To clarify the formation mechanism of soybean protein nanofibrils and broaden the industrial application of iron fortifiers, nanofibrils were prepared by heating soy protein isolate (SPI) for five hours under acidic conditions in the present study. Changes in protein structure before and after fibrillation were systematically investigated. Furthermore, iron nanoparticles (Fe NPs) were prepared and the stabilizing effect of SPI nanofibrils on them was evaluated. The results showed that during the formation of SPI nanofibrils, a considerable amount of β-sheet structure was produced and combined with thioflavin T, increasing the fluorescence intensity. In addition, the degradation of 7S fraction was observed at the early stage, being conducive to the formation of fibril nucleation, and then 11S was gradually hydrolyzed, promoting fibril growth. Meanwhile, a large number of small peptides were produced, improving the reducing power of the hydrolysate. SPI nanofibrils were used to deliver Fe NPs. It was found that Fe NPs and SPI nanofibrils could form in situ a complex with good colloid stability, existing as Fe (II) and having less influence on the color and stability of emulsions compared with ferrous sulfate and ferric chloride. The results of the present study should guide the construction of a new plant-based iron delivery system.

The effect of two-stage heating mode on the properties of silver carp surimi gel added with glucose oxidase (GOD) was studied. The results showed that at the gelation stage, the gel strength, water-holding capacity, whiteness and immobile water content of surimi were the highest under the high-temperature short-time (40 ℃/1 h) mode, and the free water content was the lowest, and the gel network formed was the most compact. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) pattern showed that the strength of myosin heavy chain (MHC) was reduced under the high-temperature short-time mode, suggesting that the protein was degraded more under this condition. At the maturation stage, microwave heating provided the highest gel strength, water-holding capacity and whiteness and the smallest trichloroacetic acid (TCA)-soluble peptide content, free water content and equivalent pore size, and resulted in the formation of an orderly and dense three-dimensional network. The SDS-PAGE pattern showed that compared with water bath heating, the intensity of MHC was higher under microwave heating, suggesting that microwave heating promotes the formation of disulfide bonds. Therefore, a suitable heating mode can improve the quality of surimi gel.

In this study, dumpling wrappers were made from wheat flour with different amounts of purple sweet potato anthocyanins (PSPA) added. The structural characteristics of wheat gluten proteins and the quality of dumpling wrappers were investigated using Fourier transform infrared spectroscopy, laser confocal Raman spectroscopy, a rheometer, and a texture analyzer. The results showed that the antioxidant activity of dumpling wrappers was improved by adding different amounts of PSPA. The interaction between PSPA added at levels of 0.1%–0.4% and wheat gluten proteins gradually increased the α-helix content and enhanced the orderliness and stability of the gluten network, thereby improving the hardness, chewability and tensile resistance and reducing the cooking loss of dumpling wrappers. However, when the addition amount increased to 0.8%, the reducibility and antioxidant properties of polyphenols played a major role in the destruction of disulfide bonds, thereby weakening the gluten network, reducing the hardness, thus increasing the cooking loss of dumpling wrappers.

The goal of this study was to investigate the effect of whether or not whey protein concentrate (WPC) is involved in starch gelatinization and WPC concentration on the lubricating properties of a starch-WPC mixed system as evaluated using polydimethylsiloxane as the friction pair under simulated oral conditions. The results showed that during the first 60 seconds of oral processing, the lubricating properties of starch-WPC mixed systems significantly varied depending on whether or not WPC was involved in starch gelatinization and on the species of starchy plants used (P < 0.05). Addition of 1%–7% of WPC significantly improved the lubricating properties of starch gels in a nonlinear manner (P < 0.05). The results of this study provide a theoretical basis for improving the texture and taste of starch-protein based foods.

In this study, chitosan microflowers (CSMF) were prepared by an ionic cross-linking method and were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). The loading capacity of CSMF for procyanidins (PC) as a model drug under different conditions was investigated, and the in vitro sustained release and antioxidant properties of procyanidins-loaded microflowers (PC-CSMF) were analyzed. The results showed that the morphology of CSMF was a three-dimensional multi-layer micro-flower structure with a diameter of approximately 1.5 μm, and there was a gap between layers. The FTIR spectrum of PC-CSMF showed an absorption peak at 1 448 cm-1, and XPS showed that the ratio of carbon to oxygen on the surface of PC-CSMF increased, which proved that PC was successfully loaded onto CSMF. The results of X-ray diffraction (XRD) and thermogravimetric analysis (TG) demonstrated that the crystallinity and thermal stability of PC-CSMF did not change significantly. The results of single factor experiments showed that the maximum PC load of CSMF of 352.88 mg/g was obtained at room temperature (27 ℃) and a PC concentration of 10 mg/mL. PC-CSMF had sustained release properties and antioxidant activity in vitro.

In order to provide basic data for delaying quality deterioration in waxy corn, the microstructure and physicochemical properties of waxy corn starch isolated from fresh and frozen corn (stored at ?18 ℃ for 10, 20 or 30 days) were investigated by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffractometry (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and a rapid viscosity analyzer (RVA). The results showed that frozen storage decreased the ratio between the IR peaks at 1 045 and 1 022 cm-1 (R1 045/1 022) and the relative crystallinity of waxy corn starch, and increased the full width at half height. After frozen storage, pits and cracks appeared on the surface of the starch granules, and their size became smaller. As frozen storage time increased, the microstructure of corn starch was damaged more seriously. After frozen storage, the gelatinization temperature, gelatinization enthalpy, peak viscosity and breakdown value of waxy corn starch decreased, while the final viscosity and retrogradation value increased, indicating that frozen corn starch was more prone to gelatinization and retrogradation. In addition, frozen storage could convert slowly digestible starch and resistant starch into rapidly digestible starch, thereby having the potential to improve the digestion rate and degree of fresh corn.

In this study, the effects of diglyceride (DAG) content, baking temperature, addition of salt and baking duration on the contents of 3-monochloropropane-1,2-diol esters (3-MCPDE), glycidyl esters (GE), hardness and gumminess of soda biscuit prepared with diglyceride-rich olive oil were evaluated. The results showed that the highest contents of 3-MCPDE and GE in soda biscuit were 1.05?and 0.37?mg/kg, respectively. Moreover, it was found that the content of 3-MCPDE was positively correlated with the baking temperature and salt addition, and GE content increased with increasing baking temperature up to 170 ℃. However, the production of 3-MCPDE and GE were not significantly (P > 0.05) related to the content of DAG and baking duration. In conclusion, diglyceride-rich olive oil can be safely used in soda biscuit and can improve its texture. In addition, controlling baking temperature and salt addition can reduce the contents of 3-MCPDE and GE in soda biscuit.

The lipid profiles of raw, pasteurized and fermented cow milk and goat milk were investigated using lipidomics based on ultra-high performance liquid chromatography (UPLC) coupled with quadrupole tandem electrostatic field orbitrap mass spectrometry. A total of 27 lipid subclasses were detected in all samples, including 1 607 lipid molecules. The results proved that pasteurization had no effect on the lipid profiles of cow milk or goat milk, while fermentation had a significant influence on the lipid profiles of cow milk and goat milk; in particular, it greatly reduced the content of hemolytic phospholipids. Totally 27 and 23 lipid molecules which could be used as potential biomarkers for the identification of pasteurized and fermented milk were selected. This study has provided an understanding of the lipid profile and dynamic changes in the fermentation process of milk, which can provide a molecular basis for understanding the effects of heat treatment and fermentation on milk fat during yogurt processing and be helpful to understand the quality and nutritional characteristics of yogurt products.

This study aimed to analyze the effect of glycerin monostearate (GMS) on the emulsion stability of recombined dairy cream (RDC) formed with micellar casein (MCN), calcium caseinate (CaC) or sodium caseinate (NaC). The results showed that GMS could change the particle size distribution of lipids droplets by co-adsorbing onto the oil-water interface together with caseins and consequently the emulsifying stability of RDC. For MCN-RDC, a significant increase was observed in the phase separation time after GMS addition, and 2.5% MCN-RDC exhibited the best emulsion stability and an increase in the phase separation time from 474 to 4 622 s. The phase separation time of 0.5%–2.0% CaC-RDC was in the range of 167–483 s, and increased to 177–517 s after GMS addition, whereas that of 2.5% CaC-RDC decreased slightly. The phase separation time of 0.5% NaC-RDC increased from 1 245 s to 1 460 s after GMS addition, while that of NaC-RDC with NaC concentration higher than 1.0% decreased. In conclusion, GMS can increase the emulsion stability of MCN-RDC, and its effect on the emulsion stability of CaC-RDC and NaC-RDC differs depending on the concentration of caseins. GMS can increase the emulsion stability of RDC only when the concentrations of CaC and NaC were 0.5%–2.0% and 0.5%, respectively.

The objective of this study is to investigate the effect of addition of different levels of hydrocolloids (flaxseed gum or Artemisia sphaerocephala Krasch. gum) on the physicochemical properties of glutinous rice flour and the quality of the resultant sweet dumplings. The results showed that the addition of hydrocolloids except 0.1% of flaxseed gum could improve the peak viscosity, trough viscosity and final viscosity of glutinous rice flour in a concentration-dependent manner. Moreover, the elastic modulus and viscosity modulus of glutinous rice flour were increased, and the loss tangent was decreased, which was conducive to the formation of a highly stable gel structure. In addition, the addition of hydrocolloids significantly reduced the water loss rate and cracking rate of sweet dumplings and increased the transmittance of the soup (except 0.1% of flaxseed gum) and the hardness of sweet dumplings, indicating that hydrocolloids can improve the quality of sweet dumplings. Fuzzy mathematics was used to standardize the sensory evaluation data of sweet dumplings. It was shown that the sensory evaluation score increased with increasing addition level of hydrocolloids. According to the physicochemical properties of glutinous rice flour as well as using principal component analysis (PCA), a comprehensive evaluation model for the quality of sweet dumplings was established, which can provide a basis for the application of hydrocolloids in sweet dumpling.

In this study, the effect of addition of gallic acid (GA) (0%–0.25%) on the gel properties, microstructure and intermolecular forces of surimi from Nemipterus virgatus, prepared by a two-step heating method, was investigated. The surimi was digested under in vitro gastrointestinal conditions and evaluated for antioxidant activity and cholesterol-lowering activity in order to determine the improving effect of GA addition on the functional properties of surimi gels. The results showed that addition of GA could improve the gel strength and texture properties, but worsen the whiteness of surimi gels. Surimi gels with 0.15% of GA had the best texture properties and highest whiteness and water-holding capacity as well as a dense microstructure, and the major chemical force maintaining the gels was disulfide bonds. The results of digestion in vitro showed that addition of GA increased the protein digestibility of surimi gels (P < 0.05), and enhanced the biological activity of the digested products (P < 0.05). The scavenging percentages of the digested surimi gel with 0.15% of GA toward 1,1-diphenyl-2-picrylhydrazine (DPPH) radical, 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) cation radical and hydroxyl radical were increased all 80% (P < 0.05), and the inhibition percentages toward cholesterol esterase and cholesterol micellization were increased to 50.82% and 41.88%, respectively (P < 0.05). These results indicated that surimi with added GA still retained its biological activity after heat treatment and in vitro digestion. Therefore, addition of an appropriate amount of GA can effectively improve the heat-induced gel properties of N. virgatus surimi while retaining its functional properties, which provides a basis for the development of new functional surimi products.

The aim of this study was to verify the feasibility of applying GlutoPeak test (GPT) for rapid evaluation of wheat quality and establish a comprehensive evaluation method for wheat quality traits based on GPT.?Conventional methods and GPT were used to determine 33 quality characteristics of 81 wheat varieties, and principal component analysis (PCA) was used to evaluate their comprehensive quality.?The orthogonal partial least squares (OPLS) method was used to verify the comprehensive quality evaluation model and its relationship with the characteristic indices measured by GlutoPeak, and analyze the correlation between them and the variable importance in the projection (VIP) values.?The results showed that there were extensive genetic variations in the 33 quality traits among wheat varieties, among which the coefficients of variation of starting energy, stabilization energy, stabilization time, stretching area and maximum stretching resistance were all above 60%.?PCA showed that the cumulative contribution rate of the six principal components extracted was as high as 84.221%, which could comprehensively reflect wheat quality information. The function for comprehensive evaluation of wheat quality was established as follows: Y = 0.283F1 + 0.214F2 + 0.183F3 + 0.130F4 + 0.122F5 + 0.066 3F6, where the correlation coefficients (R2) between AM and PM and the comprehensive quality evaluation score were 0.706 1 and 0.739 2, respectively. Correlation analysis among 18 indicators that significantly affected the comprehensive evaluation score of wheat quality showed that there were significant or extremely significant correlations between the GPT indicators and wheat grain quality attributes and dough rheological properties. This study confirmed the feasibility of using GPT to quickly evaluate wheat quality, which can provide a basis for an accurate understanding of wheat quality, the establishment of wheat quality evaluation criteria and wheat quality control.

In the present study, soybean protein isolate (SPI) was hydrolyzed by alcalase for up to 24 h. It was found that controlled enzymatic hydrolysis could induce the self-assembly of SPI to form a series of homogeneous spherical soy protein nanoparticles (SPNs) with different surface properties that were uniformly distributed (polydispersity index (PDI) < 0.3) ranging from 90 to 200 nm, and that the degree of hydrolysis (DH) and the disassociation/degradation of subunits were the key factors affecting the assembly process. At the initial stage of enzymatic hydrolysis (10–30 min, DH~3%), the α and α’ subunits of β-conglycinin (7S) were partially degraded, thereby being beneficial to release the amphipathic structure, improve the protein surface hydrophobicity (H0) and reduce the critical aggregation concentration and ultimately resulting in the formation of type I nanoparticles (SPNs-DH 3%) containing relatively complete 7S and glycinin (11S) subunits. As the hydrolysis time increased from 1 to 2 h, the α and α’ subunits were further degraded, promoting the exposure of the hydrophobic β subunits and the B subunits, enhancing the hydrophobic interactions and consequently the system’s turbidity, and ultimately leading to the formation of soluble aggregates. The soluble aggregates could transform into insoluble hydrophobic ones, leading to a sharp decrease in the protein surface hydrophobicity and the formation of type II hydrophilic nanoparticles (SPNs-DH 5%) dominated by the A subunits and part of the β subunits. At the late stage of hydrolysis (4–24 h), the A subunits were further degraded to produce more hydrophilic peptides, which was not conducive to the formation of nanoparticles. The circular dichroism spectrum implied that transformation from α-helix and random coil to β-sheet might facilitate the formation of SPNs. Moreover, both type I and II SPNs were mainly maintained by hydrophobic interactions, while hydrogen and disulfide bonds were responsible for the surface and internal structure of the particles, respectively. More folded structures were stabilized by disulfide and hydrogen bonds formed in SPNs-DH 5% compared with SPNs-DH 3%. In addition, due to the continuous release of antioxidant peptides during enzymatic hydrolysis, the antioxidant activity of the formed SPNs was higher than that of SPI.

The proteomic differences between Pichia kudriavzevii under heat stress and that under heat-salt stress were analyzed by tandem mass tag (TMT)-based quantitative proteomics to identify the key proteins related to improved thermotolerance. The expression of heat shock protein (HSP) 12 and the enzymes related to ergosterol biosynthesis, including ergosterol biosynthetic protein (ERG) 28 and ERG25 was significantly improved by salt stress, thereby contributing to the structural and functional stability of intracellular proteins and the cell membrane under heat stress. Salt stress significantly increased the expression of glutathione S-transferase (GST) Y-2, which played an important role in inhibiting heat-induced oxidative damage of lipids and proteins. Meanwhile, salt stress significantly increased the expression of enzymes related to carbohydrate metabolism and energy metabolism under heat stress, including hexokinase (HK), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), phosphoglycerate mutase 1 (PGAM1), PGAM2, phosphoglycerate kinase (PGK), alcohol dehydrogenase (ADHP), cytochrome c oxidase subunit 6A (COX6A), and V-type proton ATPase subunit c’ (ATP6L), thus contributing to the synthesis of intracellular ATP and improvement of its thermotolerance. The results of this study can provide important technical support for the genetic engineering of thermotolerant yeasts and the improvement of their ethanol production at high temperature.

This study was implemented in order to obtain Tetraplococcus halophilus with the ability to produce umami peptides. A total of 83 strains suspected of being T. halophilus were isolated from 96 naturally fermented soybean paste samples from seven different areas of Liaoning province. Through DNA extraction, 16S rDNA sequencing and comparative homology analysis, 47 of these strains were identified as T. halophilus and were screened for their ability to produce polypeptide, γ-glutamyl transpeptidase and protease and their electronic tongue flavor values. Moreover, factor analysis and factor score comprehensive evaluation were carried out, revealing that T. halophilus LY9-1 had the greatest potential to produce umami peptides. The results of electronic tongue also proved that the fermentation broth of T. halophilus LY9-1 had the highest umami value of 15.05 ± 0.02, as well as protease activity of (85.45 ± 0.03) U/mL, γ-glutamyl transpeptidase activity of (44.23 ± 0.03) U/mL, and polypeptide production of (17.55 ± 0.13) mg/mL.?It is speculated that the strain has a strong umami-enhancing potential. The findings reported here can motivate further research on the umami-enhancing mechanism and encourage the industrial application of T. halophilus LY9-1 to enhance the umami of fermented foods.

This experiment was conducted to investigate the effects of solid (SSF) and liquid-state fermentation (LSF) on the morphology and the production and enzymatic properties of tannase of recombinant Pichia pastoris. It was found that there were large differences between SSF and LSF in terms of the bacterial morphology and the production and enzymatic properties of tannase. The recombinant strain had a higher biomass accumulation in SSF, which was 22.3% higher than that in SMF after 48 h incubation. From scanning electron microscopic (SEM) analysis, it was found that individual cells of the recombinant strain were more prone to aggregation, accompanied by the emergence of biofilm in SSF. For both SSF and LSF, the enzyme production increased first and then decreased with methanol concentration, reaching its maximum at methanol concentrations of 2% and 3%, respectively. Furthermore, tanninases produced in SSF and LSF had different enzymatic properties, and their optimum temperatures were 30 and 20 ℃, respectively. The thermal stability of the former was slightly weaker than that of the latter, whereas no significant difference was found in any other enzymatic property tested. In addition, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis showed that tanninase produced in SSF was modified, which may account for the above differences. In conclusion, the findings of this can provide a theoretical foundation for the efficient preparation of tannase.

In order to study the effect of microbial fermentation on the formation and change of flavor substances in air-dried sausages, commercial mixed-strain starters SHI-59 (Staphylococcus xylose, Pediococcus pentosaceus, and Lactobacillus plantarum), WBL-45 (S. xylose, S. botulinus, and L. sake) and PRO-MIX5 (S. xylose, L. sake, and L. plantarum) were inoculated separately into minced meat and after 12 days of air drying, fermented air-dried sausages were produced and denoted as SHI, WBL and PRO, respectively, and a non-inoculated sample was used as a control. Samples subjected to air drying for 6 and 12 days were analyzed for the content of free amino acids. The flavor changes of air dried sausages during the air drying process were determined by a Heraclesii ultra-fast gas chromatography electronic nose, an electronic tongue and gas chromatography-mass spectrometry (GC-MS). The results showed that as the air drying time increased from six to 12 days, the total amount of free amino acids significantly increased, and the total amounts of free amino acids in SHI, WBL and PRO were 2 409.78, 2 317.74 and 2 655.18 mg/100 g, respectively, significantly higher than that in the control group (2 137.82 mg/100 g) (P < 0.05). The four groups of samples could be clearly distinguished in terms of their smell and taste. The flavor richness of PRO was the strongest, followed by SHI and WBL, which had similar smell and taste, and the control group had the smallest flavor richness. Totally 80, 79, 76 and 83 volatile flavor substances were detected in the control, SHI, WBL and PRO groups, respectively. Esters, aldehydes, alcohols, acids and heterocyclic compounds were the major flavor substances of air-dried sausages. The percentages of esters in SHI (20.6%), WBL (24.13%) and PRO (21.71%) were higher than that in the control (19.13%) group, and the ester content of SHI was the highest (2 271.62 μg/kg). (E,E)-2,4-Nonadienal and 3-methylbutyric acid made the greatest contribution to the flavor of the control and SHI groups. SHI and WBL contained heptanaldehyde with an odor activity value (OAV) greater than 1, responsible for the fruit flavor, while ethyl butyrate (OAV > 1), responsible for the pineapple-like aroma, was unique to PRO. The results showed that the application of PRO-MIX5 was more conducive to improve the flavor and taste of air-dried sausage compared with the other commercial starters.

In this study, lactic acid bacteria (LAB) capable of degrading N-acyl-homoserine lactones (AHLs) signal molecules from Aeromonas sobria were screened from traditional fermented foods and identified. The locations and types of LAB quorum quenching enzymes were explored. The salmon spoilage ability of LAB was evaluated by measuring total bacterial count, water-holding capacity, thiobarbituric acid (TBA) value and total volatile basic nitrogen (TVB-N) content. The results showed that a strain capable of degrading almost 100% of A. sobria-derived AHLs, named as YF-8, was obtained using the 96-well plate method combined with the Oxford cup method. It was identified as Pediococcus pentosaceus. The quorum quenching enzyme of strain YF-8 existed in the extracellular supernatant and had AHL degradation activity under both acidic and neutral conditions. It was preliminarily identified as AHLs-acyltransferase. The crude extract of YF-8 quenching enzyme did not affect the growth of A. sobria at sub-inhibitory concentrations of 2.0, 4.0 and 6.0 mg/mL. In addition, the crude extract could maintain the total bacterial count, water-holding capacity, TBA value and TVB-N value of salmon infected with A. sobria during storage. The results of this study are expected to provide a theoretical basis for the screening of microbial quorum sensing quenchers and aquatic product biopreservatives.

The aim of this study was to evaluate the tolerance of Lactobacillus to digestive stress in simulated saliva, gastric juice and intestinal juice, its adhesion capacity to intestinal mucin and Caco-2 cells and its inhibitory capacity against intestinal pathogen adhesion. The effect of digestive stress on the intestinal adhesion capacity of Lactobacillus was also studied. The results showed that the viable counts of L. paracasei?m111 and W125 and L. fermentum 146 were 7.46, 7.24 and 8.35 (lg(CFU/mL)), respectively, and their survival rates were 2.70%, 3.53% and 11.15%, respectively, after sequential exposure to simulated saliva, gastric juice and intestinal juice. Their adhesion rates to mucin were 15.67%, 8.75% and 8.38%, and their adhesion rates to Caco-2 cells were 11.47%, 21.34%, 10.44%, respectively, which were significantly higher than those of the other strains (P < 0.05). Each of the three strains had the capability to inhibit the intestinal adhesion capacity of Escherichia coli CICC10899 and Salmonella WX29 by exclusion, competition or substitution, with an inhibition percentage of more than 13.51%. Digestive stress significantly decreased the intestinal adhesion capacity of L. paracasei W125 and L. fermentum 146 (P < 0.05), but increased the intestinal adhesion capacity of L. paracasei m111 from 17.60% to 30.45% (P < 0.05). After digestive stress, the major adhesins changed from surface proteins to proteins and polysaccharides, the morphology of L. paracasei m111 remained long spindle-like, round rod-like in shape, whereas the thickness of the surface material was not significant changed (P > 0.05). In conclusion, L. paracasei m111 has strong tolerance to digestive stress and consequently strong intestinal adhesion capacity, making it a potential probiotic with a promising future.

In order to explore the species and functions of microRNAs (miRNAs) in donkey milk exosomes, Illumina sequencing technique was used to sequence the small non-coding RNAs (sRNAs) in donkey milk exosomes, and identify the miRNAs in them through bioinformatic analysis using human milk miRNAs as the control. After quality control, the length of the sRNAs in donkey milk exosomes was mainly distributed between 18 and 22 nt, and a total of 212 miRNAs were identified, including 16 known ones and 196 new ones. Gene Ontology (GO) enrichment analysis showed that the functions of the miRNAs in donkey milk exosomes were similar to those of human milk miRNAs, such as constituting cells, organelles and other components, binding and catalytic activity and participating in the processes of cell metabolism and biological regulation. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that the miRNAs in donkey milk exosomes participated in the synthesis and secretion of aldosterone, the Hedgehog signaling pathway, mitochondrial regulation and cancer pathways.

The bacterial community structure of bacterial-type naturally fermented dried douchi (a Chinese fermented soybean product) produced in Zunyi was analyzed by high-throughput sequencing, and its flavor quality was evaluated. According to the diversity index and the relative abundance of operational taxonomic units (OTUs), it was found that the major bacterial contributor for the bacterial-type douchi was Bacillus, and a small amount of Lactobacillus also played an important role in its fermentation. Therefore, both bacterial species could cooperate to produce douchi with a unique flavor. A total of 16 amino acids including 6 essential ones were identified in the douchi, as well as 26 free fatty acids including 15 saturated ones and 11 unsaturated ones. In addition, the relative contents and thresholds of the major aroma contributors in the douchi were compared using the major volatile substances contributing to the flavor of douchi as references, revealing that the relative content of acids in the douchi was the highest (44.529%), followed by nitrogen-containing substances, and the contents of alcohol, ketone and ester substances were very low. The results of this study can provide a basis for understanding the correlation between the microbial flora structure of bacterial-type douchi and the formation of its flavor substances and for the development of direct vat set starters for douchi.

This study investigated the effect of mixed culture fermentations with non-Saccharomyces strains and Saccharomyces cerevisiae on the aroma quality of ‘Cabernet Sauvignon’ wine from the eastern foothill of Helan Mountain in Ningxia in order to determine the optimum inoculation scheme for mixed culture fermentation. Three non-Saccharomyces strains were tested, including Hanseniaspora uvarum YUN268, Pichia fermentans Z9Y-3 and Pichia kluyveri C735. The proportions of mixed cultures were 10:1 and 1:1 between non-Saccharomyces and S. cerevisiae. Two inoculation schemes were used, namely sequential (48 hours apart) and simultaneous inoculation. Inoculation with S. cerevisiae alone was used as a control. The physicochemical and aroma properties of the resultant wine samples were evaluated. The results showed that compared with the control group, the mixed culture fermentation treatments increased the glycerol yield by 0.38–1.11 g/L and reduced the alcohol content by 0.33%–1.9%. In addition to ensuring successful completion of alcoholic fermentation, simultaneous inoculation of P. fermentans Z9Y-3 and S. cerevisiae at a mixing ratio of 10:1 significantly increase the dry extract content by 23.6% and the glycerol content by 4.6%. Moreover, this inoculation scheme maximized the ability of the two strains to produce aroma compounds, significantly increasing the contents of 30 different aroma compounds, including linalool, β-damascenone, ethyl octanoate, phenethyl acetate, methyl decanoate, isoamyl octanoate increasing the total amount of volatile compounds by 45%, and enhancing the berry-like, tropical fruit-like, floral and nutty aroma of wine. Therefore, this mixed culture fermentation scheme can be used as an ideal one for the production of ‘Cabernet Sauvignon’ wine in the eastern foothill of Helan Mountain.

In order to find out the differences in the microbial community structure in Qula at different altitudes of Tibet, a total of 40 yak Qula samples were collected from three groups at low, middle and high altitude for high-throughput sequencing. The results showed that there were differences in microbial community diversity among the different groups of samples. With the increase in altitude, the diversity and richness of bacterial flora in Qula samples showed a downward trend, and so did the abundance of fungal flora, while the diversity of fungal flora did not change significantly. The samples from the low, middle and high altitude groups contained 2 411, 1 391 and 1 197 bacterial operational taxonomic units (OTUs), respectively, and 715 bacterial OTUs were common to the three groups; the dominant bacterial genera identified were Lactococcus and Lactobacillus, with an average relative abundance of 34.0% and 18.4%, respectively. The samples from the low, middle and high altitude groups contained 801, 343 and 399 fungal OTUs, and 173 fungal OTUs were common to the three groups; the dominant fungal genus identified was Geotrichum, with an average relative abundance of 33.8%. The results of this study can provide a theoretical basis for the selection and utilization of characteristic microbial resources in Qula.

This study aimed to develop a core-shell carrier based on natural plant microcapsules for use as a delivery system for Lactobacillus plantarum and β-galactosidase (β-Gal). Sporopollenin exine capsules (SECs) were used as the core, and calcium-alginate (Ca-Alg)/carboxymethylpachymaran (CMP) as the shell. The probiotics loading capacity and the residual activity of β-Gal were 9.63 × 109 CFU/g and 80.72%, respectively. The introduction of CMP could affect the swelling behavior and microstructure of the shell and, consequently, the release behavior of probiotics and enzymes by changing its water-binding capacity. The introduction of CMP improved the gastrointestinal stability of Ca-Alg/CMP coated SECs loaded with L. plantarum and β-Gal. After 600 min of culture under simulated gastrointestinal conditions, the number of viable cells exceeded 107 CFU/mL, and the residual activity of β-Gal was around 62%. Compared with the control group (pure L. plantarum and β-Gal), the system could significantly reduce the loss rates of the probiotic cell count and β-Gal activity after lyophilization and during storage (P < 0.05). Finally, using methylcellulose (MC) to coat the core-shell structure could significantly improve the thermal stability of L. plantarum and β-Gal (P < 0.05).

The fungal community diversity and structure in different colored Jiang-flavor Daqu (yellow, black and white) were investigated by high-throughput sequencing, and the reason for the physicochemical differences between the three Daqu was analyzed. The results showed that the liquefying power of yellow Daqu (YQ) was higher than that of black Daqu (BQ) and white Daqu (WQ), and the fermenting and esterifying power of YQ (1.56 and 22.63 U, respectively) and BQ (1.51 and 22.48 U, respectively) were higher that those of WQ. The dominant fungi in YQ and BQ were Aspergillus, Cladosporium and Phylctinia, while those in WQ were Aspergillus, Thermoascus, and Byssochlamys. In addition, the fungal community structure and species abundance in YQ were similar to those in BQ. Nonetheless, WQ had a great difference in fungal community structure at the genus level from, and low similarity of species to YQ and BQ. Linear discriminant effect size (LEFse) analysis showed that the fungal community structure of different colored Jiang-flavor Daqu differed in terms of Saccharomyces, Thermoascus, Byssochlamys and several other genera with low abundance. The results of this study lay the foundation for the application of functional fungi in Jiang-flavor Daqu, and provide theoretical support for improving the fermentation performance of Jiang-flavor Daqu.

The antioxidant activity of 2,7-dihydroxy-3,6,9-trimethyl-9H-xanthene-1,4,5,8-tetraone (DTXT) was tested by reducing power, superoxide anion (O2-·), 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl radical (·OH) scavenging assays. The medium composition for DTXT production by Acremonium cavaraeanum CA022 in solid-state fermentation was optimized using one-factor-at-a-time method and response surface methodology (RSM). The results showed that the reducing power of DTXT at a concentration of 200 μg/mL was not significantly different from that of rutin, but higher than that of VE and BHT. DTXT could scavenge 67.00% of O2-·, 78.83% of ·OH and 76.53% of DPPH radical. The optimal medium formulation was obtained as follows: glucose 0.773%, sodium nitrate 0.185%, H3BO3 0.032%, and VB1 100 μg/100 g. It gave a DTXT yield of 4 150.80 mg/kg, which increased by 1.45 times compared with that before optimization (2 864.83 mg/kg).

In order to understand the dynamic changes of complex lipid contents in human milk during infancy, sequential window acquisition of all theoretical mass spectra (SWATH) with high acquisition hit rate assisted ultra-high performance liquid chromatography-triple quadrupole time of flight tandem mass spectrometry (UPLC-Triple-TOF-MS/MS) was used to identify and quantitatively analyze lipids in human milk at different lactation stages. The results showed that a total of 229 lipids were detected in human milk at the three lactation stages. According to the “Lipid Metabolism and Pathways Strategy”, five classes of lipids were identified: 1) glycerolipids (GLs) mainly including 24 diglycerides and 28 triglycerides; 2) glycerophospholipids (GPs) including 33 phosphatidylethanolamines, 21 phosphatidylcholines, 8 phosphatidylserines, 13 phosphatidylglycerols, 10 phosphatidic acids and 7 phosphatidylinositols; 3) 22 sphingolipids (SP); 4) 10 sterol lipids (ST); and 5) 4 fatty acids (FAs) and their derivatives. The relative contents of GL and SP increased gradually with lactation time, while the relative contents of GP, ST and FAs decreased gradually. This study achieved a comprehensive qualitative and relative quantitative analysis of lipids in human milk. The developed method is sensitive, precise and stable. It provides a basis for the development of infant food simulating human milk at different stages of lactation.

In order to select the optimal near infrared wavelengths for the determination of wheat flour protein, a novel attenuation elimination-binary dragonfly algorithm (AE-BDA) was proposed based on a combination and modification of single-binary dragonfly algorithm (single-BDA) with exponential and linear attenuation functions. Single-BDA and AE-BDA were separately employed to select the characteristic wavelengths for proteins from the near infrared spectra of 160 wheat flour samples. A quantitative prediction model for wheat flour protein content was established by partial least square regression (PLSR) and used to evaluate the results of wavelength selection. The results indicated that compared with single-BDA, fewer but more stable wavelengths were selected using AE-BDA and the established model had better prediction performance with a determination coefficient of 0.972 7 and a root mean square error of prediction (RMSEP) of 0.281 1. The average number of characteristic wavelengths selected from 8 experiments using AE-BDA was 15.8, accounting for 12.6% of the original wavelengths, of which 3 wavelengths were selected in each experiment. According to the analysis of the near-infrared spectra, the selected wavelengths were contained in the major absorption bands of wheat flour proteins and background components. In conclusion, AE-BDA can select the few characteristic wavelengths from near-infrared spectra of wheat flour with high computational efficiency, giving a predictive model with higher accuracy and stability. The proposed method can provide a simpler and more effective wavelength optimization strategy for near-infrared modelling.

In this study, the volatile flavor compounds in Stropharia rugoso-annulate were qualitatively and quantitatively analyzed by headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). The volatile odor profiles of S. rugoso-annulata roasted at different temperatures (0, 100, 120, 140, 160 and 180 ℃) were distinguished using an electronic nose. The aroma characteristics of roasted S. rugoso-annulate were determined by sensory evaluation. The results showed that a total of 87 volatile compounds were identified, including 13 aldehydes, 17 esters, 18 alcohols, 4 alkanes, 9 ketones, 8 acids, 4 pyrazines and 14 other compounds. A total of 25 volatile compounds like isovaleraldehyde and gamma-valerolactone were shared by the six samples. After roasting, the total contents of aldehydes, alkanes and pyrazines were increased, and the fruity, rose-like and cocoa-like aromas were enhanced, while the total content of alcohols was decreased significantly. From the perspective of overall odor perception, the electronic nose could effectively distinguish the volatile flavor profiles of S. rugoso-annulata roasted at different temperatures. Totally 34 key flavor compounds were identified according to their relative odor activity (ROV) values. Among them, isovaleraldehyde contributed the most to the flavor, being responsible for the malty and fruity aromas. The largest number (63) of flavor substances was found in S. rugoso-annulata roasted at 140 ℃. Roasting at 140 ℃ improved the richness of flavor, increased the malty, rose-like, nut-like and cocoa-like aromas, and improved the overall flavor of S. rugoso-annulata. The sensory evaluation showed that roasting enhanced the volatile flavor of S. rugoso-annulata, which was consistent with the above results.

Objective: This study aimed to explore the formation mechanism and composition of unpleasant odorants in fermented walnut yogurt in order to improve its flavor quality. Methods: Comparative experiments and sensory evaluation were used to analyze the effects of different starter cultures and raw materials on the formation of the off-flavor of fermented milk, and the changes in the characteristic odor value of fermented walnut milk as well as acidity, organic acid, protein and fat contents, carbonyl value and the profile of volatile compounds were investigated during walnut milk fermentation, together with the correlation between them. The composition of volatile compounds in walnut yogurt was analyzed by headspace solid phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS), and the key flavor compounds and unpleasant odorants were analyzed by calculating their relative odor activity values (ROAV) as well as using principal component analysis (PCA). Results: The fat content and the carbonyl value were both significantly related to the formation of off-odorants. The major volatile flavor compounds of walnut yogurt included three acids such as caproic acid, three ketones such as acetoin, seven alcohols such as n-hexanol, four aldehydes such as (E)-2-heptenal, butyl butyrate and other compounds. The major volatile compounds with ROAV greater than 1 included (E)-2-heptenal, acetoin, caproic acid, n-hexanol, n-octanol, 1-heptanol, benzaldehyde, 2-nonanone, 2-heptanone, styrene and phenethyl alcohol, and the key flavor compounds were acetoin, caproic acid, (E)-2-heptenal, and n-hexanol. Conclusion: Caproic acid, (E)-2-heptenal, n-hexanol, and benzaldehyde are the major unpleasant odorants of walnut yogurt, and they are mainly formed through lipoxygenase-catalyzed oxidative decomposition of large amounts of linoleic acid and linolenic acid derived from fat hydrolysis during the fermentation process, yielding C6–C9 alcohols, aldehydes, and acids.

Objective: This study compared the differences in the functional components of the root head, taproot, and tail root of Codonopsis pilosula. Methods: The ethanol extracts of each of the three parts were fingerprinted by high performance liquid chromatography (HPLC) and analyzed for lobetyolin content. Moreover, the sugar content was determined by the phenol sulfuric acid method, and the amino acid composition was determined using an amino acid analyzer. Results: The fingerprints of the ethanol extracts from C. pilosula showed a similarity greater than 0.90. A total of 24 chromatographic peaks common to these fingerprints were matched, indicating that the characteristic components of the ethanol extracts were similar. The mean water extract contents in the root head, taproot, and tail root of C. pilosula were 46.05%, 70.26%, and 73.01%, respectively. The mean ethanol extract contents were 48.64%, 72.71%, and 76.71%, respectively. The mean lobetyolin contents were 0.12%, 0.06%, and 0.06%, respectively. The mean total sugar contents were 25.71%, 36.39%, and 39.06%, respectively. The mean polysaccharide contents were 11.83%, 15.74%, and 16.55%, respectively. The mean oligosaccharide contents were 7.85%, 13.39%, and 14.59%, respectively. The mean contents of total amino acids were 8.456 7, 4.285 5, and 4.353 9 mg/g, respectively. The mean contents of fat-soluble substances were 0.20%, 0.15%, and 0.15%, respectively. Conclusion: The functional factors of the taproot and tail root of C. pilosula were similar, and the contents of alcohol extract, water extract, lobetyolin, total sugar, polysaccharide, oligosaccharide, amino acid, and fat-soluble substances were almost the same between the two parts. The contents of lobetyolin, amino acids and fat-soluble substances in the root head were higher than those in the taproot and tail root, whereas the opposite was true for the contents of alcohol extract, water extract, and carbohydrate. The results showed that the medicinal and nutritional components of the taproot and tail root of C. pilosula were similar, indicating that they had similar medicinal and food values. The root head, which is discarded as a waste, contained high levels of medicinal components such as lobetyolin and nutrient components such as amino acids, indicating that it had medicinal and food values.

The present study was conducted to investigate lipid and fatty acid compositions, differential lipids, potential biomarkers and metabolic pathways in the muscles of two indigenous donkey breeds in Dezhou, Shandong, Sanfen (SF) and Wutou (WT), using liquid chromatography-mass spectrometry (LC-MS)-based lipidomics. The results showed that a total of 1 101 lipid molecules belonging to 13 subclasses were identified in both donkey breeds. Triglycerides were the dominant lipids in donkey muscle, followed by phospholipids. The relative content of diacylglycerol in SF muscle was significantly higher than that in WT muscle (P < 0.05), while no significant difference in fatty acid composition was found between SF and WT muscle (P > 0.05). A total of 37 differential lipid molecules were identified (variable importance in the projection above 1, P < 0.05), of which 32 were up-regulated and five were down-regulated in SF muscle compared with WT muscle. Among them, 11 lipid molecules were considered as potential lipid markers to distinguish SF and WT from receiver operating characteristic curve analysis. These differential lipids were involved in glycerophospholipid metabolism, glycosylphosphatidylinositol-anchor biosynthesis, linoleic acid metabolism, alpha-linolenic acid metabolism, and arachidonic acid metabolism. This study analyzed the lipid differences of Dezhou donkey in different breeds at the level of lipid molecules and metabolism, screening of potential biomarkers.

To investigate the impact of the assimilable nitrogenous compound ammonium phosphate on the quality of fermented kiwifruit wine, 100-400 mg/L ammonium phosphate (DAP) was supplemented to kiwifruit juice prior to fermentation. The resultant wine was analyzed for basic physicochemical parameters, potentially harmful alcohols, nutritional components and volatile compounds. Results showed that the addition of 100–400 mg/L of DAP not only stimulated alcohol fermentation during the first 48 hours of fermentation, but also significantly reduced the concentrations of potentially harmful alcohols, such as higher alcohols and methanol in the kiwifruit wine. In particular, supplementation of 300 mg/L of DAP led to a reduction in total higher alcohol and methanol concentrations by 42.84% and 20.1%, respectively. Although DAP supplementation reduced the total amino acid content, it did not have any significant impact on the contents of VC or total phenols in the kiwifruit wine. Nonetheless, the addition of DAP significantly increased the contents of acetate esters and ethyl esters in kiwifruit wine. Particularly, supplementation of 300 mg/L of DAP remarkably increased the concentrations of ethyl acetate, ethyl n-hexanoate, n-octanal, heptanol, and 1-octene-3-ol, enhancing the fruity and floral aromas of kiwifruit wine. Therefore, the addition of an appropriate amount of ammonium phosphate can improve the quality of fermented kiwifruit wine.

The key flavor compounds of Xiaoqu mild-flavor baijiu were qualitatively and quantitatively analyzed by gas chromatography-mass spectrometry-olfactometry (GC-MS-O) and headspace solid phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS). The differences in key flavor compounds between two quality grades of Xiaoqu mild-flavor baijiu were analyzed by multivariate statistics. The results showed that the two quality grades of Xiaoqu mild-flavor baijiu were similar in terms of volatile aroma composition. The contribution of ethyl esters to the flavor of the superior grade was greater than to that of the first grade, while the opposite was observed for some higher alcohols, sulfides, aldehydes and ketones. Partial least squares-discriminant analysis showed that significant differences in the contents of ethyl acetate, ethyl lactate, isobutanol, isoamylol and acetaldehyde existed between the two quality grades of Xiaoqu mild-flavor baijiu, which might be the key factor causing the differences in sensory evaluation and flavor characteristics between them.

In this study, the correlation between different varieties of rapeseed and the flavor of fragrant rapeseed oil was established by analyzing the chemical components of eight rapeseed samples from different varieties and the 22 key flavor compounds and six sensory attributes of the resultant oils. It was found that the content of glucosinolate in rapeseed was correlated with the contents of glucosinolate degradation products (mainly 1-butene, and 4-isothiocyanato-, benzenepropanenitrile) and sulfur compounds (such as dimethyl trisulfide) in fragrant rapeseed oil, which make a positive contribution to the irritating and pickle-like flavor properties. In addition, the contents of protein and carbohydrate in rapeseed affected the contents of heterocyclic compounds (mainly 2,5-dimethylpyrazine, 2,3,5-trimethylpyrazine and 2-ethyl-6-methylpyrazine) in fragrant rapeseed oil, which make a positive contribution to the roasted and burnt flavor characteristics.

To investigate the level of Escherichia coli contamination in frozen foods in Shaanxi province, China, and analyze the potential food safety issues caused by it, a total of 360 frozen food samples (120 frozen dumpling samples and 240 ice cream samples) were collected from four cities (Baoji, Xianyang, Xi’an and Weinan) in Shaanxi province. E. coli strains were isolated and identified by selective culture and polymerase chain reaction (PCR). The 21 virulence genes, 23 antibiotic resistance genes, resistance to 15 common antibiotics and phylogenetic groups of the isolates were investigated. Total 13.6% (49/360) of the 360 samples were contaminated with E. coli, of which five samples (10.2%, 5/49) had coliform counts > 100 CFU/g. Nine virulence genes were detected, among which the detection rate of the extraintestinal pathogenic E. coli-related genes FyuA and iss was the highest (14.3%, 7/49 each). The results of drug susceptibility test showed that the isolates were most commonly resistant to β-lactams and folate metabolism inhibitors (98.0%, 48/49 each), followed by tetracyclines (20.4%, 10/49). The major coding gene of β-lactams was blaCTX and the major coding gene of tetracyclines was tetA. This study also identified one isolate carrying the polymyxin resistance gene mcr-9. Moreover, 20.4% of the strains were multi-drug resistant, and one of them was resistant to up to 13 antibiotics. Four phylogenetic groups (A, B1, C, and F) were detected in all isolates, and group A was the dominant one. The results indicate that there is a risk of the contamination of pathogenic E. coli and multidrug-resistant strains in frozen foods and their transmission to humans through the food chain in Shaanxi, China.

This study aimed to develop a rapid and sensitive method for the quantitation of Vibrio parahemolyticus in seafoods by combining the CRISPR/Cas12a system with saltatory rolling circle amplification (SRCA-Cas12a). The target DNA of V. parahaemolyticus was amplified by SRCA and recognized by the CRISPR/Cas12a system and the single-stranded reporter probe was cleaved by the CRISPR/Cas12a system. The sensitivity, specificity and spiked recovery of SRCA-Cas12a were tested. The results indicated that SRCA-Cas12a could distinguish V. parahaemolyticus from other food-borne pathogens with excellent specificity. Under optimal conditions, a linear relationship between the logarithm of the concentration of V. parahaemolyticus and the intensity of fluorescence signal was established, which was fitted as follows: y = 1.847 2x + 2.473 8 (R2 = 0.986 6) and the detection limit was 3.6 CFU/mL (RSN = 3). The spiked recoveries of V. parahaemolyticus in artificially contaminated samples were 95.5%–104.4%. The method was applied for the detection of actual samples with a sensitivity of 100.0%, a specificity of 95.2%, and a coincidence rate of 97.2%. Hence, this developed method has the advantages of excellent specificity and low detection limit, thereby providing a new strategy for rapid quantitative detection of V. parahaemolyticus.

This work develops a Raman spectral classification method using convolutional neural network (CNN-Raman) for detecting milk powder adulterants. Using a Raman hyperspectral imaging platform, the raw spectra of sufficient milk powder samples were collected and preprocessed by discrete wavelet transform (DWT). Subsequently, the DWT-filtered spectra were used as the input of CNN to construct a multivariate model. The classification results before and after spectral preprocessing were investigated. Unexpectedly, inappropriate spectral preprocessing worsened the classification performance of the CNN model, while the raw Raman spectra were accurately identified by the CNN. The CNN model based on the raw Raman spectra was capable of identifying an unknown sample accurately with a recognition rate of 95.5%. These results reveal that CNN can be combined with spectral preprocessing and modeling to greatly simplify the calculation process of Raman spectral classification. The CNN-Raman method represents a promising tool for quality and safety inspection of milk powder samples.

To investigate the key links of Staphylococcus aureus pollution in the broiler slaughtering process and the molecular characteristics and antimicrobial susceptibility of S. aureus isolates, we collected microbial samples from different production stages (anal swabs from live chicken, soaking, pre-cooling, segmentation, and storage) in a broiler slaughterhouse in Shaanxi Province four times. S. aureus isolates were isolated and identified by selective culture and polymerase chain reaction (PCR) amplification of the nuc gene. Twenty-three virulence genes, 27 drug resistance genes, resistance to 16 common antibiotics, staphylococcal protein A (SPA), multi-locus sequence typing (MLST), and enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR) typing of the isolates were investigated. The results showed that 32 of the 144 samples collected (22.2%) were contaminated by S. aureus. The S. aureus contamination rate in the defeathering process was the highest (40.0%, 12/30), followed by the segmentation (26.7%, 8/30), pre-cooling (21.9%, 7/32), and storage processes (15.6%, 5/32). S. aureus was not detected in the anal swabs. Sixteen virulence genes were detected. Among them, the pvl, seb, sek, seg, sei, sem, sen, seo, seu, sep, and seq genes were detected frequently. Additionally, 96.9% (31/32) of the isolates carried novel enterotoxin genes. Only four drug resistant genes were detected, including blaZ, tet(K), erm(B), and aac(6′)/aph(2′′). The isolates showed resistance to seven of the 16 antibiotics tested, and were most commonly resistant to trimethoprim/sulfamethoxazole, followed by ampicillin, penicillin, tetracycline, ciprofloxacin, erythromycin, and gentamicin. Five clonal types (ST7-t091, ST5-t010/t002 and ST59-t437/t441) and 4 ERIC-PCR clusters (I1-I4) were detected in all the isolates. The isolates from different stages of the broiler slaughtering process had the same ERIC-PCR map, molecular type, drug-resistance profile, virulence gene profile, and antibiotic resistance gene profile. The results showed that S. aureus contamination was common in broiler slaughtering process. Cross-contamination could be observed among different processing stages, among which scalding was considered to be the key link of contamination. It was also found that the virulence genes carried by the isolates had a significant correlation with the molecular type (P < 0.05). The monitoring of different slaughter steps is helpful to identify the critical control points of S. aureus pollution, which can effectively prevent and control the outbreak of food-borne diseases.

An ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed for the determination of benzoic acid and hippuric acid in meat and offal. Through spiked recovery tests, methanol was selected as the extraction solvent. The extract was purified on a PRiME HLB solid phase extraction (SPE) column, detected in the multi-reaction monitoring (MRM) mode, and quantified by an external standard method. The results showed that good linearity was observed for benzoic acid and hippuric acid within the concentration range of 20–1 000 and 4–200 ng/mL with correlation coefficients of greater than 0.99, and the detection limits 12.5 and 2.5 μg/kg, respectively. The limits of quantification for benzoic acid and hippuric acid were 50 and 10 μg/kg, respectively; the recoveries at three spiked concentration levels were between 70.5% and 99.7%, and the relative standard deviations (RSDs) of precision were 0.3%–7.1% (n = 6). The proposed method had good repeatability and intra- and inter-day stability, with RSDs equal to or less than 7.2%. Therefore, this method is simple, accurate and sensitive, and has a good recovery rate. It can provide technical support for the supervision of benzoic acid and hippuric acid residues in meat and offal.

The Raman spectra of apple skin tissue at different stages of infection by spoilage fungi were collected, and the Raman peaks were analyzed by comparing them with the Raman spectra of authentic standards. The characteristic spectral peaks of cellulose, pectin and polysaccharide were selected to construct pseudo color images showing the distribution of these three components in the cell wall and intercellular space of apples, and principal component analysis (PCA) combined with linear discriminant analysis (LDA) was used to establish a discriminant model for determining different stages of infection of five dominant spoilage fungi in apple tissue. It was found that apples had response peaks at 1 645 and 2 946 cm-1, which were assigned to cellulose, pectin and lignin. The pseudo color images showed that these components were unevenly distributed in the cell wall and intercellular space of apples. With the aggravation of the infection degree of spoilage fungi, the intensity of the characteristic Raman peaks showed a downward trend. PCA showed that the Raman spectra of apples at different stages of infection by spoilage fungi had clustering trend, and the recognition accuracy of the discriminant model for the calibration set and prediction set was more than 95%. The above results show that Raman chemical imaging can effectively characterize the infection process of apples by spoilage fungi.

The accumulation characteristics, tissue distribution and elimination pattern of atrazine in Crassostrea gigas were studied by the semi-static water contact poisoning method after being exposed to seawater containing different atrazine concentrations of 10 and 100 μg/L. The results showed that for each exposure concentration, the content of atrazine in each tissue of C. gigas reached equilibrium between days three and seven days after being switched to clean seawater. Moreover, the half-life time of atrazine in C. gigas were 0.20–0.32 days with a bioconcentration factor (BCF) ranging from 1.68 to 3.46 mL/g. The gill and visceral mass were the major target tissues for the accumulation of atrazine, and the content of atrazine in the adductor muscle was the lowest. The elimination capacity of C. gigas for atrazine increased with increasing exposure concentration. Meanwhile, the content of atrazine in each tissue decreased exponentially with depuration time. The elimination rate of atrazine was 90.1%–97.1% after depuration for one day, and atrazine might be metabolized through the gill.

A method was developed for the simultaneous detection of 46 foodborne stimulant drug residues in animal-derived foods by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The samples were enzymatically digested for 16 h at 37 ℃, extracted with acetonitrile, defatted with n-hexane saturated with acetonitrile, purified by dispersive solid phase extraction (DSPE) with octadecylsilane bonded silica (C18) and neutral alumina as adsorbents, and finally separated on a Waters ACQUITY BEH C18 column by gradient elution using a mixture of 0.005% formic acid and methanol as the mobile phase. The detection was operated using an electrospray ionization mass spectrometer in both the positive and negative ion modes, and quantitation was performed by the external standard method. The results showed that good linear relationships were obtained for all the analytes in the investigated concentration ranges with correlation coefficients more than 0.998. The limits of detection (LODs) were 0.05–1.0 μg/kg, and the limits of quantitation (LOQs) were 0.1–2.0 μg/kg. Average recoveries of the analytes in pork ranged from 76.0% to 111.9%, with relative standard deviations (RSDs) of 2.3%–12.4%. The developed method is simple, rapid and practical, and can provide effective technical support for the detection of foodborne stimulant drug residues.

A molecularly imprinted photonic hydrogel (MIPH)-based sensor which combines molecular imprinting with photonic crystal technology was constructed and used for the detection of dibutyl phthalate (DBP) in alcoholic beverages. Under optimal conditions, the response time of the MIPH sensor for DBP was 3 min, the diffraction peak displacement of MIPHs showed a good linear relationship with DBP concentration ranging from 0.01 to 0.1 mg/L (R2 = 0.992 0), and the detection limit of DBP was 0.01 mg/L (RSN = 3). The sensor was used to detect DBP in baijiu samples, revealing that the spiked recoveries of DBP were 95.60%–103.20%. Experimental results showed that the sensor has the advantages of simple operation, fast response, high selectivity and low cost, and has a broad application prospect in the safe and rapid screening and detection of harmful substances in alcoholic beverages.

The study aimed to investigate the status of heavy metal pollution of offshore fish and the health risk of heavy metals through consumption of offshore fish. The concentrations of plumbum (Pb), cadmium (Cd), chromium (Cr), total arsenic (As), inorganic As and total mercury (Hg) were determined in 6 tissues (head, tail, skin, bones, flesh and viscera) from 9 offshore fish species such as Decapterus macrosoma and Scomberomorus niphonius using inductively coupled plasma mass spectrometry (ICP-MS), liquid chromatography-atomic fluorescence spectrometry (LC-AFS) and atomic fluorescence spectrometry (AFS). The heavy metal pollution status of the 9 offshore fish species was estimated by calculating the pollution index and the target hazard coefficient index. The results showed that in 9 (16.67%) of the 54 groups of fish tissue samples, Cr levels exceeded the national standard limit (GB 2762-2017). In 7 (12.96%) of these groups, Cd levels exceeded the national standard limit. In 2 (3.70%) of these groups, Pb levels exceeded the national standard limit. In all groups, the concentrations of inorganic As and total Hg were lower than the national standard limits. For 7 (12.96%) of the 54 groups, heavy metal levels in fish viscera exceeded the national standard limit. For 3 (5.56%) of these groups, heavy metal levels in fish head and tail exceeded the national standard limit. Heavy metal levels in fish flesh did not exceed the standard limit for any of the groups. The single factor pollution index showed that the most serious pollution status occurred in Cr, followed in sequence by Cd and Pb, and the pollution levels of inorganic As and total Hg were the lowest. The highest comprehensive pollution index (3.877) was seen for the viscera of Sardina pilchardus suggesting a serious pollution level. The comprehensive pollution index for the viscera of D. macrosoma, S. niphonius, Pneumatophorus japonicus and Nemipterus virgatus was at the medium pollution level. The health risk indexes of single and multiple heavy metals in fish flesh from the 9 species were all less than 1, indicating that the heavy metal pollution in the viscera of offshore fish is more serious, but the fish flesh can be consumed safely. The results of this study will guide daily consumption of offshore fish and comprehensive development of by-products.