The aim of this study was to assess the effect of nitric oxide (NO)-mediated mitochondrial apoptosis on Tan sheep meat tenderness during postmortem aging. The hind leg muscle of Tan sheep was injected with 0.8% NaCl (control), 20 mmol/L aminoguanidine hydrochloride (AH) or 90 mmol/L L-arginine (L-Arg) and aged at 4 ℃ for 0, 6, 12, 24, 48, 96, and 192 h. NO and inducible nitric oxide synthase (iNOS) contents, cytochrome c (Cyt c) redox state, oxidative stress level, mitochondrial apoptotic pathways, and tenderness were measured during postmortem aging. The results indicated that at 12 and 24 h after slaughter, NO and iNOS levels were significantly higher, and ATP levels were significantly lower in the L-Arg group than in the control group (P < 0.05). At 24 and 48 h, Cyt c reduction levels and superoxide dismutase (SOD) activity were significantly higher, while the level of reactive oxygen species (ROS) was significantly lower in the AH group than in the control group (P < 0.05). From 12 to 96 h, ATP contents were significantly lower in the L-Arg group than in the control group (P < 0.05). In addition, at 24 h, Ca2+ concentration significantly increased in the L-Arg group compared with the control group (P < 0.05). At all time points except 24 h, the caspase-3 activity in the L-Arg group was significantly higher than that in the control group (P < 0.05). Moreover, it was found that the Bax/Bcl-2 ratio, pH, and myofibril fragmentation index (MFI) in the L-Arg group were significantly higher than those in the control group at all time points after slaughter (P < 0.05). Shear force was significantly lower in the L-Arg group but significantly higher in the AH group than in the control group (P < 0.05). In conclusion, NO exacerbates mitochondrial oxidative stress and directly upregulates ROS levels during the postmortem aging of Tan sheep meat, leading to a decrease in SOD activity, irreversible opening of mitochondrial permeability transition pore (MPTP), and ultimately mitochondrial damage. In addition, by controlling the redox state of Cyt c, NO indirectly activates caspase-3 activity to accelerate apoptotic energy metabolism, deplete ATP and consequently maintain myocyte homeostasis. Furthermore, NO affects the release of Ca2+, up-regulates the Bax/Bcl-2 ratio, and induces the occurrence of mitochondrial apoptotic cascade, ultimately resulting in an increase in MFI and a decrease in shear force and, consequently, improving the tenderness of Tan sheep meat.

In this study, ZnO nanoparticles with high crystallinity and good dispersibility for efficient and green photocatalytic degradation of T-2 toxin were successfully prepared by a green and mild solvent hydrothermal method. The properties and T-2 toxin degrading performance of the nanoparticles were characterized by high-resolution transmission electron microscopy (HRTEM) and transient photocurrent response (TPR), and the factors affecting the T-2 toxin degrading performance and the underlying mechanism were explored. The results showed that the average particle size of the prepared nanoparticles was 43.23 nm. Under optimized conditions, more than 95% of T-2 toxin at an initial concentration of 5 μg/mL was removed after photocatalytic degradation with the nanoparticles for 240 min, with a degradation kinetic constant of 0.029 9 μg/(mL·min). The optimal catalyst dose was 0.5 mg/mL, and the optimal pH was 5–9 for the degradation of T-2 toxin. The photoelectric characterization confirmed the excellent optical absorption, response and charge separation performance of the ZnO nanoparticles and identified hydroxyl radicals to play a dominant role in T-2 toxin degradation. The current work provides an effective theoretical basis and technical support for the green and efficient degradation, conversion and removal of T-2 toxin.

In order to explore the differences in the quality indexes of different rice varieties, this study used principal component analysis (PCA) and membership function analysis (MFA) for comprehensive evaluation of 13 quality indexes of 46 high-quality japonica rice varieties in southern regions of Northeast China, and classified the rice varieties by cluster analysis (CA). The results showed that there were significant differences in all quality indexes among different rice varieties. Among the quality indexes, the coefficient of variation for grain chalkiness rate was the largest (66.32%), while that for amylose content was the smallest (3.28%). Correlation analysis showed that there were different degrees of correlation among the 13 quality indexes. Through PCA, four principal components (PCs) were determined to comprehensively evaluate the quality of different rice varieties. PC1 was synthesized from appearance, hardness, viscosity, balance degree and taste score, PC2 from the percentage of brown rice, milled rice and whole milled rice, PC3 from grain chalkiness rate and chalkiness degree, and PC4 from length-to-width ratio, amylose content and protein content. The quality of the 46 rice varieties was evaluated and ranked by MFA. The top 10 varieties were Liaogeng 1925, Yangeng 935, Tiegengxiang 3, Shennong 625, Liaogeng 1499, Liaogengxiang 1, Yangeng 241, Liaogeng 419, Tiegeng 11 and Yangeng 313. The 46 varieties were classified into five categories by CA. Class I included one variety (2.17%), whose quality was the best. Class II included 18 varieties (39.13%), and their rice quality was excellent. Class III included 18 varieties (39.13%), and their rice quality was moderate. Class IV included 7 varieties, and their rice quality was poor. Class V included two varieties (4.35%), and their rice quality was the worst. This conclusion can provide an important reference for screening high quality rice varieties.

In this study, the hazards and thermal reaction products were monitored in roasted fish marinated with spices. Correlation analysis and dimensionality reduction analysis were carried out using multivariate statistical analysis methods to explore the effect and mechanism of spices on the generation of multiple hazards in roasted fish, aiming to improve the safety of roasted fish through marinating with spices. The results indicated that six spices, including thyme, prickly ash, red pepper, bay leaf, dried ginger, and black pepper, had a certain inhibitory effect on hazards in roasted fish. The highest inhibitory rates of heterocyclic amines (HAAs), acrylamide (ACY), 5-hydroxymethylfurfural (5-HMF), and polycyclic aromatic hydrocarbons (PAHs) were 65.51%, 61.71%, 35.02%, and 35.10%, respectively. Collectively, black pepper and red pepper had better inhibitory effects. Through non-targeted omics analysis of the thermal reaction products in roasted fish, it was found that various hazards in roasted fish were positively correlated with heterocyclic compounds but negatively correlated with organic acids and their derivatives. It was speculated that spices could reduce the formation of hazards by reducing heterocyclic compounds and increasing organic acids and their derivatives in roasted fish.

Fe3O4 magnetic molecularly imprinted polymers (Fe3O4@MIPs) were prepared by adopting surface molecular imprinting technology using Fe3O4 particles as the magnetic core, resveratrol as the template molecule, and dopamine (DA) as the functional monomer and crosslinking agent. The surface groups, particle shape, skeleton structure, and magnetization intensity of Fe3O4@MIPs were characterized through scanning electron microscopy (SEM), infrared (IR) spectroscopy, X-ray diffraction (XRD) and vibrating sample magnetometry (VSM), and its adsorption performance for resveratrol was detected using high performance liquid chromatography (HPLC). The results indicated that Fe3O4@MIPs had high magnetization intensity and showed a stable morphology. When the adsorption time was 150 minutes and the concentration of resveratrol was 40 μg/mL, the maximum adsorption capacity of 35.101 μg/mg was obtained, indicating a good adsorption performance. In conclusion, solid phase extraction with Fe3O4@MIPs as the sorbent enabled selective recognition and enrichment of resveratrol from pomegranate rind.

In this study, surface imprinting technology was used for the one-step preparation of a core-shell magnetic molecularly imprinted polymer (Fe3O4-NH2@MIP) with amino functionalized magnetic iron trioxide (Fe3O4-NH2) as the magnetic core at a mass ratio of juglone to functional monomer to cross-linking agent of 1:8:40. The structure, morphology and magnetic strength of the material were characterized by multiple techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR). The adsorption performance was studied through dynamic adsorption and isothermal adsorption experiments. Results showed that an imprinted layer with a thickness of about 75 nm was successfully polymerized on the surface of Fe3O4-NH2, with a nearly spherical shape and a regular crystal structure and a saturation magnetic strength of 48.50 emu/g. The layer could be quickly separated in five seconds. When the adsorption time was 100 minutes and the concentration of juglone was 100 μg/mL, good adsorption performance was obtained with an adsorption capacity of 32.89 μg/mg, the kinetic adsorption process was closer to a pseudo-second-order model, and the adsorption data accorded with the Langmuir isotherm, indicating that Fe3O4-NH2@MIP enables efficient separation and enrichment of juglone from walnut green peel extract. This study is of reference significance for the development of more biological activity of juglone and the expansion of its application in food, pharmaceutical and other industries.

Herein, multicomponent oleogels composed of octacosanol and behenic acid were constructed and characterized, and the assembly mechanism of the composite system was preliminarily analyzed. The results showed that the crystal microstructure, rheological properties, thermal properties and oil-holding capacity of the composite system significantly varied with the mass ratio of octacosanol to behenic acid. When the mass ratio of octacosanol to behenic acid was 8:2, the system showed synergistic effect, the crystal morphology was fibrous, and the crystal was distributed in a mixture of α and β’ polymorphs, with the highest elasticity modulus and the strongest oil holding capacity being observed. When the mass ratio of octacosanol to behenic acid was 4:6, there was an antagonistic effect in the system, the crystal morphology showed spherical fibrous aggregates, and the crystal forms were dominated by the α polymorph, the lowest crystallization temperature/melting temperature and the weakest gel strength and oil-holding capacity being observed. These results lay a theoretical foundation for promoting the application and production of oleogels in functional foods, and provide novel technical ideas for improving the utilization of octacosanol.

In this study, circular dichroism (CD) and molecular dynamics (MD) simulation were used to investigate the thermal unfolding pathway of staphylococcal enterotoxin B (SEB) at temperatures of 298–371 and 298–500 K, and the relationship between the experimental and simulation results were explored. Our computational findings on the secondary structure of SEB showed that at room temperature, the CD spectroscopic results were highly consistent with the MD results. Moreover, under heating conditions, the changing trends of helix, sheet and random coil obtained by CD spectral fitting were highly consistent with those obtained by MD. In order to gain a deeper understanding of the thermal stability mechanism of SEB, the MD trajectories were analyzed in terms of root mean square deviation (RMSD), secondary structure assignment (SSA), radius of gyration (Rg), free energy surfaces (FES), solvent-accessible surface area (SASA), hydrogen bonds and salt bridges. The results showed that at low heating temperature, domain I without loops (omitting the mobile loop region) mainly relied on hydrophobic interaction to maintain its thermal stability, whereas the thermal stability of domain II was mainly controlled by salt bridges and hydrogen bonds. Under high heating temperature conditions, the hydrophobic interactions in domain I without loops were destroyed and the secondary structure was almost completely lost, while domain II could still rely on salt bridges as molecular staples to barely maintain the stability of the secondary structure. These results help us to understand the thermodynamic and kinetic mechanisms that maintain the thermal stability of SEB at the molecular level, and provide a direction for establishing safer and more effective food sterilization processes.

In order to improve the activity and thermal stability of phytase and to enhance its application potential in the food processing industry, single-site mutants were constructed by homology modeling of phytase YiAPPA and directed mutagenesis of lysine (Lys) and glycine (Gly) residues located on the molecular surface. The mutant K216R with significantly improved activity and thermostability and the mutant K189R with improved thermostability were obtained. Subsequently, the combined mutant K189R/K216R was constructed and its enzyme activity and thermal stability were characterized. Compared with YiAPPA, the half-life of K189R/K216R at 80 ℃ was increased from 14.81 to 23.35 min, the half-inactivation temperature (T5030) from 55.12 to 62.44 ℃, the melting temperature (Tm) from 48.36 to 53.18 ℃, and the specific enzymatic activity of K189R/K216R at 37 ℃ and pH 4.5 from 3 959.98 to 4 469.13 U/mg. Molecular structure modeling analysis and molecular dynamics simulation revealed that the introduction of new hydrogen bonds into K189R/K216R could improve the stability of some structural units of the enzyme, thereby enhancing its thermostability. The improvement in its activity was mainly attributed to the increase in the volume of the catalytic pocket of K189R/K216R. In conclusion, the present study demonstrated that the strategy of amino acid residue mutation on the protein surface effectively improves the activity and thermostability of phytase YiAPPA. Our findings can serve as a reference for molecular modification of phytase and other enzymes.

In this study, buffalo cheese was prepared with rennet from Moringa oleifera seeds. The process was optimized based on sensory characteristics and hydrolysis degree. The composition of water-soluble peptides from the cheese was analyzed. Furthermore, bioactive peptides with angiotensin converting enzyme (ACE) inhibitory activity were identified and their potential molecular mechanisms of action were explored. The optimal conditions determined were as follows: pH 5.56, rennet dose 0.14%, incubation time 32 min, and stretching temperature 80 ℃. Under these conditions, the hydrolysis degree of cheese was 12.56% with a uniform and elastic texture, a soft and delicate taste, a uniform and glossy color, and a rich aroma. By liquid chromatography-tandem mass spectrometry (LC-MS/MS), 1 600 peptides with molecular mass less than 3 kDa were detected in the cheese, 613 of which demonstrated good bioactivity, predominately derived from β-casein and αS1-casein. Notably, 37.29% of the peptides exhibited ACE inhibitory activity. By comparing with the bioactive peptide database and using bioinformatics, four peptides proven to have ACE inhibitory activity and four novel peptides with potential ACE inhibitory activity were identified. Molecular docking showed that the four novel peptides could effectively bind to ACE. Among them, FGGL and FSPL bound tightly to the S2 active pocket, thus exhibiting strong ACE inhibitory activity. This study provides a scientific basis for the development and utilization of new plant rennet resources and characteristic buffalo cheese.

In this study, the de novo synthesis pathway of 2’-FL was established in Escherichia coli BL21star(DE3). The β-galactosidase gene (lacZ) and the UDP-glucose lipid carrier transferase gene (wcaJ) were knocked out by the CRISPR/Cas9 system. The effects of various exogenous α-1,2-fucosyltransferases on 2’-FL synthesis were investigated. Subsequently, the transcriptional levels of genes involved in the synthesis pathway were regulated, and the fermentation conditions were optimized. The results showed that after fermentation for 72 h, a 2’-FL concentration of 0.34 g/L was obtained in shake flasks with overexpression of the de novo synthesis pathway genes in E. coli BL21star (DE3), and the concentration of 2’-FL was increased to 2.12 g/L by knockout of the lacZ and wcaJ genes. Expression of α-1,2-fucosyltransferase Wcfb from Bacteroides fragilis in shake flasks resulted in the highest concentration of 4.12 g/L. Under the optimized fermentation conditions: 28 ℃ and 0.2 mmol/L final isopropyl-β-D-thiogalactoside (IPTG), the 2’-FL concentration was increased to 5.01 and 31.2 g/L in a shake flask and in a 5 L fermenter under fed-batch condition, respectively.

The organic acids and microbial community structure of fermented grains in the dominant stacking fermentation rounds for sauce-flavor Baijiu production (i.e., the 2nd and 3rd rounds corresponding to the 3rd and 4th rounds of base liquor) were analyzed using high-performance liquid chromatography (HPLC) and high-throughput sequencing, and the interaction between them was investigated. The results revealed that lactic acid, acetic acid, and succinic acid were the primary organic acids present in fermented grains at mean values of 32.70, 4.87 and 1.93 mg/g, respectively. In total, 8 dominant bacterial genera and 7 dominant fungal genera (average relative abundance > 1%) were identified across the two fermentation rounds. The dominant bacterial genera were Virgibacillus, Kroppenstedtia and Bacillus. The dominant fungal genera were Monascus, Thermomyces and Thermoascus. Principal coordinate analysis (PCoA) revealed that there was a significant difference in the structure of bacteria community between the second and third rounds of stacking fermentation, while the difference in the structure of fungal community was not significant. Co-occurrence network analysis showed that the bacterial-fungal (55.60%), bacterial-bacterial (50.57%), and fungal-fungal (91.67%) networks were mainly positively correlated, and there were more unknown interactions between bacterial communities. Mantel test analysis showed a significantly positive correlation between acidity and bacterial community structure (P < 0.01), and succinic acid was highly correlated with both bacterial and fungal community succession (P < 0.01). Spearman’s correlation analysis revealed that the bacterial community had a more significant correlation with organic acids than the fungal community, while the fungal community showed a negative correlation with most organic acids. Nine organic acids citric acid were positively correlated with Oceanobacillus, Bacillus, and Sphingobacterium but negatively correlated with Thermoactinomyces. The results of this study can provide a theoretical basis for the production of high-quality sauce-flavor Baijiu.

Objective: To study the effect and mechanism of luteoloside on the differentiation and lipid metabolism of 3T3-L1 preadipocytes. Methods: The cytotoxicity of different concentrations of luteoloside on 3T3-L1 preadipocyte was detected using methyl thiazolyl tetrazolium (MTT) assay. Cell differentiation was induced by the cocktail method, and lipid droplets were observed by oil red O staining. The contents of triglyceride and total cholesterol in differentiated cells, as well as the secretion of related inflammatory factors such as tumor necrosis factor-α (TNF-α), interleukin (IL)-6, IL-10, leptin (LEP) and Adiponectin (ADPN) were measured. The relative expression levels of peroxisome proliferators activated receptor (PPAR) γ, CCAAT-enhancer-binding proteins (C/EBP)-α, sterol regulatory element-binding protein 1 (SREBP1), PPARα, uncoupling protein 1 (UCP-1), and carnitine palmitoyltransferase 1 (CPT-1) were analyzed by Western blotting. Results: The survival rate of 3T3-L1 preadipocytes decreased with the increase in luteoloside concentration, being above 80% at luteoloside concentrations of 5–60 μg/mL. Treatment with luteoloside significantly inhibited the differentiation of 3T3-L1 preadipocytes and reduced lipid accumulation. Luteoloside down-regulated the contents of TC and TG, the secretion of TNF-α, IL-6 and LEP, but up-regulated the secretion of IL-10 and ADPN. Luteoloside down-regulated the protein expression levels of PPARγ, C/EBP-α and SREBP1, but up-regulated those of PPARα, UCP-1 and CPT-1. Conclusion: Luteoloside can suppression the differentiation and lipid metabolism of 3T3-L1 preadipocytes. The mechanism may be that luteoloside down-regulates the protein expression of PPARγ, C/EBP-α, and SREBP1 to inhibit fat synthesis. Furthermore, it activates PPARα to upregulate downstream proteins and promote fat consumption. Luteoloside may also regulate the secretion of cytokines and promote cellular lipolysis, thus improving lipid metabolism imbalance.

This study was carried out in order to investigate the effects of goji berries fermented by Lactobacillus plantarum NXU0011 on serum metabolites in mice with ulcerative colitis (UC). A mouse model of UC was induced by oral administration of dextran sodium sulfate (DSS) in drinking water. Four groups of mice were set up: DSS-induced model, control (Con), medication with mesalazine (MS), and intervention with lyophilized powder of L. plantarum NXU0011-fermented L. barbarum L. (LP + Ly). Non-targeted metabolomics was used to analyze differential serum metabolites among the four groups. In the positive ion mode, a total of 381 differential metabolites were identified, including 56 differential metabolites between the MS and DSS groups and 87 differential metabolites between the LP + Ly and DSS groups. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis of the significantly differential metabolites between the Con, LP + Ly and DSS groups revealed two metabolic pathways with the higher enrichment rates, arginine biosynthesis and vitamin digestion and absorption. This study provides a reference for the application of Lactobacillus-fermented goji berries to ameliorate UC.

In this study, in order to investigate the phospholipid composition characteristics and hypoglycemic activity of krill oil, we determined the content of total phospholipids in krill oil by a colorimetric method, examined the phospholipid composition by high-resolution mass spectrometry, and then applied the mass spectral fragmentation pattern and the databases Lipidmaps and Lipidblast for structural analysis. Furthermore, we evaluated the effect of krill oil on blood glucose, biochemical indexes and gene expression levels related to the regulation of blood glucose in a zebrafish model of hyperglycemia induced by the combined treatment of alloxan and sucrose, and explored the potential sites of hypoglycemic action of krill oil-specific phospholipid docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) by molecular docking. The results showed that the content of phospholipids in cold-extracted krill oil was 57.57%, and a total of 63 phospholipids were identified, of which phosphatidylcholine (PC) was the most abundant. Krill oil significantly reduced blood glucose concentration, elevated insulin and glycogen levels, inhibited the expression of FOXO1/PCK1/G6PC, and promoted the expression of GLUT4 in hyperglycemic zebrafish. Molecular docking revealed that DHA and EPA in krill oil might act at the FOXO1/PCK1/G6PC sites, suggesting close relationship between the phospholipid components and the hypoglycemic activity of krill oil. In summary, this study found that cold-extracted krill oil is rich in phospholipids and is a potential natural product with good hypoglycemic effect.

Roasted lamb chops were prepared by superheated steam roasting (SSR) and direct roasting (DR). To explore the formation mechanism of flavor substances, descriptive sensory analysis (DSA), an electronic nose (E-nose) system, head-space solid phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS), and gas chromatography-olfactometry (GC-O) were employed to analyze the sensory properties, fatty acid composition and volatile compounds of the SSR and DR samples. The DSA and E-nose results consistently revealed variations in aroma profiles between the two samples. The DR sample showed stronger roasted, fatty, and mutton-like aroma (P < 0.05). A total of 44 volatile compounds were identified from both samples. The contents of aldehydes, alcohols, and nitrogen-containing compounds in the DR sample were higher than those in the SSR sample. Totally 35 aroma-active compounds were identified by aroma extract dilution analysis (AEDA) combined with GC-O analysis, among which, decanal, hexanal, octanal, nonanal, (E,Z)-2,6-nonadienal, (E,E)-2,4-decadienal, (E,E)-2,4-nonadienal, 1-octen-3-one, 3-octen-2-one, 2-nonanone, heptanoic acid, 2-methylpyrazine, 3-(methylthio)propanal, benzothiazole, and 2-pentylfuran were the major ones. The types of aroma-active compounds in the two samples were similar, but their flavor dilution (FD) factors were different. Compared with the SSR sample, the content of total fatty acids in the DR sample significantly increased (P < 0.05). The content ratio of polyunsaturated fatty acids to saturated fatty acids (PUFA/SFA) in the DR sample was 40.66%, indicating higher nutritional value. Pearson’s correlation analysis showed that the oxidative degradation of unsaturated fatty acids such as oleic acid, linoleic acid, linolenic acid, and eicosenoic acid was closely related to the formation of the characteristic flavor in roasted lamb chops.

In this study, quantitative nuclear magnetic resonance (NMR) spectroscopy and high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) were used to analyze the differences in the composition of small-molecule nutrients in different parts (stems, leaves and flower buds) of ‘Dadi 95’ oilseed rape (Brassica napus L.) at the bud stage. The results showed that 53 small-molecule compounds were identified and quantified in total. Among these, substances with significant differences were leucine, isoleucine, valine, γ-aminobutyric acid, alanine, proline, phenylalanine, lactate, citrate, succinamide, β-D-glucose, α-D-glucose, sucrose, fructose, choline, betaine, fumaric acid, baicalein, ferulic acid, kaempferol, sinapine, trans-cinnamic acid, and hesperetin. Comparative analysis revealed that the content of carbohydrate was the highest in the stem of B. napus L., whereas choline, succinamide, most of amino acids, organic acids, and phenolic acids were mainly accumulated in the buds, and the dominant metabolites in the leaves were baicalein, sinapine, and citric acid. Metabolic pathway analysis demonstrated that these differential metabolites were mainly involved in the citrate cycle, flavone and flavanol biosynthesis, phenylalanine metabolism, aminoacyl-tRNA biosynthesis, valine, leucine and isoleucine biosynthesis, glycolysis/gluconeogenesis, and phenylalanine, tyrosine and tryptophan biosynthesis in the plant. The results from this study provide foundational data for comprehensively assessing the nutritional value of B. napus L. at the bud stage, and a scientific basis for selecting and breeding nutritious oilseed rape varieties.

To investigate the metabolite profiles of typical Chinese brick dark tea and the relationship between the metabolite types of brick dark tea and fungi isolated from it, this study used non-targeted metabolomics based on liquid chromatography-mass spectrometry (LC-MS) and feature-based molecular networking (FBMN) for metabolomic analysis of typical brick dark tea in China (Hubei Qingzhuan brick tea, Sichuan Kangzhuan brick tea, dark brick tea, Huazhuan brick tea and Fuzhuan brick tea from Hunan, and Fuzhuan brick tea from Shaanxi), fresh tea leaves and various fungal strains isolated from dark tea. The results indicated that the non-volatile metabolite profiles of brick dark tea tended to be classified into two groups according to production regions: one group included brick dark tea from Hunan and Shaanxi, and the other group included brick dark tea from Sichuan and Hubei. The major factor determining the metabolite profile was the stalk percentage of brick tea, and the stalk percentage of brick dark tea from Sichuan and Hubei was significantly higher than that of the other group. The major reason for the difference in metabolite profile between the two groups was the higher contents of flavan-3-ols as well as most amino acids and their derivatives in brick dark tea from Hunan and Shaanxi. The molecular network analysis of the metabolites of brick dark tea and fungi showed that linear and cyclic dipeptides derived from fungi were widely distributed in brick dark tea, especially Kangzhuan brick tea. Isopentenyl diketopiperazine compounds of diverse structural types were found to be abundant in Fuzhuan brick tea, which were derived from Eurotium cristatum. Therefore, fungi contribute to the rich variety of metabolites in brick dark tea. This research can provide a theoretical reference for a comprehensive understanding and knowledge of the chemical basis of quality in typical brick dark tea in China.

The objective of this study was to evaluate the reproduction and production performance and meat quality characteristics of KBF4, a crossbreed of South African Kalaha (SK) and Guizhou black (GB) goats (5/11 SK lineage and 11/16 GB lineage), which was developed through molecular breeding and hybridization after four generations of breeding in six years. KBF4 showed overall improved production performance and meat quality, which were between those of its parents. The lambing rate (LR), survival rate (SR), daily weight gain (DWG) during the first three months of age, adult body weight (ABW), and dressing percentage (DP) of KBF4 were 195.0%, 95.3%, 275.5 g, 55.8 kg, and 53.5%, respectively. The pH of the meat of KBF4 was higher than that of its parents, which corroborated the meat of KBF4 had lower drip loss (DL) and moisture content (MC). In addition, the meat of KBF4 showed decreased ash content of decreased and increased contents of crude protein (CP) and intramuscular fat (IMF) compared with the parents. The amino acid score of the meat of KBF4 was lower than that of its parents, but the amino acid composition and the taste profile were basically consistent with those of SK, and KBF4 was slightly inferior to GB in terms of sweet and umami taste. The contents of essential fatty acids (EFA), monounsaturated fatty acids (MUFA), and polyunsaturated fatty acids (PUFA) increased in the meat of KBF4 compared with its parents, and the contents of beneficial fatty acids including oleic acid, palmitoleic acid, linoleic acid, arachidonic acid, alpha-linolenic acid, eicosapentaenoic acid (EPA), and docosahexaenioc acid (DHA) increased compared with GB. The hypocholesterolemic fatty acid (DFA) values of KBF4 increased significantly, while the arteriosclerosis index (AI), thrombosis index (TI), and n-6/n-3 PUFA ratio decreased significantly compared with those of GB, indicating a reduced cardiovascular disease risk. The major factors influencing the meat quality of KBF4 and its parents included DWG, MUFA, taste-active amino acids (AA), SFA, MC, EFA, PUFA, ABW, DP, CP, DL, IMF, and aromatic AA. In conclusion, KBF4 exhibited greatly improved production efficiency and enhanced meat quality in terms of tenderness, juiciness, and nutrition. Its amino acid and fatty acid composition was more similar to that of SK overall.

In order to further explore flavor peptides and their structure-activity relationship, umami peptides from Yangjiang Douchi were separated and purified by successive alcohol precipitation method, ultrafiltration and ion exchange resin adsorption. The amino nitrogen content, succinic acid content, nucleotide content, relative molecular mass distribution of peptides and free amino acid composition of the obtained fractions were compared. In addition, sensory evaluation and electronic tongue were used to verify the taste characteristics of each fraction. Ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was used to identify the amino acid sequences of the best flavor peptides. The results showed that among the fractions obtained alcohol precipitation and ultrafiltration (E1, E2, E3, E4, A1, A2 and A3), E3 and A3 were the best ones in terms of umami. Fraction A3-I, which was obtained after purification using XAD-7 ion exchange resin, had the strongest umami taste with an umami value of 7.65. Finally, through identification and molecular docking screening, the peptide sequence with the best umami taste was found to be TYDGDTEP. This study provides a theoretical basis and reference for the separation of flavor peptides from Douchi and further exploration of its flavor pattern.

This study was undertaken in order to evaluate the effects of different processing techniques, namely, enzyme-assisted cold-pressing, Soxhlet extraction and aqueous enzymatic extraction on the basic physicochemical properties, antioxidant activity, fatty acid composition, spectral characteristics and volatile flavor substances of corn germ oil. The results showed that the acid value and peroxide value of corn germ oil obtained by enzyme-assisted cold pressing were higher than those obtained by the other methods. The hydroxyl radical scavenging ability of the oil obtained by enzyme-assisted cold pressing was the highest, and there was no significant difference in the contents of linoleic acid, linolenic acid or unsaturated fatty acids oil among the three oil samples. The full spectrum analysis showed that the highest content of linolenic acid (conjugated trienoic acid) was found in the oil obtained by aqueous enzymatic extraction. The composition and relative content of volatile compounds in corn germ oil varied significantly with the different production processes. In summary, the processing methods can affect the physicochemical properties, antioxidant properties and flavor substances of corn germ oil, which provides a theoretical reference for the utilization of corn processing by-products and the moderate processing of corn germ oil.

Liquid smoke processed by thermal pyrolysis at 450 ℃ under nitrogen protection was prepared as a flavoring agent from peach wood. Its effect on the flavor characteristics and consumer acceptability of sirloin steak was investigated. Various liquid smoke concentrations and marination times were applied to the smoking process. Sensory descriptors were summarized by focus group tests and illustrated by a word cloud method. Flavor evaluation was carried out using check-all-that-apply questions and principal component analysis (PCA). Results showed that the liquid smoke significantly improved the sensory descriptors of steak, including mild smokey, barbequed, cooked beef-like and meaty flavors, dark color, chewy and juicy texture. Correlation analysis showed that both the overall preference and odor preference were positively correlated with the flavor preference. Chemical analysis showed that the liquid smoke at low concentrations used in this study did not have significant effect on the moisture content, fat content or pH of steak.

To address the issue of the poor antioxidant and preservative effects of gallic acid (GA) on the quality of aquatic products due to its poor water solubility, a novel water-soluble GA derivative GA-CONH-SO3H was successfully synthesized and confirmed by high resolution mass spectrometry (HRMS), nuclear magnetic resonance (NMR), and spectroscopy. Theoretical calculations of non-covalent interactions (NCI) revealed that GA-CONH-SO3H exhibited abundant hydrogen bonding to water molecules, with binding energy stronger that than of GA. Moreover, the measured saturation solubility of GA-CONH-SO3H in water at room temperature was 290.02 mg/mL, which was 26-fold higher than that of GA. Meanwhile, the 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxy, and superoxide anion radical scavenging capacities of GA-CONH-SO3H were 92.80%, 98.09% and 99.74%, while those of GA at 58.78 μmol/L, 1.76 mmol/L and 23.51 mmol/L were only 89.77%, 49.56% and 29.89%, respectively. After 8 days of storage at 4 ℃, the pH of shrimp (Litopenaeus vannamei) soaked in GA-CONH-SO3H solution was 7.44 compared to 7.71 with GA, and after 6 days, the total volatile basic nitrogen (TVB-N) content, thiobarbituric acid reactive substances (TBARS) value were total viable count (TVC) were 27.07 mg/100 g, 0.87 mg/kg and (5.09 ± 0.02) (lg(CFU/g)) as opposed to 35.47 mg/100 g, 0.94 mg/kg and (5.66 ± 0.03) (lg(CFU/g)) with GA, which indicated that the preservative effect of GA-CONH-SO3H was significant. It extended the shelf life by 2 days. Additionally, GA-CONH-SO3H was significantly superior to 4-hexylresorcinol (4-HR) as a commercial fresh shrimp preservative in inhibiting the increase of TVB-N, TBARS and TVC values. Furthermore, GA-CONH-SO3H exhibited very low cytotoxicity. Therefore, GA-CONH-SO3H has great potential as an antioxidant preservative for aquatic products.

In this study, to investigate the effects of melatonin on pericarp browning in rambutan fruit, postharvest ‘Baoyan7’ rambutan fruit was immersed in melatonin solutions at varying concentrations for 15 min, air-dried, and then stored at 25 ℃ for 6 days. The results demonstrated that melatonin treatment at each concentration delayed browning and the decline in the chromaticity a* value of rambutan pericarp, with the most pronounced effect being observed at 0.125 mmol/L melatonin. Physiological and biochemical analyses showed that melatonin treatment at 0.125 mmol/L repressed the increase in relative conductivity (RC) and malondialdehyde (MDA) contents, while retarding the increase in lipoxygenase (LOX), lipase (LPS) and phospholipase D (PLD) activities in rambutan fruit during storage, thereby preserving the integrity of the cell membrane. In addition, treatment with 0.125 mmol/L melatonin increased the contents of nicotinamide adenine dinucleotide (NADH) and flavin dinucleotide (FADH2), enhanced the activities of energy metabolism-related enzymes including succinate dehydrogenase (SDH), cytochromic c oxidase (CCO), H+-ATPase and Ca2+-ATPase, and maintained high levels of adenosine triphosphate (ATP) and energy charge, thus improving cellular energy status. Moreover, this treatment enhanced γ-aminobutyric acid (GABA) content, and maintained high activities of glutamate decarboxylase (GAD) and GABA aminotransferase (GABA-T), thus contributing to enhanced cellular energy supply. These findings suggest that melatonin could retard postharvest browning and senescence in rambutan fruit by modulating membrane lipid and energy metabolisms.

Two-dimensional near-infrared (2D-NIR) correlation spectroscopy integrated with droplet analysis was used for comprehensive evaluation of the storage quality of blueberries. NIR spectra and droplet fingerprints of ‘Emerald’ blueberries with 8 storage periods were collected, and 15 physicochemical indexes such as hardness, anthocyanin content, VC content and solid/acid ratio were considered, among which a close correlation was found. Therefore, membership function analysis (MFA) combined with principal component analysis (PCA) was employed to calculate comprehensive scores for blueberries from the 15 physicochemical indexes, and based on the comprehensive scores, the storage quality of blueberries was graded. The spectral data were preprocessed by Savitzky-Golay (SG) convolutional smoothing, standard normal variate (SNV) transformation, multiple scattering correction (MSC) or adaptive iteratively reweighted penalized least squares (airPLS). After comparative analysis, it was found that SG convolutional smoothing yielded the highest predictive model accuracy of 82.67%. After averaging and dimensional reduction, the droplet data were preprocessed by SG convolutional smoothing, Gauss filtering or median filtering. SG convolutional smoothing was found to provide the highest predictive model accuracy of 86.67%. Using the comprehensive scores of blueberries as the external disturbance, two-dimensional correlation analysis was carried out on the spectral and droplet data, and the positions of the autocorrelation peaks at 879, 1 019, 1 220 and 1 636 nm and at 789, 1 653, 2 386 and 2 703 ms were selected as the feature variables, respectively. Support vector machine (SVM) and random forest (RF) models were established using the fusion of spectral and droplet feature data as the input, and the predictive accuracy of the models were 100.00% and 98.33%, respectively, which were higher than those obtained using the single features as the input; the SVM model had a better prediction effect than the RF model. Then, nine blueberry varieties such as ‘Sapphire’, ‘Legacy’ and ‘Bluecrop’ were used for validation of the SVM model established using a series of data processing methods. The results showed that the SVM model exhibited good predictive effects for all varieties. Therefore, visible/near-infrared spectroscopy combined with droplet analysis enables the prediction of the comprehensive storage quality of blueberries, providing a new method for the quality evaluation of blueberries.

In this study, the fluorescence hyperspectral images of plastic packaging surfaces in the wavelength range of 421–700 nm were collected using fluorescence hyperspectral imaging (F-HSI) technique with ultraviolet (UV) light at 365 nm as the excitation light source. The characteristic fluorescence spectra of Escherichia coli contamination on the surface of various plastic packaging materials (polyethylene (PE), polypropylene (PP), and polyamide (PA)) were determined and the detection limit for the biofilm of E. coli was established. The results showed that the characteristic fluorescence wavelengths of E. coli on PE, PP and PA surfaces were 550, 543, and 540 nm, respectively. Based on the processed single-band images at these characteristic wavelengths, E. coli inoculation points on the surface of the three plastic packaging materials could be accurately detected, and the detection rates were all greater than 98%. The detection limits of E. coli biofilm on PE, PP and PA surfaces were 1.39, 1.39 and 1.59 (lg (CFU/cm2)), respectively. The research results provide a powerful technical means and theoretical support for microbiological detection of packaged foods and food safety monitoring.

Microorganisms are often affected by various environmental stresses (such as acid, heat, salt and oxidation) in the production and processing of fermented foods. Cross-protection refers to the phenomenon in which microorganisms are induced to increase stress tolerance after subjected to certain stresses. Improving microbial environmental tolerance with cross-protection is of great significance for improving the functional characteristics of microorganisms and promoting the development of the fermented food industry. In this paper, the cross-protection of microorganisms in fermented foods is reviewed. Furthermore, the response mechanisms of microbial cells under cross-protection are summarizes from the aspects of the cell wall and membrane barrier system, the intracellular pH regulation system, and the protein and amino acid regulation system, and possible strategies are suggested to improve the stability of microorganisms under stress conditions.

Signal transducer and activator of transcription 3 (STAT3) exists in the cytoplasm, nucleus, mitochondria, and mitochondria associated endoplasmic reticulum membranes, which is a signal transduction protein involved in various physiological processes such as cell proliferation, differentiation, migration, and immune regulation. This article provides an overview of the structures and types of STAT3 and the pathways through which STAT3 enters mitochondria, and elaborates on the regulatory effect of STAT3 on cellular homeostasis including the anti-apoptotic effect mediated by endoplasmic reticulum Ca2+ transport, the mechanism of action in maintaining mitochondrial function, and the regulatory mechanism on lipid synthesis and catabolism. Furthermore, this paper explores the regulatory mechanism of STAT3 on meat color from the perspective of regulating hematopoietic stem cells, skeletal muscle, mitochondrial homeostasis, and lipid synthesis and metabolism in order to provide a theoretical reference for improving meat color.

Processed cheese is very popular among consumers because of its rich taste, stable quality, and easy portability, but the high fat content in processed cheese cannot meet the demand of health-conscious consumers for low-fat foods. Therefore, the production of processed cheese with low-fat content has become a trend in the dairy industry. However, the reduction of fat affects the quality of cheese to a certain extent. How to improve the quality characteristics of low-fat processed cheese is an urgent problem in the dairy industry. Fat substitutes are intended to imitate the fat in cheese while compensating for the defects in the flavor, texture and other quality characteristics of cheese due to the reduction of fat. Therefore, in order to provide a reference for the development of low-fat processed cheese and to promote further development of the cheese industry, this article reviews the important roles of fat and different fat substitutes (fat-, protein-, and carbohydrate-based substitutes) in the flavor, texture and other quality characteristics of cheese and low-fat processed cheese, and summarizes approaches to enhancing the quality of low-fat processed cheese.

Low concentrations of exogenous ethylene are one of the major causes for the quality deterioration of postharvest fruits and vegetables. Efficient removal of exogenous ethylene is key to solving this problem. At present, low-temperature catalytic oxidation technology is the most safe, efficient and economical method for removing low concentrations of exogenous ethylene in fruit and vegetable preservation scenarios. This review article focuses on the application of low-temperature ethylene oxidation catalysts in fruit and vegetable preservation, analyzes the mechanism of ethylene catalytic oxidation at low temperatures, and summarizes recent developments and future trends of various noble metal catalysts (Au, Ag, and Pt based catalysts). Moreover, based on the issue of catalyst deactivation, the reasons for the deactivation of low-temperature ethylene oxidation catalysts at low temperatures are discussed and possible solutions to solve this problem are presented. Finally, we give an outlook on the future development of low-temperature ethylene catalysts in order to provide assistance and new ideas for the development of stable and efficient low-temperature ethylene oxidation catalysts.

Jam, as a common processed fruit product, has a long history of consumption and is widely loved by consumers due to its diverse products and rich nutrition. The texture of traditional jam can only be formed under high sugar (55%–75%) and highly acidic (pH 2.0–3.5) conditions, which is a challenge for the production of low-sugar jam. In addition, the texture of jam is vulnerable to damage during transport and storage, leading to jam quality deterioration. Food thickeners, food additives that increase the viscosity, consistency and gel strength of liquid foods, are widely used for promoting the formation of the texture of low-sugar jam and maintaining its stability during transport and storage. In this article, the deterioration phenomenon and formation theory of jam texture are reviewed. The thickening or gelling mechanism of food thickeners (e.g., pectin) and their application in jam are described with a focus on the effects of food thickeners on the sensory attributes, texture, rheological properties, and microstructure of jam. Moreover, several possible future research directions are proposed, aiming to provide ideas for the development and application of thickeners in jam.

This review summarizes the application of machine learning in research on the numbing substances of Zanthoxylum bungeanum. Different varieties of Z. bungeanum on the market vary in the composition and content of numbing substances. Traditional methods for the detection and analysis of the composition and content of numbing substances in Z. bungeanum have many limitations, so the introduction of machine learning algorithms has brought new possibilities to this field. Applying machine learning for predictive modeling of the quality of Z. bungeanum and modeling of its drying process, the sensory evaluation of Z. bungeanum, and establishing a germplasm bank for Z. bungeanum is of great significance for the genetic breeding of Z. bungeanum. This article systematically reviews the composition and content of numbing substances in different varieties of Z. bungeanum, and analyzes the application of machine learning algorithms in predictive quality modeling and drying modeling of Z. bungeanum and data analysis of its numbing substances. Integration with machine learning technology enables a deeper understanding of the currently established models, which will provide support for the optimization of the yield and quality of Z. bungeanum based on numbing substances.

Sunflower seed meal, a by-product of sunflower seed oil production, is a high-quality protein source that is nutritious in terms of abundant protein, has reasonable amino acid composition and is hypoallergenic. At present, most reviews on sunflower seed meal focus on the fields of its processing and application status, comprehensive utilization, active ingredients, modification technologies and application in feed. However, due to the presence of polyphenols (mainly chlorogenic acid), sunflower seed meal is susceptible to browning during preparation and processing, which seriously restricts its deep development and utilization. The major techniques for the removal of chlorogenic acid from sunflower seed meal include water extraction, organic solvent extraction, physical field assisted method, enzymatic method, salt inhibition method and resin adsorption, but they have been scarcely reviewed systematically. In this paper, we review the latest research progress on the composition of sunflower seed protein, its interaction with chlorogenic acid, the removal methods of chlorogenic acid from sunflower seed meal, and the application of sunflower seed protein in the food field in order to provide a reference for further processing and utilization of sunflower seed meal.

With the realization of “Space 180”, as well as the proposal of the “Space Home Port” program and the manned Mars exploration program, taikonaunts have gradually undertaken more long-term missions in deep space. Therefore, the supply technology of space foods is facing new challenges. Three-dimensional printing technology, also known as additive manufacturing technology, provides a new idea to solve space food problems because of its ability to produce highly customized and personalized foods. Through research and analysis, this article introduces common 3D food printing methods, systematically discusses the application of 3D printing technology in the design and production of space food shapes and the regulation of nutrients and flavor as well as its advantages in enabling the long-term storage and transportation of space foods, and points out the unique challenges of 3D printed food production in the space environment, including printing and shaping under microgravity conditions, and the impact of cosmic radiation on materials and equipment. Finally, an outlook on future trends and directions for 3D printed space food technology is provided, aiming to provide a reference for space food innovation.

Ferulic acid (FA), the most abundant phenolic acid in cereals, widely exists in both free and bound forms in grains, legumes and other plant-based foods. FA has various functional activities, such as antioxidant, anti-inflammatory and antibacterial properties, thus exhibiting high application values in the fields of food and medicine. To date, although a large number of in vivo and in vitro experiments have shown the importance of cereal FA in maintaining intestinal health, it is still unclear how FA is metabolized by the gut microbiota. In order to offer new insights into the molecular mechanism of the regulatory effect of FA the gut microbiota and offer a theoretical reference for better development and utilization of cereal FA and its metabolites, this paper provides a systematic review of the recent literature concerning intestinal microbial metabolism of cereal FA from three aspects of the existing forms, intestinal release and metabolism, and physiological health effects.

Cow milk protein is a common food allergen, and cow milk allergy (CMA) has become a common public health problem around the world. Exploring the mechanism of allergy to cow milk protein and developing green and efficient techniques to reduce its allergenicity have become important research topics in the field of foods. In this article, the antigenic epitopes of cow milk allergens are summarized, and the mechanisms and symptoms of cow milk allergy are introduced. The effects and potential mechanisms of different processing techniques (such as thermal processing, high pressure, ultrasound, glycosylation, coupling with polyphenols, enzyme treatment, fermentation and transgenic technology) on the allergenicity reduction of cow milk protein are discussed, and an outlook on future developments in cow milk allergenicity reduction techniques is given.

Saponins are the primary secondary metabolites of sea cucumber, which are the material basis for its chemical defense. Sea cucumber saponins possess multiple biological properties including antitumor activity, immunoenhancing effect and ameliorative effect on metabolic syndrome, and therefore hold great promise in the development of health products and drugs. Sea cucumber saponins are complex and diverse, and their structural characteristics greatly affect their biological activities. This review begins with an overview of the sources and types of sea cucumber saponins, and then focuses on systematically summarizing the current status of research on their structural characteristics, bioactivities and action mechanisms. Finally, it gives an outlook on future prospects. We expect this review will provide a reference for the high-value development and utilization of sea cucumber saponins.

Magnetic ionic liquids (MILs), as a type of magnetic functionalized ionic liquid materials, are characterized by low vapor pressure, wide liquid range, and excellent thermal stability and possess strong designability, easy product separation, and recyclability for repeated use. These properties enable them to tackle problems with microextraction techniques such as difficult phase separation and low reusability. MILs have a broad application prospect in the field of sample pretreatment for food analysis. This article systematically summarizes the varieties and preparation methods of MILs for sample pretreatment for food analysis, reviews recent progress in the application of MILs in the separation and enrichment of various chemical contaminants in foods, including bioamines, drugs, food additives, persistent toxic substances, and inorganic heavy metals. It concludes with an outlook on the future development of MIL-based sample pretreatment techniques for food analysis.

Digital polymerase chain reaction (dPCR) is a novel nucleic acid amplification technology that enables absolute quantitative analysis of nucleic acid at the single-molecule level through extreme dilution and Poisson distribution statistics without any need for internal reference genes or standard curves. It has the advantages of high sensitivity, accuracy and tolerance, and has great development potential in the field of food safety detection. This paper introduces the technical principle, advantages and disadvantages, and commercial platforms of dPCR, and summarizes recent progress in the application of dPCR in the fields of foodborne pathogen detection, animal- and plant-derived component detection, genetically modified component detection, and foodborne virus detection and the current status of the standardization of dPCR. The problems existing in this technology and possible future development directions are discussed. We hope that this review can provide ideas for promoting the application of dPCR in food safety detection and formulating a standard for dPCR.

Food safety concerns the life and health of people, which raises higher requirements for food safety regulation. The law enforcement departments should attach great importance to food safety issues, and effectively strengthen food safety enforcement by various means and measures to ensure safe food for people. At present, there are many problems in China’s food safety regulation, leading to insufficient law enforcement and single means of supervision. In this context, the whole process of food production should be supervised in food safety enforcement. This article starts with an analysis of the food safety supervision model in China, and then discusses how to improve it, aiming to provide a reference for relevant personnel.