of wheat flour.

In this study, the wild type 6421 and the fruit color mutant E55 of pepper were evaluated for fruit color, pigment contents and quality components at different developmental stages. The results demonstrated that the fruit color of 6421 and E55 changed from green to yellow and then to red, and from green to brown and then to orange, respectively, as the fruit developed from mature green to ripe. For both 6421 and E55, the color parameters a* and C* increased, while hue angle (h) value decreased. Furthermore, chlorophyll (Chl) content declined, whereas carotenoid (Car) content increased. Additionally, the contents of VC, soluble sugar, soluble protein and capsaicin increased, while cellulose content decreased. At the mature green stage, there was no significant difference between 6421 and E55 in five color parameters (L*, a*, b*, C*, and h values), Chl and Car contents or six quality indicators (cellulose, VC, soluble sugar, soluble protein, and capsaicin contents) (P > 0.05). During the color-turning to ripening stages, L*, b* and C* values and VC and soluble sugar contents were significantly higher and soluble protein and cellulose contents were significantly lower in E55 than in 6421 (p < 0.05), whereas capsaicin contents were not significantly different between E55 and 6421 (p > 0.05). Correlation analysis showed that for both 6421 and E55, Chl and Car contents were significantly or extremely significantly correlated with each quality parameter except for cellulose content. Among the tested quality indicators, soluble sugar, soluble protein, and capsaicin contents were significantly or extremely significantly positively correlated with each other, while cellulose content was significantly or highly significantly negatively correlated with the other indicators. This study can serve as a theoretical basis for research on the coloration mechanism of peppers as well as for the screening and breeding of high-quality pepper cultivars.

In this study, the synergistic effect of Quillaja saponin (QS) and soybean protein isolate (SPI) on stabilizing emulsion gels was used to prepare plant-based mayonnaise (PM) with high protein content and reduced fat content. Comparative characterization of PM and two commercially mayonnaises in terms of appearance, droplet size, texture, rheological properties, thermal and freeze-thaw stability was conducted by static light scattering, laser confocal scanning microscopy (LCSM), small deformation rheology and texture profile analysis (TPA). It was found that high-protein and fat-reduced MP (10% SPI and 50% fat or 11% SPI and 40% fat, m/m) which was compared to commercial mayonnaises in terms of appearance, spreadability, texture and rheological properties was made using 10% SPI and 0.18% QS or 10% SPI, 0.18% QS and 1% SPI gel particles (SGPs) as protein ingredients. In the systems, QS not only endowed a viscosity-thinning texture modifier to protein-rich emulsion products, but also imparted superior thermal stability and freeze-thaw stability to SPI-based emulsion gels. These findings will provide theoretical and technical guidance for the development and application of high-protein and fat-reduced plant-based mayonnaise.

This study investigated the effect of foliar versus soil application of selenium on the selenium content of sweet potato leaves and the antioxidant activity of sweet potato leaf proteins. The results showed that both foliar and soil applications of selenium could increase the protein-bound selenium content of sweet potato leaves. The protein-bound selenium contents of the foliar and soil selenium treatment groups at 1.6 mg/mL concentration were 20.10 and 1.68 mg/g, respectively. Selenium enrichment could improve the antioxidant activity of sweet potato leaf proteins. The superoxide anion free radical scavenging capacity of sweet potato leaf proteins was increased by 19.17% with foliar selenium enrichment. According to correlation analysis, the total selenium content and protein-bound selenium content of sweet potato leaves significantly affected the antioxidant activity, and the total phenolic and total flavonoid contents also affected the antioxidant activity. In conclusion, compared with soil selenium application, foliar selenium application was better in increasing the protein-bound selenium content of sweet potato leaves.

A physically cross-linked hydrogel was constructed by electrostatic interaction between chitosan (CS) and sodium hyaluronate (SH), and its texture properties, microstructure and functional properties were characterized. Meanwhile, the influence of loading with one of the probiotics Lactobacillus rhamnosus and Pediococcus acidilactici on texture characteristics and microstructure of the hydrogel was evaluated, the loading performance was analyzed, and the release mechanism of probiotic-loaded hydrogels in simulated gastroenteric fluid was explored. The results showed that CS-SH hydrogel, which was formed through electrostatic crosslinking, had good texture properties and bacteria-loading properties, and the loading capacity of 0.2 g (dry mass) of hydrogels for L. rhamnosus and P. acidilactici was 1.15 × 109 and 1.25 × 109 CFU, respectively. The probiotic-loaded hydrogel was continuously released in simulated intestinal fluid, and its release mechanism was through surface erosion. The maximum viable counts of L. rhamnosus and P. acidilactici in simulated intestinal fluid were 6.30 and 6.12 (lg(CFU/mL)), respectively. To sum up, CS-SH hydrogel is a potential probiotic delivery carrier that can be continuously released in simulated intestinal fluid. This study provides theoretical guidance and a research basis for the application and mechanism of action of physically crosslinked hydrogels in the field of probiotic loading.

In order to solve the problem of the low bioavailability of 6-shogaol (6S), in this study, zein-sodium caseinate nanoparticles (ZCP) were constructed by the anti-solvent precipitation method as a nano-delivery carrier for 6S. The physicochemical properties of 6S-loaded zein nanoparticles (ZCP-6S) were characterized and the bioavailability was investigated by in vitro simulated digestion, Caco-2 cell model and pharmacokinetic studies in rats. The particle size distribution, microstructure and chemical structure of ZCP-6S were characterized by laser particle size analyzer, transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy. The results indicated that the nanoparticles were spherical in shape, with small particle size and uniform distribution. 6S might interact with zein through non-covalent bonds. The in vitro simulated digestion results showed that ZCP-6S increased the bioaccessibility of 6S to (75.34 ± 9.82)%. Moreover, ZCP-6S significantly enhanced the uptake and transport of 6S by Caco-2 cells. After 4 h treatment, the cell uptake increased by (0.36 ± 0.06) μg/mg. The concentration of 6S in the basolateral side of the Caco-2 cell model increased by (1.06 ± 0.06) μg/mL. In addition, pharmacokinetic studies showed that the relative oral bioavailability of 6S increased by 3.28 times after nanoparticle encapsulation. In summary, the bioaccessibility, cellular absorption and oral bioavailability of 6S were effectively improved by its encapsulation into zein nanoparticles.

In order to understand the formation process and interaction mechanism of complexes between ovalbumin (OVA) and fucoidan (FUC), turbidity titration, zeta potential measurement, circular dichroism (CD) spectroscopy, fluorescence spectroscopy and dynamic rheometer analysis were used to analyze the phase behavior and critical pH values (pHc, pHφ1 and pHmax) of OVA-FUC complexes. The zeta potential results showed that the that the critical pH for the formation of composite aggregates was closely related to the ratio of OVA to FUC and salt concentration. The zeta potential analysis indicated that the formation of composite aggregates was mainly driven by electrostatic interaction. As the OVA/FUC ratio increased, the critical pH shifted to a higher value. Low salt concentrations (c(NaCl) < 100 mmol/L) promoted the formation of aggregates, while high salt concentrations (c(NaCl) ≥ 100 mmol/L) significantly decreased the critical pH due to electrostatic shielding. Under acidic conditions (pH 4.5), maximum viscoelasticity was observedat an OVA/FUC ratio of 20:1 (m/m) and NaCl concentration of 400 mmol/L. Our study provides a theoretical basis for the development of functional products based on sulfated polysaccharide and egg white protein.

This work aims to study the in vitro antioxidant activity of selenium-enriched rape powder extract and its correlation with basic chemical components. The results showed that compared with regular rape powder extract, selenium-enriched rape powder extract contained more nitrogen compounds, polyphenols, flavonoids, total selenium and polysaccharide-bound selenium, and had higher Fe3+ reducing power, 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation, and hydroxyl free radical scavenging activity. Correlation analysis showed that the antioxidant activity was positively correlated with nitrogen compounds, total sugar, polyphenols, flavonoids, saponins, polysaccharides, total selenium, and polysaccharide-bound selenium. Partial correlation analysis showed that the antioxidant activity was only significantly or highly significantly positively correlated with polysaccharides and polysaccharide-bound selenium, which indicated that the difference in antioxidant activity between the two rape powder extracts may be mainly caused by the differences in polysaccharides and polysaccharide-bound selenium contents. In conclusion, there are differences in the basic chemical compositions of selenium-enriched and regular rape powder extracts, and selenium-enriched rape powder extract has a higher in vitro antioxidant activity. Polysaccharide-bound selenium was the major antioxidant component.

In order to investigate the application potential of prolyl endopeptidase (PEP) in the enzymatic preparation of bone collagen peptides, the amino acid sequence characteristics of bovine bone collagen (BBC), porcine bone collagen (PBC) and chicken bone collagen (CBC) were comparatively analyzed, and their potential enzymatic cleavage sites and theoretical hydrolysis degrees were predicted. Collagen hydrolyzed by PEP at 55 ℃ and pH 8.0 was characterized by hydrolysis degree, molecular mass distributionand scanning electron microscopy (SEM). Infrared spectroscopy, X-ray diffraction (XRD) and circular dichroism (CD) spectroscopy were used to explore the structural changes of collagen during enzymatic digestion. The results showed that PEP could hydrolyze the three collagens. The hydrolysis degree of PBC was the highest (51.35%), followed by those of BBC (22.81%) and CBC (29.81%). The molecular masses of the three collagen hydrolysates were mostly distributed below 500 Da. Spectroscopic analysis showed that PEP destroyed the triple helix structure of collagen, and then degraded it. Therefore, PEP can efficiently enzymatically hydrolyze collagen into small molecule peptides, which provides a basis for the enzymatic preparation of functional collagen-derived peptides.

This study investigated the effect of carvacrol stress on the physiological characteristics and transcriptome of Saccharomyces cerevisiae, a common spoilage yeast in fruit and vegetable products. The results showed that the minimum inhibitory concentration (MIC) of carvacrol on S. cerevisiae was 160 mg/mL. With the increase in temperature (20–40 ℃), the inhibitory effect of carvacrol (160 mg/mL) on yeast growth gradually increased. Environmental pH (3–4.5) had no significant impact on the inhibitory effect of carvacrol. However, the addition of fructose (20–80 g/L) significantly reduced the antifungal activity. Carvacrol treatment damaged the structure of the cell envelope of S. cerevisiae, increased the plasma membrane permeability and caused plasma membrane depolarization, resulting in leakage of intracellular substances, a decrease in mitochondrial membrane potential, an imbalance in intracellular Ca2＋ homeostasis, and a decrease in intracellular ATP content. The transcriptomic analysis revealed that carvacrol stress inhibited the biosynthesis of mitochondrial respiratory chain complexes, ATP synthase and mitochondrial ribosome (MR) proteins, which could block electron transport along the respiratory chain and interfere with life activities related to MR.

To investigate the microbial diversity and the correlation with metabolites in traditional fermented yak milk products, the study used high-throughput sequencing and gas chromatography-time-of-flight mass spectrometry (GC-TOF-MS) to analyze the microbial diversity and metabolite profiles of yak ghee, Qula, and yogurt. Results showed that the microbial communities of the three dairy products differed significantly at the genus level. The dominant bacterial genus in yak yogurt and Qula was Lactobacillus, while Lactococcus was dominant in ghee. The fungi Geotrichum and yeast were found in all samples. In particular, a high abundance of Pichi was detected in yak yogurt and Qula, and Kluyveromyce was exclusively present in yogurt, whereas the fungal genus composition varied considerably among ghee samples. Using metabolomics combined with multivariate statistical analysis, a total of 51 differential metabolites were identified. The characteristic metabolites of ghee were lipids and lipid-like molecules, and the characteristic metabolites of Qula and yogurt were similar, including organic acids and their derivatives as well as lipid and lipid-like molecules. A total of 12 metabolic pathways were found to be involved in the regulation of the flavor and quality of fermented yak milk products. Correlation analysis showed that Lactococcus and Geotrichum were negatively correlated with selected metabolites, while Lactobacillus and Kluyveromyce were positively correlated with most of the metabolites. Differences in the microbial community structure could lead to differences in the metabolite profile of fermented yak milk products. The results from this study provide a theoretical basis for better regulating the quality of fermented yak milk products.

In order to explore the effect of co-fermentation with Monascus and Aspergillus oryzae on the quality of soybean paste, the volatile flavor components in soybean pastes produced using pure and mixed cultures of A. oryzae (Piniang M003) and Monascus (PM001) were determined by headspace solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and comparatively analyzed by principal component analysis (PCA), and Illumina MiSeq sequencing technology was used to analyze the changes in the microbial community structure during the mixed culture fermentation process. Meanwhile, the correlation between the major microorganisms and the major flavor substances was analyzed. The results showed that the composition and content of flavor substances and the composition and relative abundance of microbial communities in the soybean paste produced by co-fermentation were significantly better than those in the soybean paste fermented with A. oryzae monoculture. The major flavor substances in soybean paste were significantly positively correlated with dominant genera such as Aspergillus, Bacillus, Monascus and Leuconostoc. The flavor quality of the soybean paste produced with a mixed culture of A. oryzae and Monascus in a ratio of 3:1 (m/m) was best. The results of the study showed that the mixed culture fermentation with Monascus and A. oryzae could significantly improve the flavor quality of soybean paste, which will be informative for the improvement of the flavor quality of soybean paste.

This study developed a real-time polymerase chain reaction (real-time PCR) method for the detection of Lactobacillus kefiranofaciens subsp. kefiranofaciens. Based on the 16S rDNA gene sequence and whole genome sequence of the type strain of L. kefiranofaciens subsp. kefiranofaciens ZW3, specific primers were designed and screened. The fluorescent dye SYBR Green I was used in the real-time PCR method. Its specificity, sensitivity and repeatability were evaluated, and this method was applied to detect several strains of this species and its mixtures with other lactic acid bacteria. The results showed that the proposed method was highly specific, sensitive and repeatable. The standard curve was linear with a determination coefficient (R2) of 0.965. Moreover, this method could specifically detect L. kefiranofaciens subsp. kefiranofaciens from its mixture with other lactic acid bacteria. In summary, the real-time PCR method could quickly and accurately detect L. kefiranofaciens subsp. kefiranofaciens, providing a new method for the specific qualitative and quantitative detection of L. kefiranofaciens subsp. kefiranofaciens.

Lycium ruthenicum Murr. polysaccharide (LRMP) was obtained by hot water extraction, its structural parameters such as monosaccharide composition, glycosidic linkages and chain conformation were analyzed, and its protective effect on ethanol-inducedinjuryin gastric mucosal epithelial cells (GES-1) was evaluated. The results showed that LRMP was composed of arabinose, xylose, galactose, glucose, fucose and galacturonic acid, and its terminus mainly consisted of arabinose, xylose, glucose and galactose residues. In aqueous solution, LRMP presented a typical random coil conformation with a mean square radius of (80.4 ± 1.0) nm. LRMP had no toxic effect on GES-1 cells, and 600 μg/mL LRMP could significantly ameliorate ethanol-induced damage, restore intracellular superoxide dismutase (SOD) activity, and reduce apoptosis rate in GES-1 cells. In conclusion, LRMP has potential application as a functional polysaccharide in the development of health foods.

This study developed a cell model of oxidative damage by treating PC12 cells for 24 h with 200 µmol/L H2O2 and determined the degree of oxidative stress by assaying the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and lactate dehydrogenase (LDH) and the level of malondialdehyde (MDA). Moreover, cell apoptosis and reactive oxygen species (ROS) levels were evaluated. Western blot and real-time polymerase chain reaction (PCR) were used to detect the protein and mRNA expression levels of B-cell lymphoma-2 (Bcl-2), Bcl-2-associated X protein (Bax), caspase-3, nuclear factor E2 related factor 2 (Nrf2), kelch-like ECH-associated protein 1 (Keap1), and heme oxygenase-1 (HO-1). The results showed that after being treated with 200 µmol/L H2O2 for 24 h, the survival rate of PC12 cells was 60.12%. Cytotoxicity experiments showed that nervonic acid could significantly reduce the contents of LDH and MDA, inhibit excessive production of ROS, and enhance the activities of SOD and GSH-Px in H2O2-injuried cells. In addition, it significantly upregulated the expression of Bcl-2, Nrf2 and HO-1, and downregulated the expression of caspase-3, Bax, and Keap1. In summary, nervonic acid has a protective effect on H2O2-induced oxidative damage in PC12 cells by a mechanism associated with the activation of the Nrf2/HO-1 signaling pathway.

In this study, an obese rat model induced by a high-fat diet (HFD) was used to investigate the modulating effect of 1-piperoylpiperidine (PIP) on circadian misalignment caused by metabolic dysregulation. The results showed that PIP attenuated HFD-induced liver injury, lowered blood lipid levels, alleviated circadian rhythm disruptionthe biological clock and lipid metabolism genes in the liver, and restored the changes in the expression of lysophosphatidic acid (16:0_18:1), bis-methyl phosphatidic acid (BisMePA, 38:8e), phosphatidyl ethanolamine (PE, 16:0p_22:6) and methylphosphocholine (MePC, 32:4e), which are closely associated with the biological clock. These findings may provide a theoretical basis for understanding the regulatory effect of PIP on the circadian rhythm of liver lipid metabolism.

In order to investigate the immunomodulatory effects of short-term administration of Cordyceps militaris on mice in different states and explore its application value as an immunomodulator, Kunming (KM) mice were randomly divided into a low-dose group (DB), a high-dose group (GB) and a control check group (CK). The mice in the DB and GB groups were continuously gavaged with different doses ofan aqueous suspension of C. militaris powder for 21 days, while the CK group was given the same dose of distilled water. Changes in body mass, organ indexes, serum immunoglobulin G (IgG), IgM, interleukin (IL)-2 and IL-10 levels, the percentages of CD3+CD4+ and CD3+CD8+ T lymphocyte subsets in peripheral blood, intestinal flora composition and Toll-like receptor (TLR)2, TLR4, myeloid differentiation factor (MyD) 88 and nuclear factor (NF)-κB expression in the jejunum were measured. Immunosuppressed mice induced by intraperitoneal injection of 80 mg/kg mb cyclophosphamide solution were intragastrically administered with C. militaris for 21 consecutive days. Immune indexes were detected after 0, 7, 14 and 21 days of administration. The results showed that administration of C. militaris at each dose did not cause significant changes in body mass, organ indexes, serum IgG, IgM, IL-2 and IL-10 levels or the percentages of CD3+CD4+ and CD3+CD8+ T lymphocyte subsets in the peripheral blood of mice (P > 0.05). C. militaris could up-regulate the Shannon index and the number of operational taxonomic units (OTU) in the intestinal flora of mice, and increase the diversity and richness of the intestinal flora. The relative abundances of the probiotics Lactobacillus and Alistipes were significantly increased (P < 0.05). The relative abundances of the inflammation-promoting bacteria Clostridium XIVa, Helicobacter and Lachnospiracea_incertae_sedis were significantly decreased (P < 0.05). The expression of TLR4 in jejunum tissues of mice was significantly decreased by all doses of C. militaris (P < 0.05), and the reduction of NF-κB expression was positively correlated with the dose of C. militaris. C. militaris significantly restored organ damage caused by cyclophosphamide in advance, increased the serum levels of IgM, IgG and IL-2 (P < 0.05), and promoted the proliferation of CD3+CD4+ and CD3+CD8+ T lymphocyte subsets in the peripheral blood of immunosuppressed mice. These results showed that short-term administration of C. militaris could reduce the risk of intestinal inflammation without causing an imbalance in the normal immune status. In conclusion, C. militaris can promote recovery from immunosuppression by enhancing humoral and cellular immunity and thus be developed and utilized as an immunomodulator.

A network pharmacological approach was used to predict active ingredients in apples that may have therapeutic effects on hemolysis-induced hyperbilirubinemia and their potential targets, enrichment pathways and action process and to construct adisease-pathway-active component-target network for apples. Autodock software was used to perform molecular docking of key active ingredients and potential targets to verify the reliability of the network analysis results. Furthermore, the effect of apple alcohol extract (AE) on hemolysis-induced hyperbilirubinemia in rats was explored. The results showed that 17 active ingredients of apples with high gastrointestinal absorption and excellent drug-like properties were selected, among which, quercetin, 2α-hydroxyl-ursolic acid, β-sitosterol, phloretin and epicatechin could make important contribution to the treatment of hemolysis-induced hyperbilirubinemia. The top 5 targets in terms of moderate values in the network, including the serine/threonine protein kinase (Akt1), vascular endothelial growth factor A (VEGFA), epidermal growth factor receptor (EGFR), the tyrosine kinase (SRC), and signal transducer and activator of transcription 3 (STAT3) could exert therapeutic effects through the bile secretion pathway, the hypoxia inducible factor (HIF)-1 signaling pathway, the tumor necrosis factor (TNF) signaling pathway and the nuclear factor-kappa B (NF-κB) signaling pathway. Molecular docking was performed on the major active ingredients and the core targets selected by the network, and the results showed a strong affinity between the active ingredients and the potential targets with reliable results from the network analysis. The animal experimental results indicated that compared with the blank control group, the model group had a significant decrease in hemoglobin (HB) levels in the blood and a significant increase in the levels of total bilirubin (TB), indirect bilirubin (IB), alanine transaminase (ALT), aspartate transaminase (AST), TNF-α, and interleukin-6 (IL-6) (P < 0.01). Compared with the model group, HB levels increased and while the levels of TB, IB, ALT, AST, TNF-α and IL-6 significantly decreased in the AE intervention and positive control groups (P < 0.05 or P < 0.01). In summary, apples reduce hemolysis-induced hyperbilirubinemia, which will provide a basis for research on non-invasive therapy for neonatal jaundice.

In order to clarify the mechanism underlying the regulatory effect of oxidative phosphorylation (OXPHOS) on the color stability of Tan sheep meat during postmortem storage, the M. longissimus dorsi of 6-month-old Tan sheep was stored at 4 ℃ after slaughter and evaluated for the activity of endogenous antioxidant enzymes and the content of reactive oxygen species (ROS) after 0, 4 and 8 days. Proteomics based on isobaric tags for relative and absolute quantitation (iTRAQ) was used to study protein expression in Tan sheep meat at different storage times. The results showed that during 0–8 days of storage, the activity of endogenous antioxidant enzymes showed a decreasing trend (P < 0.05), and the ROS content significantly increased with storage time (P < 0.05). Eight differentially expressed proteins were identified as the core proteins affecting the color stability of Tan sheep meat, namely ATP synthase F1 subunit alpha (ATP5A1), ATP synthase peripheral stalk subunit OSCP (ATP5O), ATP synthase peripheral stalk subunit D (ATP5H), cytochrome c oxidase subunit II (COX2), cytochrome c oxidase subunit 5A (COX5A), succinate dehydrogenase complex iron sulfur subunit B (SDHB), ADP/ATP translocase 1 (SLC25A4), and cytochrome c (CYCS). These proteins affected the color stability of Tan sheep meat mainly through the energy metabolism and redox processes. These results indicated that the loss of the activity of antioxidant enzymes in Tan sheep meat during postmortem storage caused the accumulation of ROS, which led to the destruction of the mitochondrial integrity of muscle cells and aberrant gene expression of complex subunits such as ATP5A1, ATP5O, ATP5H, COX2, COX5A, SDHB, SLC25A4 and CYCS in the oxidative phosphorylation pathway, thus contributing to changes in the structure and function of mitochondrial complexes and blockage of the oxidative phosphorylation process, and ultimately affecting the color stability of Tan sheep meat.

In order to explore the effect of heat shock treatment (HT) on the storage quality of fresh-cut lily bulbs, changes in the quality characteristics of lily bulb slices (Lilium davidii var. unicolor Cotton) exposed to heat shock treatment (hot water at 55 ℃, 2 min) were examined during storage at 4 ℃. The results demonstrated that HT effectively maintained the color of fresh-cut lily bulbs during storage and preserved the cell wall structure. The activities of peroxidase (POD), polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL) were suppressed by HT. Meanwhile, the accumulation of total phenolics (TP) and malondialdehyde (MDA) and the increase of relative electric conductivity (REC) were delayed, which led to reduced mass loss, decay rate, and browning degree. Comparison with the control group, the activities of POD, PPO and PAL in the HT group decreased by 95.26%, 21.74% and 41.65%, respectively. The decay rate, browning degree, MDA content, REC and TP content in the HT group were 10.56%, 1.55, 0.13 μmol/g, 19.71% and 3.51 mg/g, respectively, which were all significantly lower than those in the control group (P < 0.05), and the hardness, whiteness and soluble protein content were 1 848.09 g, 79.65 and 7.62 mg/g, respectively, which were all significantly higher than those in the control group (P < 0.05). After 40 days of storage, mass loss rates of 0.85% and 0.66% and soluble sugar contents of 14.04% and 14.78% were observed respectively for the control and HT groups, with no significant difference being found between the groups (P > 0.05). Furthermore, plasma membrane dissolution did not appear in the HT group until the 40th day, which was 30 days later than the control group. Therefore, HT effectively delayed the quality deterioration of fresh-cut lily bulbs during storage and prolonged the storage time.

The hindleg meat of Tan sheep was injected postmortem with the phosphoinositide 3-kinase (PI3K) inhibitor LY294002 at a concentration of 10 μmol/L and stored at 4 ℃. After 0, 2, 4, 6 and 8 days, the protein expression of PI3K and protein kinase B (AKT) was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot so as to verify whether the PI3K/AKT signaling pathway was effectively inhibited. Meanwhile, we analyzed changes in energy factors, oxidative stress levels, the degree of mitochondrial damage and cysteine aspastic acid-specific protease 3 (caspase-3) activity in order to explore the mechanism by which the PI3K/AKT signaling pathway induces the pathways of cell apoptosis during chilled storage of Tan sheep meat. The results showed that during storage, the protein expression levels of PI3K and AKT showed a decreasing trend, indicating that LY294002 inactivated the PI3K/AKT signaling pathway. Compared with the control group, LY294002 treatment significantly reduced mitochondrial ATP, glycogen content, succinate dehydrogenase (SDH) and citrate synthase (CS) activity (P < 0.05), gradually increased mitochondrial reactive oxygen species (ROS) levels, elevated the levels of oxidative stress and the opening of mitochondrial permeability transition pore (MPTP), significantly decreased membrane potential (P < 0.05), and significantly augmented the activity of caspase-3 (P < 0.05), indicating that the PI3K/AKT signaling pathway mediates the activation of downstream caspase-3 by promoting the production of ROS to interact with PI3K, damaging the structure and function of mitochondria, leading to the opening of MPTP and decreased membrane potential, and ultimately inducing cell apoptosis.

This study investigated the effect of salicylic acid (SA) treatment on preserving the color and nutritional quality of broccoli during postharvest cold storage. The results demonstrated that SA treatment significantly delayed the yellowing process, increased chlorophyll content, −a*/b* value, quantum yield (Fv/Fm), and fluorescence decline ratio (Rfd) and decreased L* value and yellowing index compared with untreated control. Meanwhile, the losses of glucoraphanin (GRA), glucobrassicin (GBS), sulforaphane (SFN), indole-3-methanol (I3C), and ascorbic acid (AsA) were obviously alleviated in the treated samples, and the accumulation of total phenols and total flavonoids was significantly increased. In addition, the total antioxidant capacity (T-AOC) of the treated samples was improved remarkably and the content of malondialdehyde (MDA) was significantly reduced. Multivariate statistical analysis visualized the distribution of sensory and nutritional variables in both groups of samples, further demonstrating that SA treatment was more effective in preserving GRA and AsA and effectively induced an improvement of the antioxidant capacity.

To solve the problem of the rapid softening of postharvest kiwifruit, the effect of 10 mmol/L N-acetyl-D-glucosamine (NAG) treatment on physiological changes, hexokinase (HXK) activity and AcHXKs gene expression in ‘Hongyang’ kiwifruit during postharvest ripening. The results showed that compared with the control group, exogenous NAG treatment could effectively inhibit the respiration rate and ethylene production of kiwifruit, delay the decline of firmness and total acid content, as well as the hydrolysis of starch and pectin, thereby maintaining a lower soluble solid content. In addition, NAG inhibited HXK activity and AcHXK3 expression level, thus affecting sugar and respiratory metabolism. Moreover, the expression of AcHXK7, 8 and 9 was upregulated, which was positively correlated with firmness and probably involved in glucose sensor-mediated postharvest softening of kiwifruit. In conclusion, NAG treatment can induce the differential expression of AcHXK3, 7, 8 and 9, thereby delaying kiwifruit postharvest ripening via catalytic and regulatory functions. These results may provide a theoretical basis for the mechanism of kiwifruit postharvest softening, and also help researchers develop novel strategies for kiwifruit preservation.

To explore the effect of slightly acidic electrolyzed water (SAEW) on the storage quality of postharvest chives, the changes in the microbial load and storage quality of postharvest chives subjected to SAEW immersion treatment at different concentrations (0, 100, 200 and 300 mg/L) for 5 minutes were analyzed during low temperature ((4 ± 1) ℃) storage. The results showed that immersion treatment with 200 mg/L SAEW was more effective in maintaining the organoleptic quality of chives and inhibiting the increase of the total number of colonies when compared with the other groups. Furthermore, 200 mg/L SAEW treatment was able to inhibit the increase of mass loss and rot rate, slow down the decrease of chlorophyll, vitamin C, soluble sugar, and soluble protein contents, and reduce the accumulation of total free amino acids, malondialdehyde (MDA) and nitrite in chives. It is evident that immersion treatment with 200 mg/L SAEW can not only effectively inhibit microbial growth on chives during low-temperature storage, but also effectively delay the loss of nutrients in chives, thus improving the quality preservation of chives. Therefore, SAEW can be used as an effective sterilization and preservation method to maintain the storage quality and delay the aging process of postharvest chives.

The pH value, glucose content, glycolytic potential, and expression levels of five glycolytic enzymes in lamb longissimus dorsi muscle at different time after slaughter were compared and analyzed, which treated at different cooling rates and stored at different temperatures. The impact of two steps in the process of ultra-fast chilling on the expression levels of glycolytic enzymes was determined. The regulatory mechanism of ultra-fast chilling on the glycolytic rate was elucidated from the perspective of protein expression. The results showed that ultra-fast chilling treatment significantly delayed the decrease of pH and the increase of glycolytic rate, promoted the expression levels of aldolase (ALDOA), glycogen phosphorylase (PYGM), and triosephosphate isomerase (TPI1), and inhibited the expression levels of phosphofructokinase (PFKM) and phosphoglycerate kinase (PGK). After cooling treatment, refrigeration and controlled freezing-point storage delayed glycolysis by inhibiting the expression level of PGK, without altering the effect of ultra-fast chilling. The expression level of PFKM was positively correlated with the rate of glycolysis at different temperatures. It was found that different glycolytic enzymes had different responses to temperature changes. Ultra-fast chilling affected energy supply and demand by changing the expression of enzymes involved in glycolysis. The high expression level of PFKM was associated with fast glycolysis. PFKM can be regarded as a key enzyme in the ultra-fast chilling process.

This study aimed to investigate the effect of different storage temperatures and methods for fresh tea leaves on the sensory quality, aroma components and biochemical components of broken black tea prepared from‘Yinghong 9’ tea leaves stored at 15, 25, 22–28 (room temperature) or 36–37 ℃ using sensory evaluation and headspace solid phase microextraction (HS-SPME) coupled to gas chromatography-mass spectrometry (GC-MS). The results showed that storage of fresh tea leaves at 15 ℃ could enhance the fresh and brick taste, sweetness and sweet volatile compound contents of broken black tea, which was more favorable to the formation of the quality of broken black tea. However, storage at 36–37 ℃ of fresh tea leaves could significantly affect the sensory quality and quality components of broken black tea. These results provide a reference for fresh tea leaf management and the quality improvement of black broken tea.

Three rapid visual methods, namely chromogenic, fluorescence and test strip, for the rapid detection of Burkholderia gladioli pv. cocovenenans in foods were established based on enzymatic recombinase amplification (ERA). Primers and probes were designed and screened based on the bonM gene of B. gladioli pv. cocovenenans. Then the specificity and sensitivity of the three methods were evaluated, as well as their applicability and accuracy in the detection of commercial food samples. The results showed that three strains of B. gladioli pv. cocovenenans, but not other common foodborne pathogens and other B. gladioli strains, were amplified by the three methods, indicating their good specificity. The detection limits of these methods were all 10-2 ng/μL, and their sensitivity was good. Out of 15 commercial samples, two tested positive by each of these methods with a detection rate of 13.3%. This result was consistent with that of the national standard method, indicating that our methods had good applicability and accuracy. All three methods give results that can be observed by the naked eye after amplification at 37 ℃ for 15 min, which provide a new and simple strategy for the rapid, visual and on-site screening of B. gladioli pv. cocovenenans in foods.

In order to make up for the misjudgment of fish freshness by colorimetry due to the unclear color distinction, a naphthol-benzothiazole derivative (HBO) was synthesized by the condensation reaction of naphthol as a fluorophore with benzothiazole salt. HBO could recognize organic amines by colorimetric and fluorescent responses, and allow nondestructive detection of salmon freshness. HBO showed an obvious response for all 12 amines tested in an EtOH/H2O (1:9, V/V) system, had a low limit of detection (0.4 μmol/L for spermine), and could image for spermine in living cells. The sensing gel HBO agarose gel (HBOAL) was prepared by loading the probe onto agarose gels. When salmon flesh is stored with HBOAL, the fish can be judged to be spoiled if HBOAL exhibits a light red color in daylight and a yellow color in ultraviolet light. HBOAL distinguished clearly among the three grades of salmon fish freshness with accurate evaluation results, and therefore could be used to monitor the freshness of salmon fish in real time.

An analytical method using ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was established for the detection of 59 illegally added drugs in health foods with hypoglycemic, hypolipidemic and antihypertensive activity. Samples were extracted with methanol, and the extract was purified by the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method and blown to dryness under nitrogen gas. The residue was dissolved in 1 mL of 40% (V/V) methanol aqueous solution. The chromatographic separation was performed using reverse-phase chromatography on an ACQUITY UPLC HSS T3 column through gradient elution using a mobile phase consisting of acetonitrile and 0.1% aqueous formic acid (containing 5 mmol/L ammonium acetate). The mass spectrometer was operated in both the positive and negative ion modes using multi-reaction monitoring (MRM), and quantitative analysis was performed using a matrix-matched external standard method. The results showed that the calibration curves for the 59 illegally added drugs were linear with coefficient of determination (R2) greater than 0.980. Recoveries ranged from 60.2% to 119.5%, and relative standard deviations (RSDs) ranged from 1.2% to 15.0%. This method is characterized by simple pre-treatment, short analysis time, good sensitivity, high accuracy, and low impurity interference, and can be used to the detection of multiple illegal drugs in health foods with hypoglycemic, hypolipidemic and antihypertensive activity.

Human milk is the most important source of nutrition in early infancy, which can meet all the nutritional needs in the first 6 months after birth. It contains many bioactive substances that can regulate the intestinal flora, promote the development of the immune system, and enhance the intestinal barrier. Human milk oligosaccharides (HMOs) are one of the active substances in human milk. They cannot be directly digested and absorbed by infants, but can be used as a prebiotic to stimulate the establishment and evolution of the gut microbiota. Bifidobacterium longum subsp. infantis is a dominant microorganism in the gut of breastfed infants, which has almost all gene clusters required for metabolizing the major HMOs, and its interaction with HMOs plays a key role in the early intestinal health of infants. This review summarizes the composition and structure of HMOs, describes the utilization of HMOs by B. longum subsp. infantis and summarizes the beneficial effects B. longum subsp. infantis exerts in infants by metabolizing HMOs, which will lay the foundation for exploring the interaction mechanism between HMOs and the gut microbiota, as well as its role in infant intestinal development and maturation.

Obesity has become a serious threat to human health, with excessive intake of sugar being one of the major causes of obesity. Therefore, replacing high-calorie sugar with low-calorie functional sweeteners or sugar substituents is a popular dietary choice for the prevention and management of obesity. However, the relationship between functional sweeteners and obesity is complex, and no definitive conclusion has been reached. This is because the effect of functional sweeteners is influenced by various factors, including the type and dosage of functional sweetener, as well as individual differences such as gender, health status and gut microbiota composition. In this article, we review the effect of common functional sweeteners on energy metabolism, fat metabolism and the gut microbiota in the body. Furthermore, we summarize the current studies on the effect and mechanism of functional sweeteners on obesity hoping to provide a reference for better selection or application of foods and beverages containing non-nutritional sweeteners in the future.

Carbohydrates play a vital role in food science, medicine science, life science and other fields. Carbohydrates can be divided into monosaccharides, oligosaccharides, and polysaccharides, among which monosaccharides and oligosaccharides are mostly soluble, which can not only serve as structural substances, but also have various biological activities such as antioxidant, anticancer, antibacterial, and antiviral activities. Hydrophilic interaction chromatography makes up for the deficiency of reversed-phase liquid chromatography in the separation of carbohydrates. This paper reviews the stationary phases including amino bonded stationary phase, amide bonded stationary phase, carbohydrate bonded stationary phase and zwitterionic bonded stationary phase used in hydrophilic interaction chromatography for the separation and analysis of monosaccharides and oligosaccharides during 2017­–2022, and summarizes the effects of chromatographic separation conditions such as acetonitrile content, buffer salt concentration, mobile phase pH and column temperature on the hydrophilic separation efficiency so as to provide a reference for the separation and analysis of monosaccharides and oligosaccharides.

In recent years, researchers have often modulated the sensory and functional properties of foods through the interaction among various food components. Phenolic acids, proteins and carbohydrates widely exist and play important roles in flour products. Until now, existing studies primarily concentrate on the interactions of phenolic acid with protein and carbohydrate, along with their applications in several fields such as food processing and healthcare. The intricate interactions in the phenolic acid-protein-carbohydrate ternary system impart different sensory and functional properties to flour products. In this article, we review the research progress on the interactions among phenolic acid, protein and carbohydrate and their influence on the sensory and functional properties of bread dough, hoping to provide theoretical guidance for the application of the ternary system composed of phenolic acids, proteins and carbohydrates in flour products.

Liver is one of the important edible byproducts of livestock and poultry. It has high nutritional value and a long history of human consumption in China. However, liver, when used as food, has the problems of off-flavor, poor texture, and high risk of residual harmful substances, which results in low overall food utilization rate. This not only reduces the overall profit of the meat processing industry, but also causes a waste of resources. This review focuses on recent research on the nutrition, flavor, texture, and quality improvement of livestock and poultry liver. Moreover, the defects and blind spots in current research are summarized. It is expected that this review will be helpful for further research and provide a basis for the high-value utilization of livestock and poultry liver.

Plant essential oils, which can effectively extend the shelf life of fruits and vegetables, possess antioxidant, antibacterial and insect repellent properties, demonstrating them as promising natural preservatives for fruits and vegetables. However, the applications of plant essential oils in fruit and vegetable preservation are limited due to their disadvantages such as high volatility, poor stability and weak hydrophilicity, as well as strong aroma. Stable plant essential oil delivery systems that can form a barrier to the external environment provide new methods and approaches to overcome these limitations. In addition, the delivery systems can improve biocompatibility and have controllable release function, thus enhancing the utilization rate of plant essential oils. In the present paper, we review the composition, antioxidant, antibacterial and insect repellent activity and mechanisms of action of plant essential oils, and summarize various delivery systems including nano-emulsions, microemulsions, microcapsules, and liposomes and their preparation methods, and discuss the major factors affecting the encapsulation efficiency, particle size and physical stability of plant essential oils such as preparation methods, emulsifiers, the type and concentration of wall material. Finally, we summarize the applications and prospects of delivery systems for plant essential oils in fruit and vegetable preservation with the aim of providing a theoretical foundation for the development of new, effective fruit and vegetable preservatives.

Fucoidan-degrading enzymes are glycoside hydrolases that hydrolyze fucoidan into low molecular mass fucosan with biological activity or other products. The enzymes have great application value in the preparation of active fucoidan oligosaccharides, biopharmaceutics and disease diagnosis. In this article, the sources, properties, modes of action, structures and applications of fucoidan-degrading enzymes are reviewed, revealing that fucoidan-degrading enzymes are mainly derived from marine microorganisms and marine invertebrates and that the enzymatic properties, substrate specificity, molecular structures and catalytic mechanisms of fucoidan-degrading enzymes vary significantly depending on the species source. Different types of fucoidan-degrading enzymes catalyze different sites of complex fucoidans producing fucoidan oligosaccharides with antioxidant, anti-tumor, anti-thrombotic or other special activities. Therefore, the utilization of fucoidan-degrading enzymes in the preparation of drugs and functional foods has gradually become a research focus in the application field of polysaccharides. This article provides theoretical support for further research on fucoidan-degrading enzymes, and also provides references for the effective development of fucoidan oligosaccharides with special biological functions.

In the Chinese strong-flavor baijiu (CSFB) fermentation ecosystem, the caproic acid-anabolism of caproic acid-producing bacteria (CPBs) is very important for improving the fermentation quality of CSFB. Therefore, it is necessary to thoroughly understand the types of CPBs and their caproic acid-anabolism characteristics. This minireview introduces readers to the diversity, phylogenetic relationship, physiological and metabolic characteristics, and caproic acid synthesis mechanism of CPBs isolated from the CSFB fermentation ecosystem as well as their synergistic metabolic relationships with other CPBs or non-CPBs. This paper provides a reference for understanding the in-situ caproic acid-anabolism pattern of CPBs from the CSFB fermentation ecosystem, and further provides a theoretical basis for the future targeted application of CPBs in CSFB fermentation and for CPBs culture engineering for the synthesis of high value-added caproic acid.

Sweeteners cannot completely replace the satisfaction provided by sugars, even though they offer a similar flavor perception and much higher sweetness intensity than sugars. Clarifying the biological mechanism of this phenomenon is important to improve the functional evaluation system for sweeteners and promote sweetener innovations. Herein, we review the research progress on the difference in the behavioral preferences of animals, the activity of brain regions and the activation patterns of the gut-brain axis induced by sugars and sweeteners, and we uncover the underlying reason why the brain distinguishes sugars from sweeteners, causing differences in individual behavioral preferences. Moreover, we propose that animal behavior, neural activity in brain regions, and the capacity to activate key receptors can be used to evaluate the gut-brain axis effects of sweeteners, which will provide a reference for innovative developments in the field of sweeteners.

Hyperuricemia (HUA) is a purine metabolism disorder caused by the imbalance between uric acid production and excretion, which, when severe, can lead to gout and renal function damage. At present, the prevalence of HUA/gout is increasing yearly in China and the HUA/gout patients are becoming younger and younger. Recent studies have shown that the intestinal flora of patients with HUA/gout is imbalanced when compared with that of healthy people, and different dietary patterns can affect the level of uric acid by adjusting the intestinal flora. This paper elaborates on the characteristics of the intestinal flora in patients with HUA/gout and the effect of the intestinal flora on uric acid metabolism, which will lay a theoretical foundation for the prevention, early diagnosis and auxiliary treatment of HUA/gout. This paper also summarizes recent progress in understanding the impact of different dietary patterns on uric acid levels in order to guide patients to effectively prevent and delay the occurrence of HUA/gout by adjusting their dietary patterns.