Objective To investigate the characterization of potential pathogen and antibiotic resistance genes (ARGs) from some commercially raw fruit and vegetables in Beijing, 2024, and explore their potential food safety risks. Methods In this study, the characterization and potential risks of ARGs, mobile genetic elements (MGEs) and potential pathogens were described by the combining high-throughput quantitative polymerase chain reaction (HT-qPCR), 16S rRNA amplicon sequencing with bio-informatics and multivariate analysis. Results A total of 182 ARGs subtypes belonging to 9 antibiotic types and 9 MGEs subtypes were detected with the abundance of 6.08×10³-1.57×10⁸ copies/g and 3.77×10⁴-3.50×10⁸ copies/g, respectively. It was seen that the diversity and abundance of ARGs, MGEs and bacterial community in fruits were significantly lower than those in vegetables (P<0.05). Acinetobacter, Leuconostoc, Klebsiella, Stenotrophomonas and Serratia were the main potential pathogens, with Enterobacterales and Acinetobacter johnsonii as signature potential pathogens in solanaceous and leafy vegetables, respectively. MGEs and multiple ARGs were carried by the most of potential pathogens with multiple antibiotic resistance, whose transmission among them were mainly drove by the horizontal gene transfer of MGEs carrying ARGs (57.56%). Conclusion There are various and abundant ARGs and potential pathogens in raw vegetables and fruits in Beijing, 2024, with multiple antibiotic resistance, whose transmission among bacterium are mainly drove by the horizontal gene transfer of MGEs carrying ARGs, which can threaten human health. High attention shall be attached.

Objective To understand the residue status and exposure levels of 6 kinds of quinolone antibiotics in common freshwater fish and shrimp sold in Beijing. Methods The 90 freshwater fish and shrimp products from 40 supermarkets and farmers’ markets in 9 districts and counties of Beijing were randomly sampled for the determination of 6 kinds of quinolone antibiotics in fish and shrimp meat by liquid chromatography-tandem mass spectrometry. The exposure risk of quinolone antibiotic residues in fish and shrimp to residents of 10 gender/age groups was assessed by the index of food safety (IFS). Results The 4 kinds of quinolone antibiotics were detected in 90 fish and shrimp samples. The detection rate for pefloxacin, ofloxacin, enrofloxacin and ciprofloxacin were 1.11% (1/90), 1.11% (1/90), 26.67% (24/90) and 6.67% (6/90). There were excessive samples of pefloxacin, ofloxacin and enrofloxacin detected, with an exceedance rate of 1.11% (1/90), 1.11% (1/90) and 5.56% (5/90) respectively. Norfloxacin and lomefloxacin were not detected in all samples. The IFS of quinolone antibiotics ranged from 0.040-0.067 in the general-case scenario and from 0.170-0.283 in the worst-case scenario, which was much less than 1. Conclusion The detection of quinolone in freshwater fish and shrimp sold in Beijing is dominated by enrofloxacin and ciprofloxacin, and the health risk of 6 kinds of quinolone antibiotics to human beings is at a safe level in this study, which provides regional data support for the assessment of the quality of aquatic products and the revision of food safety standards.

Objective To assess the dietary exposure risk of mycotoxins for Beijing consumers, based on the mycotoxins contamination data during the cold storage period of Castanea mollissima which harvested in Huairou District, Beijing. Methods Castanea mollissima samples were collected from the 4 highest yielding townships in Huairou District. Samples were stored in a cold storage for 1 year and sampled once a month to determine the content of 21 kinds of fungal toxins. Based on the 2002 Beijing residents’ dietary consumption survey data, point estimation method, probability method and cumulative risk assessment modeling method of multiple fungal toxins were used to evaluate the acute and chronic dietary exposure risks of different genders of consumers. Results The estimated daily intake levels of alternariol and alternariol monomethyl ether in some Castanea mollissima samples were higher than 2.5 ng·kg^-1·bw·d^-1. The estimated daily intake levels of tentoxin and tenuzonic acid in all samples during the entire storage period did not exceed 1500 ng·kg^-1·bw·d^-1. The estimated daily intake/tolerable daily intak of nivalenol, fumonisin B₁, total fumonisin and zearalenone were all less than 100. The margin of exposure (MOE) was used to analyze the sterigmatocystin, and the result was greater than 10000. The 2 kinds of different chronic effects were analyzed for ochratoxin A. The cumulative risk assessment of mycotoxins in Castanea mollissima samples showed that some samples had MOE below 100 after storage for about 10 months. Conclusion All varieties of Castanea mollissima samples are no significant risk of mycotoxins to consumers after stored for 9 months in cold storage, and consumers can safely eat them. But multiple mycotoxins are detected simultaneously during the late stage of storage, which may pose health risks to humans. In order to clarify these health risks further, more toxicological data is needed.

Objective To develop a method for the determination of zearalenone (ZEN), ɑ-zearalenol (ɑ-ZOL) and β-zearalenol (β-ZOL) in maize flour by ultra performance liquid chromatography-tandem mass spectrometry, and assess the dietary exposure risk. Methods The samples were extracted by 70% acetonitrile-water (V/V), purified by QuEChERS, then detected by ultra performance liquid chromatography-tandem mass spectrometry in multiple reaction monitoring mode and quantified by matrix matching curve. The pollution index and hazard quotient (HQ) are used for dietary exposure risk assessment. Results ZEN, ɑ-ZOL and β-ZOL showed good linearity within the ranges of 0.2-100.0, 0.2-100.0 and 0.5-100.0 μg/L respectively. The limits of detection of ZEN, ɑ-ZOL and β-ZOL were 0.5, 0.5 and 1.5 μg/kg, respectively; the limits of quantitation were 1.5, 1.5 and 4.5 μg/kg respectively. Within the addition concentration range of 5.0-60.0 μg/kg, the recovery rates of the 3 kinds of target substances were between 80.4% and 103.0%, and the precisions were all less than 15%. This method was used to test 30 commercially available maize flour samples. The detection rate of ZEN was 80%, while α-ZOL and β-ZOL were not detected. The pollution index of ZEN was less than 0.7 and the HQ of ZEN was less than 1, it indicated that there was no risk and the threat to human health was small.Conclusion The method is sensitive, accurate and effective for routine monitoring of ZEN, α-ZOL and β-ZOL in maize flour. This method can be expected to use for the determination of the ZEN, α-ZOL and β-ZOL in other grain and its products.

Objective To establish a method for simultaneously determining the migration amounts of 24 kinds of organophosphate esters (OPEs), organophosphite antioxidants (OPAs), and parabens (PBs) in food contact materials by liquid chromatography-tandem mass spectrometry. Methods The food contact materials to be tested were subjected to migration experiments in accordance with the expected types of food and contact modes, so as to obtain the soaking solution. After centrifugation, the soaking solution was separated by liquid chromatography, determined by tandem mass spectrometry, and quantified by matrix-matched standard curve. Results The optimized method could simultaneously detect 24 kinds of OPEs, OPAs, and PBs in the migration soaking solutions of food contact materials. The limits of detection were 0.01-0.58 µg/L and the limits of quantitation were 0.03-2.00 µg/L. The spiked samples recovery rates ranged from 69.0%-129.6%, with relative standard deviations of 0.5% to 10.9% (n=6). The 20 packaging film bags, 10 disposable take-out boxes and 20 paper tableware items were tested. The ΣOPEs ranges were <limit of detection-19.1 μg/L, ΣOPAs were <limit of detection-1248 μg/L, and ΣPBs were <limit of detection-0.501 μg/L. The monitoring of the migration amounts of food contact materials was limited, its health risks required more attention and research. Conclusion This method is simple to operate and highly sensitive, which is suitable for the determination of the migration amounts of OPEs, OPAs and PBs in food contact material samples.

Objective To establish a method for the determination of 9 kinds of pesticide residues in black tea and green tea based on multi-walled carbon nanotubes (MWCNTs) combined with gas chromatography-tandem mass spectrometry (GC-MS/MS). Methods The key parameters were optimized by single factor experiment, including the amount of MWCNTs, ultrasonic extraction time and extraction solvent, and the methodological performance was evaluated, including linear range, detection limit, quantification limit, accuracy and precision. Results The linear relationship of this method was excellent, with correlation coefficients all greater than 0.99. The limits of detection and limits of quantitation were 0.002-0.004 mg/kg and 0.007-0.012 mg/kg, respectively. The recoveries of 9 kinds of pesticides in black tea and green tea were 71.52%-118.80%, and the relative standard deviation were 1.00%-6.92%. Conclusion This study successfully establishes a pesticide residue detection method based on MWCNTs combined with GC-MS/MS, which has the advantages of high sensitivity, high recovery rate and low solvent consumption, and significantly improves the detection efficiency. The actual sample detection shows that this method is suitable for the rapid screening of commercially available tea, and provides reliable technical support for the regulatory authorities.

Objective To establish a method for simultaneous determination of 23 kinds of per-and polyfluoroalkyl substances (PFASs) in food by high efficiency reinforced fat removal bilayer column-ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Methods The sample was extracted and centrifuged, high efficiency reinforced fat removal bilayer column method was adopted for the purification, the sample solution was separated on an Shim-pack GISS Hp 3 μm C₁₈ column using 2 mmol/L ammonium formate and methanol as mobile phase for gradient elution, detected by tandem mass spectrometry with multiple reactions monitoring (MRM), and quantified by internal standard method. Results The 23 kinds of target compounds of PFASs were well retained on the chromatographic column with good linearity in the range of 0.2-50.0 µg/L (r²>0.995). The limits of detection (LODs) and the limits of quantitation (LOQs) about perfluorobutanoic acid (PFBA) and perfluoropentanoic acid (PFPeA) were 0.06 μg/kg and 0.18 μg/kg respectively. LODs and LOQs about the remaining 21 kinds of perfluorinated compounds were 0.03 μg/kg and 0.09 μg/kg, respectively. The recoveries of the 23 kinds of target compounds of 2.0 μg/kg and 10.0 μg/kg spiked levels in the meat, fish and milk matrix ranged from 70.3%-120.0% with relative standard deviations of 1.56%-9.65%. Conclusion This method is easy, fast, accurate and sensitive, which is suitable for the determination of 23 kinds of PFASs in food.

Objective To establish a method for the determination of malachite green, crystal violet, leucomalachite green and leuco crystal violet in fish by solid-phase extraction (SPE) combine with ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Methods The sample was subjected to protein precipitation and extraction with acetonitrile, followed by pass-through purification using an HMR-Lipid SPE column. The analytes were then separated by the BEH shield C₁₈ chromatographic column using a mobile phase gradient with acetonitrile and ammonium acetate. The positive ion mode of the electrospray ionization source was used for multiple reaction monitoring (MRM) scanning, and the internal standard method was used for quantification. Results The linear ranges of the 4 kinds of target analytes were 0.20-10.00 ng/mL, with correlation coefficient (r) more than 0.999. The limit of detection was 0.05 μg/kg. The recoveries at 3 spiking levels (2, 5, 10 μg/kg) were 80.1%-105.2%, and the relative standard deviations were 1.2%-14.3%. Conclusion The method is rapid, sensitive and accurate, and is suitable for the determination of malachite green, crystal violet and their leuco metabolites in fish. It can provide support for quality control and market supervision.

Objective To investigate and analyze the current situation of pesticide residues in tea in Tongzhou District market of Beijing in 2024. Methods This study tested and analyzed 17 kinds of pesticide residues in 262 tea samples by using gas chromatography-tandem mass spectrometry (GC-MS/MS). Results The detection rate of pesticide residues in tea in Tongzhou District was 96.56%. Especially, the detection rate of chlorfenapyr was the highest (89.31%) and bifenthrin was the second (85.11%). Furthermore, two kinds of prohibited pesticides (methyl parathion and methamidophos) and 2 kinds of restricted pesticides (fenvalerate and ethoprophos) were detected. These 4 kinds of harmful pesticides exceeded the maximum residue limits. In addition, the obsolete pesticide hexachlorobenzene was detected in other 5 samples. The analysis of residue characteristics revealed that 75.57% of the samples had 2-5 kinds of compound residues, of which oolong tea had the most residues. There were 6 tea detected to have excessive pesticide residues. The exceedance rate in descending order was white tea (12.20%), oolong tea (10.77%), dark tea (8.11%), green tea (6.52%), yellow tea (5.88%), black tea (1.79%). There was no significant difference in pesticide detection rate among different markets (P>0.05). Conclusion The detection rate of pesticide residues in tea in Beijing Tongzhou market is high, and complex pollution is common, but the overall over-standard rate is low (7.63%). The presence of prohibited and restricted pesticides in some samples highlights the need for stricter source control and routine monitoring by relevant authorities to ensure tea quality and safety.

Objective To grasp the distribution and epidemic characteristics of the pathogen spectrum of foodborne diseases in Yanqing District, Beijing. Methods From 2018 to 2023, stool samples were collected from patients with foodborne diseases in two sentinel hospitals in Yanqing District of Beijing to isolate and culture intestinal pathogens and detect norovirus nucleic acid, and the test results were analyzed. Results From 2018 to 2023, a total of 1644 case samples were collected, and 285 pathogen strains were detected, with a total detection rate of 17.34%. The composition ratio of the pathogen spectrum from high to low was as follows: Diarrheagenic Escherichia coli 41.40%, norovirus 22.11%, Salmonella 16.49%, Campylobacter 15.44%, Vibrio parahaemolyticus 4.21%, Vibrio vulnificus 0.35%, and Shigella was not detected. A total of 270 infected cases were detected, with a mixed infection rate of 5.56%. The pathogen spectrum had annual variation characteristics. The peak detection period for bacterial foodborne diseases was summer and autumn, while norovirus was detected throughout the year. The male-to-female ratio was 1.26:1. The high-risk group was the 25-<45 age group. Among occupations, the infection rate was highest among cadres and staff. Among them, the detection rates of Vibrio parahaemolyticus and norovirus were the highest among cadres and staff, while the detection rate of diarrheagenic Escherichia coli was the highest among catering and food industry personnel. The suspected exposure foods causing the highest to lowest positive rates of pathogens were beverages and frozen desserts, meat and meat products and other foods. Among them, aquatic animals and their products had the highest detection rate of Vibrio parahaemolyticus, beverages and frozen desserts had the highest detection rate of diarrheagenic Escherichia coli, and unknown foods had the highest detection rate of norovirus. Conclusion The pathogen spectrum of foodborne diseases in Yanqing District of Beijing from 2018 to 2023 has regional characteristics. The prevention of foodborne diseases cause by consumption of beverages and frozen beverages, aquatic animals and their products, meat and meat products in people aged 25-<45 years in summer and autumn, and the epidemiological characteristics of norovirus should be focused on monitoring, so as to provide scientific basis for public health decision-making in this area, protect the people’s rights and interests in health.