Objective To compare the taste characteristics, physical and chemical indicators of preserved mustards samples in market, and statistically analyze the correlation between taste quality and physical and chemical indicators. Methods The 22 samples of preserved mustards from Zhejiang, Sichuan and Hunan were collected, and the taste characteristics of preserved mustards were analyzed by artificial sensory evaluation and electronic tongue, the physical and chemical indicators such as moisture content, total acid, amino acid nitrogen, trichloroacetic acid (TCA) soluble peptides, nitrite, and reducing sugar content were analyzed. Results The saltiness and umami of preserved mustards were prominent, and the acidity intensity of different preserved mustards varied greatly. Umami was significantly negatively correlated with sourness and saltiness (P<0.01), and significantly negatively correlated with bitter aftertaste (P<0.05). Water content had a great influence on the taste quality of preserved mustards, and was significantly positively correlated with the taste (P<0.05). The salt content was significantly negatively correlated with the total acid content (P<0.01). Conclusion The taste characteristics and physical and chemical indexes of different preserved mustards samples are very different, and some preserved mustards have high salt content, so it is necessary to establish quality standards; the taste quality and physical and chemical indexes of preserved mustards from different origins does not show obvious regional characteristics; there is a negative correlation between the indexes of carbohydrate fermentation products and protein fermentation products in preserved mustards.

Objective To isolate a strain of Listeria monocytogenes from frozen chicken meat sold in Gansu Province and analyze its serotype, antibiotic resistance phenotype, and genomic characteristics. Methods The slide agglutination method was used for serological identification, the broth microdilution method was used to analyze the sensitivity of the strain to 8 kinds of antibiotics, and the genomic characteristics were analyzed by sequencing. Results The strain was identified as Listeria monocytogenes by 16S rDNA species identification, with a 1/2a serotype, phylogenetic lineage II, subline SL 155, and clone CC 155 MLST 705, cgMLST 13240. Sensitive to 4 kinds of antibiotics including ampicillin, penicillin, vancomycin, and meropenem, and multidrug-resistant to 4 kinds of antibiotics including erythromycin, ciprofloxacin, tetracycline, and compound sulfamethoxazole. Simultaneously carrying aph(3')-III, ant(6)-Ia, dfrG, fosX, lnu(B), lsa(E), erm(B), tet(S) and tet(M) 9 kinds of resistance genes, carrying 5 virulence genes of LIPI-1, prfA gene deletion, carrying 12 kinds of internalization genes, no premature stop codon of inlA gene carrying, no LIPI-3, and LIPI-4. Conclusions The Listeria monocytogenes carries abundant virulence genes and resistance genes, and its resistance phenotype is basically consistent with the resistance genes, showing multiple drug resistance, providing a reference for the prevention and treatment of listeriosis.

Objective To optimize the extraction process of Chaenomeles sinensis polyphenols and study their antioxidant activity. Methods The extraction process of Chaenomeles sinensis polyphenols was optimized through single factor and orthogonal experiments; the in vitro experiments were simultaneously conducted to investigate the total reducing ability, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability, and hydroxyl radical scavenging ability of Chaenomeles sinensis polyphenols. Results The optimal process for extracting polyphenols from Chaenomeles sinensis was: Ethanol volume fraction of 60%, solid-liquid ratio of 1:25 (g/mL), ultrasonic temperature of 55 ℃ and ultrasonic time of 90 min. Under these conditions, the polyphenol extraction amount was 2.22 mg/g; at a sample concentration of 1.0 mg/mL, the total reducing ability, DPPH radical scavenging rate and hydroxyl radical scavenging rate of Chaenomeles sinensis polyphenols were determined to be 2.41±0.02, 89.33%±0.24%, and 81.30%±1.27%, respectively, all higher than vitamin C at the same concentration (2.29±0.08, 86.05%±0.39%, 80.94%±0.41%), indicating that Chaenomeles sinensis polyphenols had good antioxidant activity and promising application prospects. Conclusion This study provides a reference for further research and application of polyphenols in Chaenomeles sinensis, offers new ideas for the diversified and high-value utilization of Chaenomeles sinensis resources, and provides theoretical basis for the deep processing of Chaenomeles sinensis resources and rational dietary selection.

Objective To elucidate the effects of flower of Changshan-huyou on the aroma profile of black tea. Methods This study employed solid phase microextraction-gas chromatography-tandem mass spectrometry (SPME-GC-MS) to differentially analyze the aroma components of flower of Changshan-huyou, Jiukeng black tea, and the derived Changshan-huyou scented tea. Results A total of 186 volatile compounds were identified in this paper, with 92, 78 and 67 kinds of volatile compounds detected in flower of Changshan-huyou, Jiukeng black tea and Changshan-huyou scented tea, respectively. The volatile composition of flower of Changshan-huyou was mainly characterised by alcohols and alkenes, whereas the volatile profiles of Jiukeng black tea and Changshan-huyou scented tea were mainly alcohol-rich. Nerolidol and linalool were found to be the predominant aroma components in Changshan-huyou scented tea, imparting a pronounced flora, fruity aroma and sweetness. Comparative analysis revealed an increase in alcohols and a concomitant decrease in alkenes in Changshan-huyou scented tea compared to flower of Changshan-huyou. Conversely, an increase in alkenes and a decrease in aldehydes were observed in Changshan-huyou scented tea compared to Jiukeng black tea. In addition, 32 kinds of unique compounds were identified in Changshan-huyou scented tea, which may be due to its unique processing techniques and the specific varieties of raw materials used. Conclusion The results of this research not only substantiate the aroma signature of Changshan-huyou scented tea, but also provide insights into its quality enhancement, paving the way for standardised production and innovative development strategies.

Objective To understand the residual levels of chlorpyrifos in vegetables and fruits in Shanghai in 2014—2023, and evaluate the dietary exposure risk of chlorpyrifos in vegetables and fruits. Methods A number of different varieties of vegetables and fruits in Shanghai were inspected and monitored for the detection of chlorpyrifos from 2014 to 2023. Combined with the food consumption data of residents in Shanghai in 2013, dietary exposure risk assessment of chlorpyrifos were conducted by point assessment method. The assessment results were compared with the acute reference dose (ARfD) and acceptable daily intake (ADI) to assess the acute and chronic exposure risk of chlorpyrifos in vegetables and fruits in residents in Shanghai. Results The quantity of vegetables samples was 33796, the detection rate was 0.97%, the average value was 0.00131 mg/kg, and the exceedance rate was 0.46%. The quantity of fruits samples was 9228, the detection rate was 5.26%, the average value was 0.00320 mg/kg, and the exceedance rate was 0.00%. The acute exposure of chlorpyrifos residues ingested through vegetables and fruits were 0.0432 mg/kg bw and 0.0141 mg/kg bw, the ratio of acute exposure to ARfD respectively were 43.19% and 14.15% among the population aged 3 and above. The chronic exposure of chlorpyrifos residues ingested through vegetables and fruits were 5.34×10^-6 mg/kg bw and 8.43×10^-6 mg/kg bw, the ratio of chronic exposure to ADI respectively were 0.053% and 0.084%. Conclusion Both the acute and chronic exposure risks of chlorpyrifos ingested through vegetables and fruits in residents are low in Shanghai.

Objective To investigate the contamination status and conduct a risk assessment of foodborne pathogens in food samples from Baotou City, Inner Mongolia, from 2016 to 2023. Methods According to the requirements of the Inner mongolia autonomous region food safety risk monitoring plan—Microbiological monitoring, food samples were collected from 10 counties and districts in Baotou City between 2016 and 2023. Detection of foodborne pathogens was performed following standard operating procedures. Results Over the 8-year period, a total of 1358 food samples from 17 major categories were collected, and 485 strains of pathogenic microorganisms belonging to 14 species were detected, with an overall detection rate of 26.58% (361/1358). Among the 11 categories of food samples with detected pathogens, meat and meat products, as well as aquatic products and their products, showed higher detection rates of 42.35% (227/536) and 47.78% (43/90), respectively. Food samples from sampling points such as farmers' markets and farming sites were heavily contaminated, with detection rates of 42.13% (75/178) and 61.22% (30/49), respectively. Among the pathogens, Vibrio alginolyticus and Campylobacter had higher detection rates of 40.00% (8/20) and 50.22% (113/225), respectively. The positive detection rate of monitored samples increased annually, rising from 1.05% (2/190) in 2016 to 50.00% (100/200) in 2023. Conclusion The contamination level of foodborne pathogens in meat and meat products, as well as aquatic products and their products, is relatively high in Baotou City. Sampling points such as farmers' markets pose a risk of causing foodborne diseases.

Objective To compare the mold counting effects of potato dextrose agar and rose Bengal agar as 2 types of counting culture medium. Methods Growth rate, specificity, and selectivity were compared between potato dextrose agar and rose Bengal agar culture medium using 20 kinds of standard mold strains and 15 kinds of common foodborne pathogen strains. Additionally, the counting effects of both culture medium were assessed using 36 actual food samples and 174 swab samples from food contact environments in refrigerators. Results The growth rate (PR value) of the 20 kinds of mold strains on both potato dextrose agar and rose Bengal agar culture medium was greater than 0.7, and the selectivity (G value) was less than 1. However, molds on potato dextrose agar culture medium exhibited more typical colony morphology, indicating better specificity than rose Bengal agar culture medium. In the detection of actual samples, the detection rate of potato dextrose agar culture medium was relatively high, showing a significant difference compared to rose Bengal agar culture medium (χ²=13.551, P=0.001). It exhibited a particularly higher detection rate in samples with low contamination (χ²=9.929, P=0.001). However, for highly contaminated samples, rose Bengal agar culture medium was more convenient for counting. Conclusion Using a single culture medium can affect counting results. It is recommended to apply 2 types of culture medium or select an appropriate counting medium based on the contamination level when conducting mold counting tests on food samples.

Objective To establish an analytical method for the determination of 146 kinds of pesticide residues in animal derived foods by enhanced matrix removal-lipid dispersion solid phase extraction (dSPE EMR-Lipid) and purification technology coupled with gas chromatography-tandem mass spectrometry (GC-MS/MS). Methods The 5 g sample were added to 2 mL ultrapure water, extracted with acetonitrile, freezed for 10 min, separated with QuEChERS EN-extraction package, cleaned-up with dSPE EMR-Lipid, then was detected by GC-MS/MS in dynamic multi-reaction monitoring (DMRM) mode. The analytes were quantified by matrix-matched standard curve method. Results The results showed that 146 kinds of pesticides had good linearities in the concentration of 5-320 μg/L, the linear correlation coefficient of the compounds were greater than 0.9939, and the limits of detection of the method were 0.04-10.91 μg/kg, the limits of quantification were 0.11-32.72 μg/kg. The average recoveries of 146 kinds of pesticides at the spiked level of 0.01, 0.02 and 0.10 mg/kg ranged from 61.3% to 119.3%, relative standard deviations were 0.15%-16.02%. Conclusion The method is simple in pre-treatment, convenient in operation, rapid, sensitive and accurate in detection, can meet the simultaneous detection requirements for multiple pesticide residues. It is suitable for preliminary screening and quantitative detection of multiple pesticide residues in animal derived food.

Objective To investigate the prevalence, virulence phenotypes, and drug resistance phenotype of Vibrio parahaemolyticus in freshwater food, seafood, and ready-to-eat food in Yangzhou. Methods Freshwater food, seafood and ready-to-eat food samples were collected from 9 sampling points in Yangzhou markets for isolation and identification of Vibrio parahaemolyticus. The motility, hemolytic activity, and drug resistance phenotype of the isolates were analyzed. Results In 2023, a total of 289 samples were collected in the Yangzhou market, from which 63 strains of Vibrio parahaemolyticus were isolated, with an isolation rate of 21.80%. Among them, the isolation rate of freshwater food was 45.35% (39/86), seafood 28.75% (23/80), and ready-to-eat samples 0.81% (1/123), indicating a higher isolation rate in freshwater food compared to seafood in the markets of Yangzhou. The proportion of highly motility strains in freshwater food isolates was 30.77%, higher than that of the seafood isolates (17.39%). However, the proportion of strains with high hemolytic activity was 53.85% in freshwater food isolates, slightly lower than the 60.87% in seafood isolates. Antibiotic resistance profiling showed that all Vibrio parahaemolyticus isolates were resistant to ampicillin and cefazolin, while they were resistant to ceftazidime, tetracycline, ciprofloxacin, chloramphenicol, amikacin, meropenem and gentamicin. Conclusion This study highlights a high detection rate of Vibrio parahaemolyticus in Yangzhou markets and reveals differences in virulence and antibiotic resistance among isolates from different sources, offering valuable insights for monitoring and controlling the pathogen.

Objective To optimize the fermentation condition of Enterococcus faecium with the capability of high-yield biogenic amine production by response surface design. Methods Based on the previous single factor experiment results, response surface methodology was used to investigate the interaction among 3 factors with different levels, namely culture temperature (10, 15, 20 ℃), initial pH (5.0, 5.5, 6.0), and sodium chloride addition (4.5%, 5.5%, 6.5%), on the production of biogenic amines by Enterococcus faecium. The fermentation condition for controlling the production of tyramine and phenethylamine by Enterococcus faecium were optimized. Results The results showed that the regression equations for the production of tyramine and phenethylamine at 48 h were obtained with R²=0.9866, adjusted R²=0.9693 for tyramine and R²=0.9875, adjusted R²=0.9714 for phenethylamine, the order of affecting the production of casein and phenethylamine was culture temperature>NaCl addition>initial pH.. The optimal fermentation condition to control the tyramine production of Enterococcus faecium was initial pH of 6.0, incubation temperature of 10.9 ℃, and NaCl addition level of 4.5%. The optimal fermentation condition to control the phenylethylamine production was initial pH of 5.34, incubation temperature of 13.8 ℃, NaCl addition level of 5.8%. Conclusion The results provide references for the effective control of the biogenic amine production of Enterococcus faecium growing in fermented food such as fermented meat products.