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.

The popularization of the concept of health in the new era has made the public extremely concerned about food safety. As an important factor affecting food safety, multi-pesticide residues have become the focus of attention for dietary consumers. This paper focused on the cumulative dietary exposure risk of multi-pesticide residues and reviewed the research progress in this field at home and abroad, covering aspects such as assessment frameworks, assessment methods, assessment software and databases. Secondly, it discussed and analyzed the differences in the cumulative dietary risk assessment systems of different international organizations and countries as well as the latest research methods at home and abroad, such as the introduction of advanced data analysis technologies and the adoption of multidisciplinary research models, to comprehensively assess the cumulative dietary exposure risk of multi-pesticide residues. Thirdly, it clarified the importance of relevant databases and software in the assessment process and pointed out the difficulties in data grouping, acquisition and standardization in the current risk assessment research. Finally, it putted forward reasonable suggestions in view of the current situation and existing problems of the cumulative dietary risk assessment of multi-pesticide residues, aiming to provide theoretical support for food quality and safety and the green development of pesticides in the new era.

Excessive intake of fat in human body is the main cause of obesity and cardiovascular and cerebrovascular diseases. With the gradual enhancement of national health awareness, people gradually pay attention to fat substitutes with low calorie and low energy. Fat substitutes can not only meet people's sensory needs for color, fragrance and taste of food, but also reduce the intake of fat without changing the taste quality of food, which is of great significance to prevent various chronic diseases. Therefore, producing low-fat or fat-free food is an important way to improve people's eating habits and improve people's health. Fat substitutes are a kind of substances that mimic the fat in natural foods, which can be divided into 3 types: Fat substitutes (esterified derivatives of fatty acids, with almost zero digestibility in human body), fat simulators (carbohydrate fat simulators and protein fat simulators) and compound fat simulators. Fat substitutes can reduce the fat content in food, and more importantly, they can improve the oral sensory lubrication texture of food. This paper summarized the application and development prospect of fat substitutes in modern food research at home and abroad, in order to provide guidance for the research and development of low-calorie diet.

Objective To establish a quantitative analysis of multi-components by single marker (QAMS) method for the simultaneous determination of 9 kinds of components in Andrographis paniculata. Method The relative calibration factors of andrographolide with forsythitin, oleanolic acid, caffeic acid, andrographolide, dehydrated andrographolide, andrographolide, deoxyandrographolide, dehydrated andrographolide half succinate and sodium bisulfite were established by ultra performance liquid chromatographolide-tandem mass spectrometry. The relative correction factor was used to calculate the content of each component, and the calculated results of QAMS method were compared with the measured values of external standard method. Results The relative correction factors showed good reproducibility, and there was no significant difference between the results obtained by the QAMS method and the external standard method. Conclusion The QAMS method is suitable for the simultaneous determination of 9 kinds of components in Andrographis paniculata, ensuring the reliability of quality.

Objective To investigate the extent of lead contamination in commercial foods and assess the health risk from dietary lead intake of the residents in Guangzhou in 2023. Methods In 2023, the 310 samples were collected from 3 food categories in 11 districts of Guangzhou, China. Lead was measured in the samples using inductively coupled plasma mass spectrometry. Dietary exposure to lead was calculated based on the food consumption survey of Guangzhou residents in 2011, and the health risk of the population was evaluated using the margin of exposure (MOE) method. Results Lead was detected in 83.23% of the overall samples, and the over-standard rate was 0%, with an average lead content of 0.040 mg/kg. The highest lead level was found in bivalves, 0.205 mg/kg. The average daily dietary lead exposure of the whole population and all age groups (3-6 years old, 7-17 years old, 18-59 years old, and 60 years old and above) in Guangzhou and the consumers with high dietary exposure of all age groups (95th percentile P₉₅) were: 0.082, 0.120, 0.097, 0.078, 0.081 μg/(kg·d) and 0.225, 0.330, 0.268, 0.206, 0.226 μg/(kg·d). The contribution of rice and rice products, brassica vegetables, and leafy vegetables to dietary lead exposure was relatively significant. The MOE values for lead in residents of all age groups were greater than 1, with the MOE values for minors being lower than those for adults, particularly among high dietary exposure populations. Conclusion In 2023, there is a certain degree of lead contamination in the food items under close watch in the Guangzhou market. The average dietary lead exposure of residents of all age groups is within the acceptable range. However, it is still necessary to pay attention to key food items and take measures to reduce the dietary lead exposure risk for residents in Guangzhou.

Objective To establish a method for the determination of chlorophyll a and chlorophyll b content in vegetables by convergence chromatography (CC). Methods The Soxhlet extraction method was used for efficient extraction of chlorophyll from vegetables and their products, followed by separation and detection using an ultra-performance convergence chromatography system coupled with a ultraviolet-visible detector. Results Through comparison of the stability of different solvents, petroleum ether was selected as the extraction solvent, and the extraction conditions were optimized. The method was validated with a limit of detection of 0.02 mg/kg, a limit of quantification of 0.06 mg/kg, a linear range of 0.06-800.00 mg/kg, a spike recovery rate of 99%-102%, and a relative standard deviation of 2.2%-14.0% for real samples. The reliability and accuracy of the method were confirmed through precision testing of real samples, including kale, fresh mustard greens, pickled mustard greens, dried pickled mustard greens, steamed dried pickled mustard greens, and boiled dried pickled mustard greens, as well as cross-validation with existing standard methods. Conclusion This study establishes a CC-based method for detecting chlorophyll a and chlorophyll b in vegetables, demonstrating high sensitivity, a wide linear range, good specificity, and precision. The method is not only suitable for laboratory research but also has practical application potential.

Objective To establish a method for the simultaneous determination and risk assessment of multi-class pesticide residues in Cucumis sativus L. and Malus pumila Mill. using QuEChERS-liquid chromatography-tandem mass spectrometry. Methods Fruit and vegetable samples were homogenized using acetonitrile as extraction solvent, sodium chloride and anhydrous sodium acetate as salting-out agent, and the supernatant was taken and purified by primary secondary amines (PSA), graphitized carbon black (GCB) and anhydrous magnesium sulfate reagent, and 7 kinds of pesticides were analyzed in 11 min using an Agilent Poroshell 120 EC-C₁₈ column with gradient elution. The potential health risks associated with the consumption of Cucumis sativus L. and Malus pumila Mill. were assessed by calculating the estimated daily intake the estimated dietary intake (EDI) and hazard quotient (HQ). Results The 7 kinds of pesticides exhibited satisfactory linearity within the range of 5‒500 μg/L, with correlation coefficients more than 0.99. The limits of detection were 0.5‒1.0 μg/kg and the limits of quantification were 2.0‒4.0 μg/kg. The average recoveries ranged from 71.0% to 118.8% at three different spiked levels, with the relative standard deviations ranging from 3.1% to 12.7%. Concurrently, the HQ values of individual pesticides evaluated from the acceptable daily intake (ADI) were found to be less than 1, and their risks were within acceptable limits. Conclusion The method exhibits high accuracy, precision, and sensitivity, and is suitable for the simultaneous determination of multi-class pesticide residues in fruit and vegetable samples. Furthermore, the risk assessment results of this study demonstrated that the health risk to individuals from pesticide residues in Cucumis sativus L. and Malus pumila Mill. is within acceptable limits.

Objective To explore the contents of 7 kinds of elements in agricultural products in a certain area in North China plain, including lead (Pb), cadmium (Cd), mercury (Hg), arsenic (As), tin (Sn), nickel (Ni) and chromium (Cr), and evaluate the safety risks of dietary ingestion. Methods The samples were pretreated by microwave digestion, and the contents of 7 kinds of heavy metals in 611 agricultural products collected in the certain area from 2022 to 2024 were determined by inductively coupled plasma mass spectrometry (ICP-MS). Index (P_i), Nemero comprehensive pollutant index (P_N) and target hazard quotient/total target hazard quota (THQ/TTHQ) were used to evaluate the pollution levels of heavy metals in agricultural products. Results All elements except Hg were detected in the agricultural products. Among them, the content of Pb and Cr in individual samples exceeded the limit values specified in GB 2762—2022 National food safety standard-Limits of contaminants in foods (Pb≤0.2 mg/kg, Cr≤0.5 mg/kg). The overall content levels of the 7 kinds of elements were relatively low, and their order in the agricultural products was Ni (0.192 mg/kg)>Cr (0.040 mg/kg)>Pb (0.017 mg/kg)>Sn (0.011 mg/kg)>As (0.009 mg/kg)>Cd (0.005 mg/kg), the heavy metal content of agricultural products in different types and regions was quite different, and the THQ/TTHQ of all agricultural products was less than 1, and the P_i and P_N were less than 1. Conclusion The quality and safety of agricultural products in the study area are in good condition, and the level of heavy metal pollution is relatively low. However, there may be potential heavy metal exposure risks in some individual villages and towns in the southeastern part, and the dietary exposure risks for children are greater than those for adults.

In recent years, mycotoxin contamination in food has become an important food safety issue with global concern. Mycotoxins are a type of secondary metabolites produced by fungi with characteristics of high toxicity, difficult decomposition and chemical stability. It is of great significance to establish an efficient and safe mycotoxin detoxification technology applicable to food. Based onenzyme catalysis, the biological detoxification technology has the advantages of high substrate specificity, mild conditions, green environment, which can overcome the damage of traditional physical and chemical detoxification technology to the quality and nutritional value of food. Immobilized enzyme technology can improve the catalytic performance of enzymes, endow them with values such as stability, reusability, and high throughput, as well as overcome the limitations of biological enzymes in the application process. This article reviewed the application of immobilized enzyme technology in food mycotoxin removal, analyzed the deficiencies of the current immobilized enzyme technology applied in food detoxification and possible future research directions, with a view to providing research ideas for the construction of more efficient immobilized enzyme catalysts.

Objective To analyse the types and content of metabolites in the stems and leaves of Platycodon grandiflorus by ultra performance liquid chromatography-Quadrupole/Orbitrap high-resolution mass spectrometry (UPLC-Q/Orbitrap HRMS). Methods Stems and leaves of two-year-old purple flowered Platycodon grandiflorus from different sources was used as experimental materials. UPLC-Q/Orbitrap HRMS technology was used to analyze the extracts of Platycodon grandiflorus stems and leaves in negative ion mode, using orbitrap for MS1 full scan and data dependent acquisition ion trap for MS2 scan, and screen for differential metabolites of Platycodon grandiflorum stems and leaves from different sources. Results A total of 18 metabolites were detected in the stems and leaves of Platycodon grandiflorum, including 4 flavonoids, 2 alkynyl glycosides, and 12 saponins (1 metabolite that had not been reported). The basic structure of this unknown compound was polygalacic acid-glucose- xylose/arabic glycoside. Through comparative analysis, differences in chemical composition of Platycodon grandiflorus among different sources were discovered. The 6 differential metabolites of Platycodon grandiflorus from China and South Korea and 1 differential metabolite of Platycodon grandiflorus from Yanbian area were screened. Conclusion The comprehensive analysis results indicate that the stems and leaves of Platycodon grandiflorus have rich chemical components, and the stems and leaves of Platycodon grandiflorus from different sources have compound differences, which have high development and utilization prospects, providing theoretical basis for the development and utilization of aboveground resources of Platycodon grandiflorus.