In order to explore the superior eating quality of Wuchang rice, the preference ranking test and a modified version of Rate-All-That-Apply (RATA) were used to study the differences in the overall preference and sensory attributes between rice from different townships in Wuchang city and between Wuchang rice and rice from other regions. Principal component analysis (PCA) and classification and regression tree (CART) were combined to classify rice from different regions. The results showed that rice from different regions had different sensory characteristics. Wuchang rice had a sweet and clean taste, smooth and elastic texture, and strong aroma. Its eating quality was significantly superior to that of rice from other regions. A total of 12 sensory attributes including appearance (fullness, completeness, and looseness), odor (rice-like, clean aroma), taste (sweetness and sweet aftertaste), and texture characteristics (stickiness palatability, softness/hardness, elasticity, smoothness and delicacy) were identified as the key sensory attributes to discriminate among rice from different regions. This study provides a theoretical basis and reference for the establishment of a sensory evaluation system for Wuchang rice.

In order to improve the added value of walnut, walnut glutelin peptides (WGPs), which were prepared from walnut meal, were chelated with zinc ions. The zinc chelating characteristics of WGPs were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) spectroscopy. The peptides were screened for zinc binding capacity by ultrafiltration, gel column chromatography and liquid chromatography-tandem mass spectrometry (LC-MS/MS), and the specific binding sites and binding capacity of the peptides were explored by molecular docking. The results showed that WGPs could chelate with zinc ions, leading to significant alterations in the surface microstructure and crystallinity of the peptides. After ultrafiltration and gel column chromatography, fraction F41, which had the highest chelating capacity of (117.43 ± 1.99) mg/g, was obtained. By LC-MS/MS combined with virtual screening, five potential bioactive peptides without toxicity or allergenic potential were identified. Molecular docking was used to simulate and analyze the binding process. It was found that pentapeptide Phe-Asp-Ala-Asp-Phe (FDADF) could form a structurally stable complex with zinc ions through coordination bonds, hydrogen bonds and hydrophobic interactions. Among the five peptides, the pentapeptide exhibited the lowest binding energy (−7.27 kcal/mol), and the main binding site was the carboxyl oxygen atom (Asp4:O-Zn) of the aspartic acid (Asp) side chain. This study provides a theoretical basis for the development and application of zinc-chelating peptides.

In this study, a water-in-oil-in-water (W1/O/W2) multiple emulsion stabilized by dextran-ferritin-resveratrol (Dex-rHuHF-Res) nanoparticles was prepared by a two-step emulsification method. Its stability and potential for the delivery of bioactive substances were analyzed. The results showed that when the concentration of polyglycerol ricinoleate (PGPR) was 7% (V/V), the ratio of aqueous phase (W1) to oil phase (O) was 3:7, and the ratio of W1/O to outer aqueous phase (W2) was 4:6, the emulsion had homogeneous appearance, uniform droplet size distribution, the smallest particle size (472 nm), and the highest apparent viscosity and storage modulus (G’). At pH 7, 100 mmol/L NaCl concentration and low centrifugal force, the emulsion maintained good stability. In unfavorable environment, compared with free chlorogenic acid, astaxanthin and resveratrol, the retention rates of chlorogenic acid, astaxanthin and resveratrol loaded in the multiple emulsion were significantly improved (P < 0.05). The bioaccessibilities of chlorogenic acid, astaxanthin, and resveratrol loaded in the W1/O/W2 emulsion were significantly increased (P < 0.05), and the antioxidant property of the emulsion was obviously enhanced (P < 0.05). This study provides a theoretical basis for the application of the W1/O/W2 emulsion stabilized by Dex-rHuHF-Res nanoparticles in the delivery of active substances.

Tilapia fillets rinsed in ozone water were made into surimi, and the effects of ozone water concentration and rinsing time on the quality and in vitro digestive properties of surimi were investigated. Furthermore, the mechanism by which ozone water rinsing improved the quality of tilapia surimi was investigated by analyzing the degree of myofibrillar protein oxidation. The results showed that the whiteness, hardness and gumminess of surimi were significantly increased by ozone water rinsing (P < 0.05), and the surimi rinsed with 10 mg/L ozone water for 10 min had the best gel properties. With the increase in ozone water concentration and rinsing time, the thiobarbituric acid reactive substances (TBARS) value of surimi tended to increase, and the carbonyl content of myofibrillar proteins increased and the total sulfhydryl content gradually decreased. The sensory evaluation results showed that the best sensory quality was obtained by rinsing with 10 g/mL ozone water for 10 min. sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that rinsing with 10–18 mg/L ozone water caused the proteins to cross-link and form small soluble aggregates, while ozone water at concentrations more than 18 mg/L caused the formation of large insoluble aggregates. According to Raman spectra, after rinsing with 10–18 mg/L ozone water, the secondary structure of myofibrillar proteins was gradually unfolded, and the α-helix was gradually converted to β-sheet and random coil. Ozone water rinsing increased the degree of hydrolysis of surimi during in vitro digestion, the highest being observed with 10 mg/mL ozone water rinsing for 10 min. The content of small peptides (100–1 000 Da) after digestion was significantly higher than that of the other experimental groups (P < 0.05). In conclusion, moderate oxidation of myofibrillar proteins could improve the quality of tilapia surimi, and the surimi rinsed for 10 min in 10 mg/mL ozone water had the highest sensory quality and the best gel characteristics and in vitro digestive characteristics.

In this study, whole genome sequencing of Bacillus velezensis L-39, an extracellular polysaccharide-producing strain isolated from Pixian Douban, was carried out through the combined use of second-generation Illumina HiSeq and third-generation PacBio platforms. The genomic analysis covered gene assembly, prediction, annotation, and the elucidation of secondary metabolite biosynthetic gene clusters and crucial gene functions, focusing on the gene clusters for carbohydrate metabolism, the nucleoside sugar synthesis pathways, and extracellular polysaccharide biosynthesis. The results showed that the whole genome size of B. velezensis L-39 was 3 970 591 bp in length, encoding a total of 3 770 genes. Through Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, the eps gene cluster and 32 functional genes were predicted from the genome, and a complete extracellular polysaccharide (EPS) synthesis pathway was mapped. Subsequently, polymerase chain reaction (PCR) was performed on the pivotal genes, with results expected. The aim of this study is to discover genes closely related to extracellular polysaccharide synthesis by B. velezensis L-39 in order to provide a scientific foundation for an in-depth analysis of the molecular basis for extracellular polysaccharide production by this strain and for its practical application and development.

To dissect the bacteriocin gene clusters of Lactiplantibacillus plantarum CHEN1, which has a significant inhibitory effect on methicillin-resistant Staphylococcus aureus (MRSA), the whole genome of CHEN1 was sequenced using PacBio RS and Illumina platforms. antiSMASH and BAGEL4 were used to predict bacteriocin gene clusters and explore their potential action mechanisms. The whole genome sequencing results revealed that the genome of L. plantarum CHEN1 was 3 330 435 bp in size, with a GC content of 44.34%, including one chromosome sequence and eight plasmids. It contained 3 196 protein-coding genes, with 704, 2 317 and 2 775 genes being annotated in the Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and Cluster of Orthologous Groups of proteins (COG) databases, respectively. The genome sequencing data were submitted to NCBI under GenBank accession number PRJNA1014938. Three bacteriocin-related gene clusters, T3PKS, RiPPs and Class IIb bacteriocins, were predicted by antiSMASH and BAGEL4, meeting the prerequisites for bacteriocin expression. This study provides a bioinformatic foundation for the development and application of CHEN1 and its MRSA-inhibiting bacteriocin.

In order to explore the source of fermenting microorganisms in pickled Chinese cabbage, this study used high-throughput sequencing and bioinformatics techniques to investigate the diversity of microbial community in the fermented juices of raw and cooked Chinese cabbage at the early stage of fermentation and the diversity of total and culturable endophytic bacteria in Chinese cabbage. The results showed that at the phylum level, most of the bacteria in the fermented juices of raw and cooked Chinese cabbage were the same as the endophytic bacteria of Chinese cabbage. Four lactic acid bacteria genera were annotated in each of the fermented juices, namely Lactococcus, Leuconostoc, Lactobacillus, and Weissella, and 299 genera including 6 lactic acid bacteria genera were annotated in the endophytic bacteria. The lactic acid bacteria genera induced four ones common to both fermented juices as well as Bifidobacterium and Tetragenococcus, indicating that the endophytic bacteria were one of the sources of lactic acid bacteria in pickled Chinese cabbage. Compared with pickled raw Chinese cabbage, the number and relative abundance of pathogenic bacteria genera annotated in pickled cooked Chinese cabbage were significantly reduced, and most of the pathogenic bacteria genera detected belonged to the pathogenic endophytic bacteria genera in Chinese cabbage. Among the 51 culturable endophytic bacterial genera identified on plates, three lactic acid bacteria genera were also found in pickled Chinese cabbage.

This study aimed to investigate the degradation of myofibrillar protein (MP) and sarcoplasmic protein (SP) during the fermentation of shrimp meat with Enterococcus lactis as well as the changes in antioxidant activity of the degradation products (peptides). The findings revealed that for both protein extracts, the pH significantly decreased with fermentation time (P < 0.05), and the protease activity significantly increased (P < 0.05) compared to that before fermentation. The results of gel electrophoresis showed that the fermentation resulted in degradation of both proteins, with more pronounced degradation of SP being noted compared to MP. The scavenging capacity against 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical as well as Fe3+ reducing power of the two protein extracts were significantly enhanced after the fermentation (P < 0.05), and the antioxidant capacity of the peptides derived from SP was significantly higher than that of the peptides derived from MP (P < 0.05). Correlation analysis showed a significantly positive correlation (P < 0.05, and P < 0.01) between protease activity and the degree of SP hydrolysis and the antioxidant activity of its degradation products. The results of this study indicated that peptides with high antioxidant capacity could be obtained from fermented shrimp proteins with E. lactis, and the peptides derived from SP had higher antioxidant activity. This study provides a theoretical basis for the full utilization of sarcoplasmic proteins produced during aquatic products processing (e.g. surimi) and the development of antioxidant peptides.

Strain S10, isolated from the intestine of Apostichopus japonicus, is able to produce alginate lyase at a high yield. In order to scrutinize its genome sequence and to explore gene resources related to alginate lyase, strain S10 was identified through morphological observation and 16S rRNA sequence analysis. Then, its whole genome was sequenced using Illumina second-generation sequencing technology and PacBio, the third-generation high-throughput sequencing platform. The sequencing data were used for genome assembly, gene prediction, and gene function annotation. In addition, based on the annotation results, bioinformatics analysis and structure prediction were performed on three sets of putative alginate lyase gene sequences in strain S10. The results showed that strain S10 was identified as Vibrio alginolyticus, with a total genome length of 5 397 046 bp and a GC content of 44.59%. The genome was composed of two chromosomes and one plasmid. A total of 4 936 protein-coding genes, 127 tRNA genes and 37 rRNA genes were predicted. Totally 4 039, 3 163, 3 104 and 96 functional genes were annotated in the Clusters of Orthologous Groups (COG), Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and Carbohydrate-Active EnZymes (CAZy) databases, respectively. In addition, three groups of potential alginate lyase genes, alg4755, alg4756 and alg4760, were found in strain S10. Bioinformatics analysis showed that alginate lyases Alg4755, Alg4756 and Alg4760 all belonged to the polysaccharide lyase family 7 (PL7) and had three highly conserved motifs of the PL7 family, R*E*R, Q(I/V)H and Y*KAG*Y*Q. In summary, the sequencing and analysis of the whole genome of S10 strain is of great significance for understanding the mechanism of efficient enzyme production by this strain and for exploring new alginate lyases, and also provides a theoretical basis for follow-up research on enzyme expression and industrial application.

This study aimed to prepare copper-chelating peptides from soybean meal (SBMP-Cu(II)) using Aspergillus oryzae in solid-state fermentation and to investigate the chelation mechanism, structure and stability of SBMP-Cu(II). The results showed that peptides from soybean meal peptides (SBMP) with molecular masses of 1–5 kDa had a strong chelating capacity toward Cu2+, and the Cu2+ chelating capacity reached up to (288.47 ± 2.18) mg/g after purification by weak anion-exchange chromatography and gel filtration chromatography. A total of 27 oligopeptides with molecular masses of less than 1 500 Da were identified from the 1–5 kDa SBMP by liquid chromatography-tandem mass spectrometry (LC-MS/MS), and acidic (aspartic acid and glutamic acid) and basic amino acids (arginine, histidine and lysine) played a key role in the chelation of Cu2+. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and zeta potential analysis showed that the major active groups in SBMP involved in its chelation with Cu2+ were –COOH and –NH2, and SBMP-Cu(II) had a higher crystallinity, with the formation of roughly spherical agglomerates caused by the neutralization of charges on the surface. In addition, SBMP-Cu(II) showed stronger resistance to acid, heat and salt as well as higher in vitro digestive stability than SBMP, suggesting that SBMP-Cu(II) has the potential to improve Cu2+ bioavailability as a new copper supplement. These results provide a theoretical basis and technical support for the low-cost and efficient preparation of SBMP-Cu(II) supplements and the high-value resource utilization of soybean meal.

In this work, the probiotic properties of Lacticaseibacillus paracasei K56 were examined by measuring its ability to tolerate gastrointestinal fluids and its adhesion characteristics. Additionally, the role of its surface proteins in mediating intestinal cell adhesion was investigated by laser confocal microscopy (LCM) and liquid chromatography-mass spectrometry (LC-MS). After 3 h of incubation in artificial gastric fluid, the survival rate of L. paracasei K56 was (88.78 ± 3.31)%, but increased to (91.57 ± 2.24)% when it was transferred into intestinal fluid and further cultured for 2 h. It possessed strong bacteriostatic activity, antioxidant capacity, and good gastrointestinal tolerance. The surface hydrophobicity of L. paracasei K56 toward xylene was (26.24 ± 0.53)%, and the self-polymerization capacity after 5 h was (28.47 ± 1.19)%. Removal of surface proteins decreased the adhesion of L. paracasei K56 to mucin, collagen, and Caco-2 cells. LC-MS analysis identified LPXTG-motif proteins and moonlighting proteins as some of the surface proteins of L. paracasei K56. It was hypothesized that L. paracasei K56’s surface proteins were crucial to the adhesion process, mediating specific adhesion to intestinal epithelial cells and extracellular matrix. The findings of this study offer a theoretical foundation for future research on the utilization and development of L. paracasei K56 in dietary supplements and dairy manufacturing.

Objective: To investigate the regulatory effect of soybean-derived exosome-like nanovesicles (SELNs) on lipid metabolism in Caenorhabditis elegans. Methods: SELNs were isolated and purified from soybean by ultracentrifugation combined with sucrose density gradient centrifugation. The composition of SELNs was analyzed. The stability of SELNs to in vitro digestion was evaluated. The effects of SELNs (1–100 μg/mL) on the content of lipid droplets in hyperlipidemic C. elegans induced by sodium palmitate (SP) were monitored by two staining methods for neutral lipids: Nile red (NR) and oil red O (ORO), and the content of triglyceride (TG) was determined. The effects of SELNs on the expression of key genes associated with lipid metabolism in C. elegans were analyzed by polymerase chain reaction (PCR). Results: SELNs were rich in lipid, protein and nucleic acid. The structure of SELNs was stable in the stomach acid environment but was broken in the intestinal fluid. SELNs inhibited the formation of lipid droplets induced by SP, significantly down-regulated the abnormal increase in the relative mRNA expression of fat-5, fat-6 and fat-7 induced by SP, and up-regulated the relative mRNA expression of aak-2. Meanwhile, SELNs significantly up-regulated and down-regulated the relative expression of daf-2 and daf-16, respectively. Conclusion: Moderate intake of SELNs can regulate the expression of key genes associated with lipid metabolism, inhibit lipid droplet generation, and consequently reduce lipid deposition.

Objective: To investigate the anti-aging effect of camel milk immunoglobulin G (IgG) at different concentrations (0.25, 0.5, 1, 2, and 4 mg/mL) on the model organism Caenorhabditis elegans. Methods: The anti-aging activity of camel milk IgG was evaluated by analyzing the lifespan, reproductive capacity, locomotory capacity, stress resistance, and lipofuscin level of C. elegans. Results: Compared with the control group, the concentration of IgG in camel milk was safe, which damaged neither the reproductive nor locomotory capacity of C. elegans. Feeding of camel milk IgG at concentrations of 1, 2, and 4 mg/mL significantly prolonged the average lifespan of C. elegans, and at 0.5 and 4 mg/mL significantly increased the swallowing frequency (P < 0.05). Feeding of camel milk IgG at 0.25, 0.5 and 1 mg/mL significantly improved the heat stress resistance, and significantly prolonged the average lifespan of C. elegans (P < 0.05). Feeding of camel milk IgG at 1 and 4 mg/mL significantly increased the oxidative stress resistance of C. elegans (P < 0.05), and lipofuscin deposition was significantly decreased after 14-day feeding of camel milk IgG at 0.5 and 2 mg/mL (P < 0.05). Conclusion: Feeding a certain concentration of camel milk IgG has an anti-aging effect on C. elegans.

Objective: To study the ameliorative effect and mechanism of alginate oligosaccharides (AOS) on NG-nitro-L-arginine methyl ester (L-NAME)-induced hypertension in mice. Methods: AOS was used as a preventive treatment for hypertensive mice for 6 weeks. Blood pressure of the mice was monitored, pathological changes in kidney, heart and aortic tissues were observed and the level of oxidative stress was measured. Furthermore, serum levels of total antioxidant capacity (TAC), nitric oxide, angiotensin II, and endothelin-1 were measured, and the protein expression of endothelial nitric oxide synthase (eNOS) in the aorta was also detected. Results: AOS (1.5 g/kg body weight) effectively reduced the systolic blood pressure value of 22.4 mmHg in L-NAME-induced hypertensive mice, and significantly ameliorated pathological changes and oxidative stress injury in the kidney, heart and aorta. Compared with the model group, the serum levels of blood urea nitrogen, creatinine, uric acid, lactate dehydrogenase activity, creatine kinase activity, angiotensin II and endothelin-1 in AOS-treated mice were reduced by 38.0%, 46.5%, 45.2%, 15.9%, 46.4%, 29.5%, and 26.2%, respectively, and serum TAC and nitric oxide concentration were increased by 24.1% and 246.5%, respectively. Furthermore, the protein expression of eNOS in the aorta was significantly increased by 152.9%. Conclusion: AOS has a hypotensive effect in mice, which can inhibit oxidative stress and ameliorate vascular endothelial dysfunction induced by hypertension. This study provides a scientific basis for the potential of AOS as a functional food ingredient for antihypertension.

In this study, theabrownin from Liupao tea was extracted and separated into extractable (FTB) and non-extractable (BTB) fractions using methanol. The composition of the two fractions was analyzed by Fourier transform infrared (FTIR) spectroscopy, sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE), Western blot, and ultra-high performance liquid chromatography-high resolution mass spectrometry (UPLC-HRMS). The study found that the theabrownin was a polyhydroxyl aromatic compound complexed with nitrogen compounds, including proteins, amino acids, and peptides. Electrophoresis showed two protein bands with molecular masses ranging from 63 to 75 kDa, which were generally diffuse long strip-shaped and may be modified by polyphenols and other substances. Non-targeted metabolomics identified 297 compounds. A total of 137 significantly differential compounds between FTB and BTB were selected using the cutoff of fold change (FC) > 2 or FC < 0.5 and P < 0.05, the major ones being phenolics (37). Principal component analysis (PCA) and orthogonal partial least squares-discriminant analysis (OPLS-DA) revealed that catechin, 2,3-dihydroxybenzoic acid, gallic acid, 4-hydroxycoumarin, and caffeic acid could be used to discriminate between FTB and BTB and may be the major non-extractable phenolics of theabrownin. This study contributes to the understanding of protein-polyphenol complexes in dark tea and encourages further research of the composition and functional activity of theabrownin in dark tea.

This study aimed to evaluate the characteristic aroma compounds of white tea made from ‘Fuhuang 1’, an albino mutant of ‘Fuandabaicha’, and their dynamic changes during tea processing. The types and relative contents of volatile compounds in ‘Fuhuang 1’ and ‘Fuandabaicha’ tea leaves withered for 0, 12, 24, 36 and 48 h and in white tea made from each variety were determined by headspace solid-phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS). A total of 560 aroma compounds were detected in all samples, among which terpenes, heterocyclic compounds, esters and hydrocarbons were the major aroma components of white tea. During the withering process, the total content of volatile metabolite in both cultivars gradually increased, reaching the highest value at 48 h. Based on their relative odor activity values (ROAVs), terpinolene, citral, 1-octen-3-one, and damascenone were identified as the key aroma components of ‘Fuandabaicha’ white tea, and these compounds together with methyl salicylate and benzaldehyde as the key aroma components of ‘Fuhuang 1’ white tea. 1-Octen-3-one and citral were accumulated in large amounts at the early stage of withering and then decreased. Terpenolene, benzaldehyde, methyl salicylate, and damascus ketone continuously increased during the whole withering process. Terpinolene, citral, 1-octen-3-one, and damascenone greatly contributed to the floral, fruity and sweet aroma of ‘Fuhuang 1’ and ‘Fuandabaicha’ white tea. 1-Octene-3-one, methyl salicylate, and benzaldehyde were the key compounds responsible for the clean and fresh aroma of ‘Fuhuang 1’ white tea. This study helps gain insights into the aroma characteristics of ‘Fuhuang 1’ white tea and provides a scientific basis for the research and development of white tea made from albino tea plant mutants.

In this study, headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) and odor activity value (OAV) techniques were used to investigate the effects of catalase and/or polyphenol oxidase on the aroma components in instant Baiyaqilan tea powder. The results showed that all three enzymatic treatments led to significant changes in the types and contents of aroma components in Baiyaqilan instant tea powder. Catalase treatment resulted in the highest amount of aroma components and the highest increase in OAV, as well as the formation of new compounds such as trans-linalool oxide (furanose), cis-caproic acid-3-hexenyl ester and trans-β-farnesene, and it significantly increased the OAV of trans-2-nonenal, β-cyclocitral, trans-2-decenal and trans-geranylacetone when compared with untreated tea samples. Polyphenol oxidase treatment led to the formation of new compounds such as cis-3-hexenyl hexanoate, trans-β-farnesene, trans-β-ionone and β-epoxyviniferone, and significantly increased the OAVs of trans-2-nonenal, linalool and trans-β-ionone. The combined treatment group contained the greatest number of aroma components, including the newly formed compounds cis-3-hexen-1-ol, trans,trans-2,4-heptadienal, cis-β-ocimene, trans-2-octenal, trans,trans-3,5-octadien-2-one, nonanal, 5-ethyl-6-methyl-3-hepten-2-one, hexyl butyrate, Z-3-hexenyl valerate, hexyl 2-methylbutanoate, cis-hexanoic acid-3-hexenyl ester, hexyl hexanoate, trans-β-farnesene and trans-β-ionone, and showed a significant increase in the OAV of linalool. The mechanisms behind the changes in the aroma of instant Baiyaqilan tea powder induced by polyphenol oxidase and/or catalase treatments might be related to oxidative degradation of carotenoids, lipid peroxidation, and glycosidic bond rupture of terpene alcohol precursors. This study reveals a synergistic effect of combined treatment with catalase and polyphenol oxidase on the aroma of instant Baiyaqilan tea powder, which provides an important basis for improving the aroma quality of instant tea powder.

This study employed non-targeted metabolomics combined with chemometrics to investigate the effects of different manufacturing processes, harvest times and cultivation methods on the key characteristic components of Liudong tea, a specialty tea cultivar from Guangxi. A total of 23 key components were identified, including (+)-gallocatechin and theaflavinmonogallates. Among them, catechins and their derivatives, as well as flavonoids, predominated, accounting for 82.6% of the total. The key characteristic components with the highest variable importance in the projection (VIP) values for distinguishing Liudong tea from different processing methods and harvest times were terpenes and their derivatives, namely acuminoside@RT 9.77 and (+/-)-sabinene@RT 10.11, while that for distinguishing Liudong tea from different cultivation methods was (+)-catechin. The results indicated that different processing methods, harvest times and cultivation patterns significantly influenced the key characteristic components and their content distribution in Liudong tea. The black tea processing method promoted the formation of theaflavinmonogallates and the hydrolysis of terpenoid glycosides. The later the harvest date, the higher the relative abundance of five key flavonoid components, including kaempferol-3-O-(6’’’-trans-p-coumaroyl-2’’-glucosyl) rhamnoside. Artificial cultivation reduced the relative abundance of some key characteristic components including catechins such as (+)-catechin and their derivatives. This study contributes to understanding the mechanisms underlying the formation of the characteristic quality of different Liudong tea, thereby providing a scientific basis for improving the cultivation techniques and processing methods for the quality control of Liudong tea.

In this study, the effect of catalase on the transformation of aroma components in Baiyaqilan tea, a new type of oolong tea was investigated by gas chromatography-mass spectrometry (GC-MS) and odor activity value (OAV). The results showed that the types of volatile aroma components in Baiyaqilan tea changed after catalase treatment. A total of 17 and 23 components with OAV ≥ 1 were identified in Baiyaqilan tea before and after catalase treatment, respectively. Principal component analysis (PCA) performed on the aroma composition data showed a good discrimination between Baiyaqilan tea before and after catalase treatment. The OAV of aroma components such as trans-2-nonenal, linalool, trans-geranylacetone, and β-cyclocitral increased significantly after catalase treatment, while those of cis-linalool oxides decreased significantly. The changes of these components indicated that the effect of catalase on the aroma of Baiyaqilan tea was related to transformation reactions such as the oxidative decomposition of catechins, the hydrolysis of terpene alcohols, the hydrolysis of glycosidic aroma precursors, lipid oxidation, oxidative degradation of carotenoids, and oxidative deamination of amino acids. This study helps to enrich the understanding of the aroma formation of tea and provides technical references for enhancing the aroma of tea products.

In order to study the effects of lychee wood chips with different toasting degrees used in the aging process on the flavor of lychee brandy, the quality and volatile flavor components of lychee brandy aged with lightly toasted (LT), moderately toasted (MT) or heavily toasted (HT) lychee wood chips were evaluated and analyzed using sensory evaluation, electronic nose and gas chromatography-mass spectrometry. Raw and aged lychee brandy with heavily toasted oak chips were used as controls. The results of electronic nose analysis were in good agreement with those of sensory evaluation, and the brandy aged with heavily roasted lychee wood chip wood had the highest overall sensory score. A total of 44 volatile aroma compounds were identified in the five brandy samples, and the types and contents of volatile components varied greatly among these samples, each with their unique olefinic flavor substances. The major volatile components of aged lychee brandy were alcohols, esters, olefins, along with lesser amounts of aldehydes and ketones, alkanes, and aromatic hydrocarbons. Ethyl decanoate, ethyl acetate, ethyl caprylate, 2-methylbutanol, isoamyl alcohol, isobutanol, alpha stigmasterol and beta stigmasterol together constituted the major flavor profile of the aged lychee brandy. Therefore, aging with a moderate amount of heavily roasted lychee wood chips resulted in better improvement in the quality of lychee brandy compared to heavily toasted oak chips.

Fermented kidney bean milk made from germinated kidney bean was prepared with six strains of lactic acid bacteria producing γ-aminobutyric acid (GABA) at high yield separately. Sensory evaluation, gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O) coupled with odor activity value (OAV) analysis were employed to explore the effect of different lactic acid bacteria on the flavor of fermented kidney bean milk. The results showed that a total of 17 volatile flavor compounds were identified in the six fermented kidney bean milk samples, among which, hexanol, benzaldehyde, eugenol, 4-vinyl-2-methoxyphenol, 2-ethylhexyl salicylate, and benzoic acid were identified as key aroma compounds. The sensory evaluation results indicated that lactic acid bacteria fermentation could enhance the sour, fermented, beany, and sweet aromas of fermented kidney bean milk, while significantly reducing the beany odor. Among the six strains, kidney bean milk fermented with Pediococcus pentosaceus Z-6-2 possessed the highest GABA content (225.50 mg/L) and the best flavor, offering significant potential for further development. This study provides valuable strain resources for the development of fermented kidney bean milk beverage with lactic acid bacteria.

Myofibrillar protein (MP) and sarcoplasmic protein (SP) were extracted from pale, soft and exudative (PSE)-like chicken. The research investigated the differences in the heat-induced gel properties of SP-MP blends at 1:9, 2:8 and 3:7 ratios (m/m) and pure MP in order to select the appropriate SP/MP ratio. Furthermore, the differences in the gel properties, water distribution, intermolecular forces, gel electrophoresis pattern and microstructure of composite gels of SP treated with different ultrasonic powers (0, 300 and 600 W) at 20 kHz and MP were studied. The results showed that compared with the pure MP gel, the gel strength and water retention of the composite gel increased first and then decreased with the increase in SP addition, reaching the highest level at an SP/MP ratio of 2:8. After ultrasonic treatment at 600 W, the gel strength and water retention of the 2:8 composite gel were elevated by 113% and 47%, respectively, compared with those of the control group. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis showed that SP had a certain promotion effect on the aggregation and cross-linking of myosin, but this effect became weaker when the ratio of SP to MP was 3:7. Both hydrophobic interactions and disulfide bond content reached their highest levels and the composite gel formed a denser network structure when the ratio of SP to MP was 2:8, and the ultrasonic power was 600 W. In conclusion, the effect of addition of ultrasonic-treated SP on the gel-forming capacity of PSE-like chicken MP was related to its concentration, and ultrasonic-treated SP favored the formation of MP gel structure, which effectively improved the gel characteristics of PSE-like chicken MP.

In order to investigate the synergistic effect of extrusion and polyphenol treatment on the physicochemical and structural characteristics of corn starch (CS), four polyphenols (ferulic acid, gallic acid, quercetin and curcumin) were selected in this study. The solubility, swelling power, pasting properties, thermal characteristics, antioxidant capacity, in vitro digestibility and crystal structure of the extruded CS with polyphenols were evaluated. The results showed that extrusion combined with polyphenol treatment resulted in an increase in the solubility, swelling power and pasting temperature of CS, and a decrease in the gelatinization enthalpy, peak viscosity and setback value, as well as a significant improvement in the scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation and anti-digestive properties. The binding of polyphenols to CS was dominated by hydrogen bonding during the extrusion process, leading to a decrease in the short-range orderliness of CS and eventually the formation of a special V-shaped crystal structure. After the combined treatment, the structure of CS became denser as observed by scanning electron microscope (SEM). This study provides theoretical guidance for the application of polyphenols in extruded starch-based functional foods.

To improve the drying efficiency and quality of hot air-dried apple slices with blanching pretreatment, this study systematically evaluated the effects of two blanching pretreatments, hot water blanching and vacuum steam pulsed blanching, on the macroscopic drying performance of apple slices. The results indicated that under the conditions of 0.07 MPa vacuum, two blanching cycles, and blanching time of 3 minutes, vacuum steam pulsed blanching significantly enhanced the rehydration rate and textural quality of apple slices while reducing the drying time. Paraffin sectioning, microscopic observation and image processing were used to compare the microstructural changes of apple slices in terms of cell cross-sectional area, perimeter, equivalent diameter, cell roundness, wall roughness factor, and porosity under different branching conditions (temperature and time for hot water blanching; vacuum level, number of cycles, and time for vacuum steam pulsed blanching). The results showed that with the increase in temperature, blanching time and number of blanching cycles, apple cells exhibited changes that accelerated water evaporation during subsequent drying, thus shortening the drying time. Additionally, the relationship between microstructural parameters and rehydration ratio was fitted to a polynomial regression model. The findings of this study provide a theoretical basis for understanding the mechanisms by which vacuum steam pulsed blanching affects the microstructure and quality of dried apple slices.

In order to explore the effect of protein/nucleic acid deglycase DJ-1 (DJ-1) expression on the meat quality of Qinchuan cattle during postmortem aging, the longissimus dorsi muscle of Qinchuan cattle slaughtered at 25 months of age was aged at 4 ℃ postmortem and evaluated for meat quality, DJ-1 expression and relative levels of reaction oxygen species (ROS) after 0, 2, 4, 6 and 8 days. The correlation between DJ-1 expression and meat quality indexes and ROS was analyzed. Four-dimensional label-free quantitative (4D-LFQ) proteomics was deployed to analyze DJ-1 and the related differential proteins. The results showed that with the increase in aging time, the pH decreased first and then increased, the L*, a*, shear force, centrifugal loss and drip loss increased first and then decreased, and the b*, ROS and DJ-1 expression continued to increase. DJ-1 expression was significantly positively correlated with centrifugal loss, L*, b* and ROS (P < 0.01) and significantly negatively correlated with pH (P < 0.01) as well as shear force (P < 0.05), but was not significantly correlated with a* or drip loss (P > 0.05), leading us to conclude that changes in DJ-1 expression during postmortem aging is closely related to beef tenderness. 4D-LFQ proteomics revealed that DJ-1 and its functionally related differential proteins promoted structural changes of beef muscle during postmortem aging by forming a homodimer, binding to kinases, ion channels and ubiquitin proteases, and regulating the apoptosis signaling pathway through proteasomal protein decomposition, glycolysis and the regulation of oxidative stress response. At the same time, they caused changes in the intracellular environment through complex biochemical reactions, which in turn affected beef quality attributes of Qinchuan cattle such as tenderness.

To investigate the metabolic characteristics of salmon muscle consumed raw under fluctuating temperature chilled conditions, differential metabolites in salmon samples stored for different periods (0, 4 and 9 days) at 4 or 10 ℃ were analyzed by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS)-based metabolomics combined with multivariate statistical analysis. Results showed that the composition of metabolites was significantly different between fresh and stored salmon at each temperature (P < 0.05), and the difference was more obvious in samples stored at 10 ℃. By orthogonal partial least squares-discriminant analysis (OPLS-DA), 47 and 62 differential metabolites were identified between fresh salmon and samples stored at 4 and 10 ℃, respectively, including lipids and lipid-like compounds, amino acids and their derivatives, organic acids and their derivatives, nucleotides and their derivatives. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis and metabolic path mapping showed that the biosynthesis of amino acids was the important metabolic pathway for salmon samples stored at 4 ℃. L-histidine and L-tryptophan were involved in more metabolic pathways and, therefore, could be used as metabolic markers for raw salmon stored at 4 ℃. Additionally, the energy metabolism pathway was the major metabolic pathway for salmon samples stored at 10 ℃, and L-histidine, pyruvate, linolenic acid and purine metabolites played important roles and thus could be used as metabolic markers for raw salmon stored at 10 ℃.

In this study, the inhibitory effect of an edible composite composed of coating water-soluble chitosan and curdlan on postharvest infection of cherry tomatoes by Botrytis cinerea and the underlying mechanism was investigated. The mycelial growth, minimum inhibitory concentration (MIC), spore germination and membrane permeability of B. cinerea were studied. The results showed that the composite coating had a significant inhibitory effect on the growth of B. cinerea. After treatment with the composite coating, the cell membrane was damaged, resulting in leakage of intracellular contents and hyphal shrinkage. Meanwhile, it significantly inhibited the expansion of B. cinerea lesions. The composite coating might inhibit B. cinerea mainly by affecting the cell wall and membrane. These results suggest that the water-soluble chitosan/curdlan edible composite coating can be used as an effective antimicrobial material in the storage and preservation of cherry tomatoes.

In this study, the effects of volatile substances from Trichoderma erinaceum M6-5 on the cell membrane and wall of Alternaria alternata were investigated. To evaluate the antifungal effect, the culture medium inoculated with T. erinaceum and cultured for 5 days was covered with the culture medium containing A. alternata and cultured at 30 ℃ for 3, 5 and 7 days. The mycelia of A. alternata in the treatment and control groups were observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and were collected to observe the integrity of the cell membrane by propidiumiodide (PI) staining, and cell membrane-related indexes such as electrical conductivity were measured. The morphological changes of apical growth cells were detected by calcofluor white (CFW) staining, and alkaline phosphatase (AKP) activity and N-acetylglucosamine concentration were determined. The results showed that during the culture period, the volatile substances produced by T. erinaceum had good antifungal effects on A. alternata. SEM and TEM images showed that the mycelia of A. alternata appeared shriveled, swollen and broken partially after the treatment. A greater reduction in cytoplasmic matrix was noted when compared with the control group, which was accompanied by local plasmolysis. For the control group, the mycelium growth was normal, the spore structure was complete, the cross-section structure was clear, the cytoplasm was uniform, and the cell wall and membrane structures were normal. After the treatment, the electrical conductivity, malondialdehyde (MDA) level, protein and nucleic acid leakage significantly increased relative to the control group. PI staining showed that the mycelia of the treated group emitted red fluorescence, indicating that the volatile substances of T. erinaceum damaged the integrity of the cell membrane, thus resulting in the leakage of cellular contents and marked disruption of the normal function of the cell membrane. CFW staining showed no significant differences between the treated and control groups with respect to the fluorescence intensity of mycelia, AKP activity or n-acetylglucosamine concentration indicating that the volatile substances of T. erinaceum did not damage the cell wall of A.alternata, and their major targets were not the cell wall. In conclusion, the antifungal target of volatile substances from T. erinaceum M6-5 is the cell membrane of A. alternata.

This study investigated the combined application of visible/near-infrared (Vis-NIR) spectroscopy with linear discriminant analysis (LDA) and machine learning (ML) for the classification of apples with different degrees of damage. The Vis-NIR spectral data of apples with different degrees of damage were collected, and the effect of different spectral preprocessing methods on the support vector machine (SVM) classification model was analyzed. LDA was used to reduce the dimensionality of the preprocessed spectral data, and five machine learning models including SVM, random forest (RF), K-nearest neighbor (KNN), decision tree (DT) and extreme gradient boosting (XGBoost) were constructed and compared for the classification of apple damage. The results showed that the SVM model based on preprocessed spectra with Savitzky-Golay (SG) smoothing had the best classification performance, with an accuracy of 87.3%. After dimensionality reduction using LDA, the classification accuracy of all the models was significantly improved, with the highest increase of 16% being observed in the DT model. The KNN model showed the best classification performance, with an accuracy of 96.0% and a precision of 96.4%. This study provides a basis for efficient and accurate assessment of the degree of mechanical damage in apples.

In this study, hyperspectral technology was used to solve the problem of identifying the geographical origin of spearmint. First, 375 spearmint leaf samples from 5 geographical origins were selected for hyperspectral data collection, and the hyperspectral data were preprocessed by multiplicative scatter correction (MSC) and analyzed by principal component analysis (PCA); the principal component variables were used to construct Wilks Λ statistics, which were then ranked in an increasing order. Then, the weight coefficient curves of the principal components corresponding to the first three smallest Wilks Λ values were drawn at each wavelength; a total of 37 feature wavelengths were obtained, namely the peak and valley wavelengths in the coefficient curves. Next, Fisher discriminant analysis (FDA) was used to construct the input variables for a model for graphical origin identification of spearmint. At last, a support vector machine (SVM) model and a back propagation neural network (BPNN) model for identifying the geographical origin of spearmint were constructed. The results indicated that the SVM model outperformed the BPNN model, with discrimination accuracy of 99.67% and 98.67% in the training and test sets, respectively. Therefore, the SVM model, constructed using PCA combined with Wilks Λ statistics, can effectively identify the geographical origin of spearmint. In this model, the extracted feature wavelengths are not affected by the number of physicochemical indexes, making the model robustness.

With the acceleration of industrialization, heavy metal pollution has become increasingly severe, posing a significant threat to human health. In recent years, various biosensors have been widely used for heavy metal detection. Among them, electrochemiluminescence (ECL) sensors have garnered attention due to their high sensitivity, rapid response, and real-time detection capability. Noble-metal nanocomposite materials play an important role in enhancing sensor performance due to their unique physicochemical properties. This paper summarizes the latest research progress on ECL sensors based on noble-metal nanocomposite materials in heavy metal detection. It emphasizes the role of the nanocomposite materials in improving sensor sensitivity and discusses their performance in heavy metal detection, as well as the design principles and specificity of ECL sensors. Furthermore, it discusses future prospects for improving sensor performance and optimizing the application of microfluidic platforms through technological advancements. We hope that this review will provide more effective solutions for challenges in food safety testing.

Okara, the major by-product from the production of soybean products, is rich in dietary fiber, protein, fat, vitamins and other nutrients, and functions to regulate the intestinal flora, prevent diabetes, control body mass, prevent and treat cardiovascular diseases. However, there are many problems with okara: high-water content, poor taste and susceptibility to spoilage, restricting its high-value development. Microbial fermentation is a green and safe treatment for okara, which can improve the functional properties and taste and prolong the shelf life, thereby increasing the utilization value. Although the effect of fermentation on the functional properties of okara has been extensively studied, it has not been systematically elaborated and summarized. Therefore, this article focuses on the hotspots in okara fermentation research by means of bibliometrics and visualization analysis. Based on the obtained results, it provides a systematic review on the biotransformation of okara by microbial fermentation, the metabolism pattern of okara nutrient components, the fermentation methods of okara and its application scenarios in foods, aiming at providing a theoretical basis for the value-added utilization and functional development of okara in plant-based foods.

As the dominant spoilage bacterium in meat, Pseudomonas poses a significant threat to meat quality and safety. The biofilm of Pseudomonas not only enhances stress resistance but also provides bio-protection, thereby making the decontamination of Pseudomonas more challenging. In recent years, many studies have been conducted on the mechanism of Pseudomonas biofilm formation, with particular emphasis on the regulatory effect of quorum sensing (QS) and cyclic di-guanosine monophosphate (c-di-GMP) on the mechanism of Pseudomonas biofilm formation. There may be a complex interaction between QS and c-di-GMP. In addition, compared with traditional biofilm inhibition strategies, the development of new inhibition strategies based on the QS system, c-di-GMP and their relationship, which can be more targeted, has more practical significance. Therefore, this article describes the synthesis process of the QS system and c-di-GMP signal molecules and reviews the mechanism of Pseudomonas biofilm formation from the perspectives of the QS system, c-di-GMP and their relationship. Besides, it summarizes the inhibition strategies targeting the QS system and c-di-GMP. This review aims to provide a theoretical foundation for effectively controlling Pseudomonas biofilm in the food industry.

Phages are the most diverse and abundant biological entities on earth. In recent years, the proliferation of high-throughput sequencing technology has led to a surge in research on the composition and functions of phages in diverse ecological niches. Particularly, phages in fermented foods have been receiving increasing attention from researchers, which interact with their bacterial hosts through the lytic and lysogenic life cycles, playing important ecological roles and influencing the succession of microbial communities. Additionally, phages also exhibit potential auxiliary metabolic functions, which in turn affects the formation of flavor substances in fermented foods to a certain extent. This paper provides a comprehensive review of the present status and hot topics of research on phages in fermented foods, with a specific focus on the composition, diversity, genomic DNA extraction techniques and auxiliary metabolic functions of phages as well as their interactions with the host and the underlying mechanism (e.g., clustered regularly interspaced short palindromic repeats (CRISPR) and binding receptors). Finally, this review concludes with a discussion of future research directions, aiming to provide a reference for further research and application of phages in fermented foods.

In foods, there are many types and sources of harmful substances that can accumulate in the human body, thereby posing a threat to human health. Therefore, it is crucial to develop efficient, rapid and portable visual detection devices with low detection limits. In recent years, nanozymes, nanomaterials with natural enzyme-like activity, have played an important role in the construction of colorimetric sensors due to their tunable enzyme activity and high stability, enabling efficient and rapid visual detection of harmful substances in foods. Redox-type nanozymes are the most researched nanozymes. Therefore, this paper introduces the types of redox-type nanozymes and elucidates their catalytic mechanisms. It focuses on reviewing the application of redox-type nanozymes in constructing colorimetric sensors for detecting common representative harmful substances (heavy metals, pesticide residues, and mycotoxins) in foods. Finally, we summarize the advantages and disadvantages of colorimetric assays based on redox-type nanozymes in the field of food safety detection, and propose some solutions to the problems in order to provide a reference for future research.

Fermented meat products are a typical representative of traditional meat products, which are highly appreciated by consumers for their unique flavor, texture, and nutritional value. Traditional fermented meat products are often produced by natural fermentation, and different fermentation environments lead to variability in the flavor of fermented meat products. Microorganisms, especially common ones such as lactic acid bacteria, staphylococci, yeasts and molds, play a crucial role in the flavor formation of fermented meat products. Microorganisms in fermented meat products can promote the formation of flavor compounds through protein hydrolysis, amino acid and lipid metabolism, fatty acid metabolism, and carbohydrate metabolism. Herein, we review the types and formation mechanism of volatile flavor compounds in fermented meat products, focusing on the metabolic pathways of the major microorganisms (lactic acid bacteria, staphylococci, yeasts and molds) affecting the flavor formation of fermented meat products. Through this review, we hope to provide a theoretical basis for regulating the flavor properties of fermented meat products.

The soymilk powder market has a broad development prospect in China, and its industry is burgeoning. Soymilk powder has become a daily food for most people, but the allergenicity of soymilk powder is always a bottleneck for the industry. Soybean and cow milk, as raw materials for producing soymilk powder, are among the major food allergens, which limit the wide application of soymilk powder. Therefore, this paper reviews the structural properties and mechanism of action of allergenic proteins in soymilk powder as well as the techniques to detect their allergenicity, and describes the methods to reduce the allergenicity of soymilk powder. Meanwhile, it discusses recent developments and future prospects in the hypoallergenic soymilk powder industry in China. Hopefully, this review will provide a reference for new product development, quality and safety control, establishment and standardization of standards for hypoallergenic soymilk powder in China.

High-moisture extrusion is a technology to prepare textured plant protein by high temperature, high pressure and high shear force. With its environmentally friendly, health and nutritional advantages, high-moisture extrusion has become the major technique to produce plant protein-based meat analogues. However, there is still a gap with meat in texture, taste and color, so improving the quality of high-moisture extruded plant protein-based meat analogues has become the focus of attention from researchers and producers. Polysaccharides are often used as texture modifiers in high-moisture extrusion processing. This paper focuses on the effects of several polysaccharides such as starch, gum and dietary fiber on the quality and structure of high-moisture extruded plant protein-based meat analogues, and summarizes the interaction mechanism between polysaccharides and proteins during the extrusion process. This review aims to tap the application potential of polysaccharides in the production of high-moisture extruded plant protein-based meat analogues in order to develop more plant protein-based meat analogues with improved quality using polysaccharides and to achieve improvement in the nutrition and quality of plant protein-based meat analogues.

Foodborne pathogenic microorganisms are a serious threat to food safety. Currently, traditional biochemical assays are facing a series of challenges in the detection of foodborne pathogens. In recent years, with the gradual development of CRISPR (clustered regularly interspaced short palindromic repeats) technology, the CRISPR/CRISPR-associated proteins (Cas) system with trans-cleavage activity has received much attention from researchers. In this article, the origin, classification and principles of CRISPR/Cas systems with trans-cleavage activity are summarized. This paper also reviews the versatile application of trans-cleavage CRISPR/Cas systems in the field of foodborne pathogens, and concludes with a discussion of the advantages, disadvantages and future directions of this technology.

Carbon dots (CDs) are a new type of carbon-based nanomaterials with excellent fluorescence properties, low toxicity, which offer an abundant source of carbon precursors. An aptamer (Apt) can specifically bind to its target molecule, and its application in sensors can dramatically improve the detection accuracy and sensitivity. Fluorescent biosensors with CDs as the signal transduction element and Apt as the target recognition element have attracted attention from researchers. In this paper, we review the structure, classification, fluorescence properties of CDs and the advantages of Apt, with a focus on the strategies for constructing fluorescent Apt sensors based on CDs and the current status and recent progress in their application in food safety detection, aiming to provide a reference for research in the fields of food quality supervision and on-site rapid detection technology for food safety.