Abstract:Inspection method standard is an important part of food safety standard system, the paper mainly explains intension of food safety inspection method standard, introduces the status quo and existing problems of physical and chemical, microbial, toxicology, parasite method standard and basic inspection method standard. The paper puts forward suggestions from the aspects of improving the applicability of inspection method standard, strengthening the ability of technical management of inspection method and standards, strengthening the fundamental research and international communication and cooperation, and building a comprehensive, multi-level and holistic inspection method system.

Abstract:Objective To understand the antimicrobial resistance of Escherichia coli recovered from breeding and slaughtering of broiler chickens, and to explore the impact of disinfectant use on resistance during COVID-19 pandemic. Methods A total of 722 strains of Echerichia coli, isolated from broiler farms and slaughterhouses in Henan, Shandong and Liaoning provinces, were tested for resistance of 27 kinds of antimicrobial compouds belonging to 12 categories using broth dilution method, and the changes of antimicrobial resistance of strains from Shandong province before and after the outbreak of COVID-19 were analyzed. Results An overall high level antimicrobial resistance was found among 722 Escherichia coli isolates, 96% of which were drug resistant strains. The resistance rate of 9 drugs in 6 categories, including AMP, was higher than 75% with the highest one of 88.1%, eight drugs got the intermediary rate of over 10%, and multiple drug resistant strains accounted for 94.7% of all resistant strains; a total of 517 drug resistance profiles were found. The strains resistant to 10 and 9 drugs ranked the top, and 118 strains were resistant to 11 kinds of antimicrobial compounds at the same time, with 2 of which were resistant to 24 drugs. Resistance of Escherichia coli isolates in Shandong province to DOX, PB and AMS/AMC increased significantly after COVID-19 pandemic. Conclusion The overall antimicrobial resistance of Escherichia coli isolates recovered from broiler farms and slaughterhouses in China is at a very high level, and the multi-drug resistance is serious, which may be related to the long-term widespread use of related drugs in the upstream of the food chain. During the COVID-19 outbreaks, the disinfection measures in broiler breeding and slaughter processing might be related to the enhancement of the Escherichia coli antimicrobial resistance to some drugs. Continuous active surveillance from a preventive perspective should be carried out to fully assess the upside risk to antimicrobial resistance of the pathogens recovered from resistance risk in the food chain by the use of disinfectants. needs in the pandemic.

Abstract:Objective The epidemiological characteristics of foodborne disease outbreaks in China in 2019 were analyzed to provide scientific basis for further adjustment on prevention and control strategies. Methods The data of foodborne disease outbreaks collected by National Foodborne Disease Outbreaks Surveillance System were used to analyze the epidemiological characteristics through descriptive statistics. Results A total of 6 390 foodborne disease outbreaks were reported in China, resulting in 38 797 illnesses and 134 deaths from 30 provinces (autonomous regions and municipalities) and Xinjiang Production and Construction Corps(except Tibet). Among the 3 572 confirmed single etiologic agents, microbial pathogens were the most common cause of outbreaks accounting for 52.01% of the illnesses(12 738/24 491). Poisonous mushroom caused the largest percentage of outbreaks and deaths, accounting for 44.96%(1 606/3 572) and 57.60%(72/125) respectively. In settings of foodborne disease outbreaks, catering services accounted for 49.95% of the illnesses(3 192/6 390) and 70.00% of the outbreaks(27 156/38 797), households had the largest number of deaths, accounting for 80.60%(108/134). Conclusion Foodborne disease outbreaks mainly occurred in catering services. Microbial pathogens remained the top cause of illnesses in China, poisonous mushrooms caused the largest deaths. The supervision and management of food safety and health education should be strengthened and effective measures should be taken for high risk food, main site and major pathogenic factors to reduce the burden of foodborne diseases.

Abstract:Objective Based on the food categories, risk types and statistical and characteristic analysis of risk factors of foodborne diseases incidents that occurred in China in previous years, rating method of food safety risk assessment in major events were researched in order to provide theory guidance for scientific prevention and control system. Methods Combining data of foodborne diseases in China from 2002 to 2017, the probability of occurrence of risk factors and the severity of risk outcomes were statistically analyzed, and food safety risk rating in major events was carry out according to Australia and New Zealand risk assessment method. Results Foodborne diseases involving high risk food categories and the proportion of occurrence were mainly vegetables and their products (29%), meat and meat products (26%), aquatic and its products (17%), grains and their products (10%), fungi and its products (8%). Microbial poisoning were the main factor of foodborne disease incidents. The number of chemical poisoning incidents and the number of deaths showed a significant decline year by year. Ingestion of poisonous animals, plants and poisonous mushrooms had become the main cause of deaths. The risk assessment of 34 risk factors was basically concentrated on extremely serious risk (level E), high risk (level H) and medium risk (level M), accounting for 56%, 21% and 23% of the 34 risk factors, respectively. The risk of bacterial incidents was mostly at a very serious risk level (level E), viruses and mycotoxins were at a high risk level (level H), and parasites were at a medium risk level (level M). In addition to clenbuterol poisoning, histamine poisoning and germinating potato poisoning, nitrite poisoning, poisonous plants and animals, and poisonous mushrooms belonged to the extremely serious risk level (level E). Conclusion The overall risk of foodborne diseases in major events is relatively high. It is recommended that relevant departments combine the result of risk food and factor assessment and classification to carry out monitoring, prevention and control in key point such as procurement and storage, heating and sterilization, cross-contamination and personnel health.

Abstract:Objective Based on the fact that the quality control bacteria used for bacterial drug sensitivity determination are commonly sensitive to antibiotics, while most foodborne pathogens isolated in China are relatively tolerant to these antibiotics, the concentration range of antibiotics used for antimicrobial sensitivity test is very wide, which resulting in antibiotic wastes and inaccurate test result. Methods In this study, five standard samples with clear minimum inhibitory concentration (MIC) were successfully developed for sensitivity test of common antibiotics(streptomycin, gentamicin, chloramphenicol, cefoxitin and ampicillin). Agar dilution and microbroth dilution method were respectively used to determine the susceptibility of isolates to the antibiotics, the reference strains were developed via vacuum freeze-drying. Results The reference strains with clear MICs assignment of streptomycin, gentamicin, chloramphenicol, cefoxitin and ampicillin were developed respectively. The antibiotic susceptibility of the reference strains was genetically stable, and the uniform and storage stability of them were good. When stored at 37 ℃ for 13 d, 4 ℃ for 90 d and -80 ℃ for 360 d, respectively, the viable bacteria number basically remained above 10⁵ CFU/vial. All confirmed antibiotic resistance phenotypes could be detected, and the MICs value of the certain antibiotics did not show apparent fluctuation or drift. Conclusion The development of reference strains that in line with the characteristics of drug resistance of foodborne pathogens in China with clear MICs assignment to certain antibiotics would help to enrich the types of reference strains in China, and further strengthen the monitoring of drug-resistant bacteria to ensure food safety and public health.

Abstract:Objective To develop an analytical method for determination bisphenol A, bisphenol F and bisphenol S in fruit (apple), vegetable (spinach), cereal (rice flour) and infant cereal supplement (infant formula rice flour) by compound immunoaffinity column coupled with high performance liquid chromatography Tandem Mass Spectrometry. Methods The samples were extracted with acetonitrile or 80% methanol solution, purified by a compound immunoaffinity column, separated by ACQUITY UPLC BEH C₁₈ column, and detected by HPLC-MS/MS. Results The linearity of the three bisphenol compounds in the corresponding concentration range was good with relative coefficient of R² greater than 0.999. The recoveries of the three kinds of bisphenol were in the range of 94.81%-111.12%, the relative standard deviations were in the range of 1.25%-11.50%, and the matrix effect was in the range of -10.23%-5.46% at low, medium and high spiked concentrations. The limits of detection were 0.015-0.15 μg/kg and the limits of quantification were 0.05-0.5 μg/kg. Conclusion This method is based on antigen and antibody specific binding immunoaffinity column to purify the samples, with good reproducibility and high sensitivity, and can effectively separate and detect bisphenol substances in apple, spinach, rice flour and infant formula rice flour. It could be applied to the qualitative and quantitative detection of bisphenol substances in these four kinds of food.

Abstract:Objective To develop an analytical method for determination of masked fumonisins in cereals by isotope dilution-ultra high performance liquid chromatography-tandem mass spectrometry. Methods The samples were extracted and diluted for determination of parental fumonisins. Another portion of extracted samples were alkaline hydrolyzed and cleaned up using strong anionic exchange adsorbent (MAX) for determination of hydrolyzed fumonisins. The chromatographic separation was performed on a CORTECS C18 column (2.1 mm×100 mm, 1.6 μm) using 0.2% formic acid aqueous solution and methanol with 0.2% formic acid as the mobile phase under gradient elution. The six fumonisins of FB1, FB2, FB3, HFB1, HFB2 and HFB3 were analyzed by tandem mass spectrometry using multiple reactions monitoring (MRM) mode. The isotope dilution method was applied for quantitative analysis. Results The six fumonisins showed good linearity with relative coefficients above 0.99. Limits of quantitation (LOQs) were in the range of 5.0-10 μg/kg. At the low, medium and high-spiked levels, the recoveries of fumonisins in three types of cereals were from 88.01% to 114.21%, with precision (RSD) of 0.72%-11.5%. Conclusion This method is accurate, sensitive and reproducible for the determination of masked fumonisins in cereals. It is suitable for the routine test in analytical chemistry laboratories for monitoring masked fumonisins levels in cereals.

Abstract:Objective Reference material candidates of bisphenol A, bisphenol S, bisphenol F and bisphenol AF in infant formula milk powders were prepared, in order to provide technical basis and methodology for the further formation of certified reference materials, and fill the research gap in this field. Methods The commercial infant formula milk powders were selected to prepare the reference material candidates by the processes of water dissolution, standard addition, homogenization, drying, crushing, screening and packaging. The concentrations of the target compounds were determined by isotope dilution-liquid chromatography tandem mass spectrometry. 25 bottles of samples were randomly selected for homogeneity study, and F test was used for statistical analysis. The long-term and short-term stability were studied by the quantitative analysis of samples stored at 25 ℃ for 12 months and at 60 ℃ for 7 d, respectively, and evaluated by univariate linear simulation equation. Results The homogeneity and stability result of the prepared reference material candidates were satisfactory, which met the expected requirements. Conclusion This work was expected to fill the gap in preparation of matrix reference materials for bisphenol A analogues, and provid material basis and technical support for the monitoring of bisphenol A analogues in food.

Abstract:Objective In order to explore the contamination and drug resistance of foodborne pathogens in fresh cut fruits and vegetables, samples were collected from retail markets in five district in Beijing. Methods The national standard method of food microbiological examination was used to detect Staphylococcus aureus, Salmonella, Listeria monocytogenes and Escherichia coli respectively. The drug resistance of the isolates was determined, and the Diarrheagenic Escherichia coli was screened by fluorescent PCR. Results Among 326 fresh cut fruits and vegetables sold in Beijing, the contamination rates of Staphylococcus aureus, Listeria monocytogenes, Salmonella, Escherichia coli and Enteroaggregative Escherichia coli were 15.34%, 1.84%, 0%, 9.51% and 1.23% respectively. 50 strains of Staphylococcus aureus isolated in this study were mainly resistant to penicillin (90.00%) and oxacillin (48.00%), 31 strains of Escherichia coli were mainly resistant to compound sulfamethoxazole (67.74%) and ampicillin (64.50%), and 4 strains of Enteroaggregative Escherichia coli showed multiple drug resistance. All 6 strains of Listeria monocytogenes were sensitive to 10 kinds of antibiotics. Conclusion This research provided a scientific experimental basis for formulating the prevention and control strategy of foodborne diseases.

Abstract:Objective To determine the antimicrobial susceptibilities of 33 Listeria monocytogenes cultured from ready-to-eat (RTE) meats in China and to use whole genome sequencing (WGS) to characterize the antimicrobial resistance and virulence genotypes of these isolates. Methods The susceptibilities of 33 Listeria monocytogenes were determined by broth microdilution. These isolates were then sequenced using short-read high accuracy protocols. The corresponding genomes were assembled and further analysis was carried out using appropriate bioinformatics pipelines. Results All isolates were found to be susceptible to ampicillin, trimethoprim-sulfamethoxazole, gentamicin, meropenem and vancomycin. One isolate was resistant to tetracycline and erythromycin at the same time. All 33 L. monocytogenes were classified into 13 STs, among them ST9, ST87, ST122 were the dominant, from which resistant isolate belonged to ST87. The genotypes of the resistant isolate correlated well with its resistant phenotype. Up and down stream analysis of the genetic context, in which these resistant genes were found, suggested that they may have been acquired from Erysipelothrix rhusiopathiae and Blautia product. All isolates harboured LIPI-1 and LIPI-2,7 of them harbored LIPI-3, and 8 harboured LIPI-4(1 ST121 and 7 ST87). Conclusion These data showed that acquired resistance existed in this bacterium from RTE meats origins, and can be a potential public health risk due to its high harboring rate of LIPI-3 and LIPI-4. It was suggested that the monitoring of L. monocytogenes in RTE meats should be strengthened in the future, specifically for ST87.

Abstract:Objective Amino acids, vitamins and inorganic salts were used to replace beef extract and peptone to develop a selective medium with controllable quality for Salmonella. Methods Effects of 20 kinds of amino acids, 11 kinds of vitamins or 4 kinds of inorganic salts on the growth characteristics of Escherichia coli ATCC 25922 were studied, and the optimal concentration was determined. The beef extract and peptone in bismuth sulfite (BS) agar or Hektoen Enteric (HE) agar were replaced, and the chemically defined BS agar or HE agar was developed. Results Adding asparagine, aspartic acid, valine, thiamine hydrochloride or riboflavin to the basic medium was the most favorable for the growth of Escherichia coli ATCC 25922, and the OD₅₉₅ were all higher than 0.1. However, adding serine, lysine hydrochloride, isoleucine, nicotinic acid, biotin or disodium hydrogen phosphate to the basic medium did not promote the proliferation of Escherichia coli, and the OD₅₉₅ was almost 0. The chemically defined BS agar or HE agar was prepared by replacing beef extract, peptone with 35 kinds of nutrients according to the optimal concentration. After verification of quality control strains, chemically defined BS agar or HE agar was similar to commercial medium in cell growth index, colony morphology and special color reaction. Conclusion Chemically defined BS agar or HE agar meet the quality requirements of national standard.

Abstract:Objective To understand the contamination of pathogens and the antibiotics resistance characterization in raw milk in China. Methods A total of 53 raw milk samples collected from 43 pastures in different regions in China from September to November in 2019 were detected the contamination of six pathogens, and isolates were tested for the antibiotic resistant ability. Results The contamination rates of Escherichia coli, Staphylococcus aureus, Bacillus cereus and Listeria monocytogenes were 62.26%(33/53), 20.75%(11/53), 5.66%(3/53)and 3.77%(2/53), respectively. The detection of Cronobacter and Salmonella were negative. A total of 117 isolates were selected for antibiotics resistance test and 58 strains were resistant to antibiotics, accounted for 49.57%(58/117). 33 of 90 gram-negative strains were resistant strains, accounted for 36.67%(33/90). 25 of 27 gram-positive bacteria were resistant strains, accounted for 92.59%(25/17). Conclusion The bacterial contamination in raw milk collected from pastures in different regions was quite different, and showed a downward trend with the decrease of temperature. Isolates from raw milk showed a high multiple antibiotics resistance rate, suggesting a cautious control of veterinary antibiotics should be adopted.

Abstract:Objective A method for the preparation and certification of the reference material of tenuazonic acid(TeA) and tentoxin (TEN) in wheat flour was developed. Methods The reference material of TeA and TEN in wheat flour was prepared from grain which naturally contaminated alternaria toxins, characterizated with national standard regulation. Results The reference materials of TeA and TEN in wheat flour which contains two values were developed. The reference materials were approved the second class of National Certified Reference Materials [GBW(E) 100547 and GBW(E) 100548]. Conclusion The reference materials are currently the only National Certified Reference Materials of wheat flour that naturally contaminate TeA and TEN. The reference materials provides important method ological reference for the development of matrix reference materials with new mycotoxins in grain in China.

Abstract:Objective To investigate the culture effect of MRS AGAR medium of 5 domestic brands and 2 imported brands on lactic acid bacteria, and to compare the product quality. Methods Using spiral coating counting method, the growth of 3 strains of lactobacillus specified in GB 4789.28—2013 and 9 strains of non-national standard Lactobacillus (including standard strains and laboratory isolated strains) on the different MRS AGAR medium were quantitatively determined. By comparing the growth rate of different brands of medium to different strains, the quality of each brand of medium was evaluated. Results There were significant differences in the growth rate of GB 4789.28 standard strain on different brands of MRS AGAR media, and some of the medium had quality problems. Streptococcus thermophilus ST-21 isolated from probiotics powder had good growth ability in reference medium, and there were significant differences in growth rate among different brands of MRS AGAR medium. Conclusion The result of this study indicated that there are great differences in the quality of MRS AGAR media of different brands at home and abroad; Streptococcus thermophilus S-T21 can effectively evaluate the quality difference of different brands of media, and is suitable for the quality control of MRS AGAR media.

Abstract:Objective To evaluate the exposure level and health risk of inorganic arsenic ingested by rice in Chinese residents. Methods The data of inorganic arsenic content in rice published in PubMed, CNKI and other databases from 2001 to 2020 were systematically retrieved. Combined with the monitoring data of nutrition and health status of Chinese residents in 2012, the inorganic arsenic intake level of Chinese residents through rice was estimated by semi parametric Monte Carlo simulation. Target hazard quotient method and lifetime cancer risk method were used to evaluate the health risk caused by inorganic arsenic in rice. Results The content of inorganic arsenic in rice ranged from 0.038 to 0.1 mg/kg. The average level of inorganic arsenic exposure of Chinese residents through rice was higher in the south than in the north(p＜0.05), especially in Jiangxi [1.00,0.59,0.48 μg/(kg·BW·d)], Hunan [0.58,0.39,0.38 μg/(kg·BW·d)], Guangxi [0.57,0.40,0.34 μg/(kg·BW·d)] and other provinces and autonomous regions in the south. The risk assessment result of people of different ages in various provinces, cities and autonomous regions show that the inorganic arsenic exposure of people with high consumption of rice may have health risks, among which the risk of people with high consumption of rice (P95) is higher among residents aged 2-17 in Jiangxi, Hunan and other provinces. The THQ value range of each provinces, cities and autonomous regions is 0.08-6.96, and the LCR value range is 0.38×10-4-3.13×10-3. Conclusion Inorganic arsenic ingested by rice may pose a certain health risk to the high rice consumption population among Chinese residents.

Abstract:Objective The migration of three kinds of UV absorbants [2-hydroxy-4-methoxybenzophenone (UV-9), 2-(2-hydroxy-5-methylphenyl)benzotriazole (UV-71) and 2-hydroxy-4-n-octyloxybenzophenone (UV-531)]in low density polyethylene (LDPE) food contact materials under different conditions was studied. Based on the Piringer deterministic migration model, the important parameters — distribution coefficient and diffusion coefficient — of adsorption and diffusion were obtained, and the migration law were studied. Methods LDPE powder and three kinds of UV absorbents were mixed and granulated by twin screw extruder, and the film was formed at 175-180 ℃ and 70 Pa. Simulating processing and storage of high-concentration alcoholic food, 50%, 70% and 95% ethanol were used as food simulations, and the migration tests were carried out under 20,40 and 60 ℃. Ultra-high performance liquid chromatography (UPLC) was used to determine the migration content of UV absorbents at different time points. The diffusion coefficient and distribution coefficient were obtained by fitting the data with Piringer model. The influence of temperature, food simulants, and target content on migration were studied. Results Temperature had the greatest effect on migration. With the increase of temperature, the diffusion coefficient of UV absorbents increased and the distribution coefficient decreased. The effect of ethanol content in food simulants on the diffusion coefficient of UV absorbent was not significant, but the distribution coefficient decreased with the increase of ethanol content. The content of UV absorbent had the least effect on the migration, and the diffusion coefficient and distribution coefficient had no obviously change (except that the distribution coefficient of UV-71 decreased with the increase of the content). Conclusion The Piringer deterministic model was used to study the diffusion coefficient and distribution coefficient of the migration of three kinds of UV absorbents in LDPE to high concentration alcoholic food simulant, which provided an effective method for the risk assessment of UV absorbents in food contact materials.

Abstract:Objective To investigate the zinc oxide nanoparticles (ZnO-Np) migration characteristics in the food contact material, namely polyvinyl chloride (PVC). MethodsIn this study, PVC/ZnO-Np composite with 1% w/w of ZnO-Np was prepared. Single-particle system tandem inductively coupled plasma mass spectrometry (Sp-ICP/MS) was used for the particle size detecting of ZnO-Np during migration. Meanwhile, under the migration conditions of 20 ℃, 40 ℃ and 70 ℃, the total Zn content in food simulants, 3% acetic acid and 95% ethanol, was determined by ICP/MS as a means of analyzing ZnO-Np specific migration, migration rate, nanoparticle size and migration morphology. Results The initial content of ZnO-Np in the composites was 8.43 g/kg. Migration experiments showed a minimum value of (9.27±3.37) mg/kg and a maximum value of (1 947.33±75.02) mg/kg for the specific migration at different time points. The median particle size ranged from 28 nm to 1 156 nm. Migration rates at day 15 ranged from 5.42% to 23.01%. Conclusion The migration of ZnO-Np in PVC is caused by surface migration and material swelling, and aggregation occurs during the migration process. The applicability and safety of PVC/ZnO-Np composites for acidic, fatty, and high-temperature foods should be of ongoing concern.

Abstract:Objective To he aim of this study was to preliminarily study the toxicity of combined exposure of low-dose of four polycyclic aromatic hydrocarbons. Methods 8-week-old male SD rats were randomly divided into 5 groups with 10 rats each, and 0,10, 50,250 and 1 000 μg/kg·BW dose were continuously administered by gavage. Based on the actual exposure of four polycyclic aromatic hydrocarbons in human body, the proportion of gavage dose was set as benzo [a] pyrene∶benzo [a] anthracene∶chrysene∶benzo [b] fluoranthene=0.99∶2.92∶2.68∶1.68. The rats were sacrificed 30 days after exposure. Biological samples such as serum and organs were taken, organ coefficients were calculated, pathological sections of rat liver were made, pathological changes were observed, and liver function related indexes, oxidative stress related indexes and lipid metabolism related indexes were detected. Results Compared with the control group, the liver structure of the rats in the exposure group was significantly abnormal, the hepatic sinuses were enlarged, and the hepatocytes showed balloon-like change. The liver organ ratio was significantly increased in 1 000 μg/kg·BW group. After 30 d of exposure, serum aspartate aminotransferase (AST) increased significantly in 1 000 μg/kg·BW group (P<0.05). Serum glutathione peroxidase (GSH-Px) in the exposure groups increased significantly at 30 d (P<0.05). After 30 d of exposure, in 1 000 μg/kg·BW group, serum high density lipoprotein cholesterol (HDL-C) decreased significantly and liver cholesterol (TC) increased significantly (P<0.05). Serum triglyceride (TG) of rats in 250 μg/kg·BW increased significantly (P<0.05), and TG in liver of rats exposed to 50 μg/kg·BW or more increased significantly (P<0.05). Conclusion Low dose combined exposure to pah4 has adverse effects of liver injury, oxidative stress and lipid metabolism disorder in SD male rats.

Abstract:Objective To prepare reference materials of dioxins and dioxin-like polychlorinated biphenyls in fish powder matrix. Methods Using fly ash to feed grass carp, the fish samples were peeled, homogenized, dried, packed and sterilized. After homogeneity and stability studies, coordinated values were determined by 8 laboratories, and the uncertainty was evaluated. Results The reference material had good uniformity and the stability was more than 12 months. The characteristic values of PCDD/Fs were 0.017-1.4 pg/g, the expanded uncertainty were 0.02-0.6 pg/g and the characteristic values of DL-PCBs were 0.54-16 pg/g, expanded uncertainty were 0.28-6 pg/g. The matrix reference material was approved by the evaluation committee(GBW(E)100741). Conclusion The matrix reference material has good homogeneity and stability, which can be used in the quality control for analyzing, laboratory ability verification, analytical instrument calibration, analysis method accuracy evaluation and verification, etc.

Abstract:Objective To establish a method for determination of the content of chloramphenicol in milk powder by liquid chromatography-mass spectrometry, and apply it to test the uniformity and stability of reference material and determine the value. Methods The milk powder was reconstituted by adding water, extracted with ethyl acetate, degreased with n-hexane, extracted with ethyl acetate again, and finally quantified by the isotope internal standard method. Results Chloramphenicol had a good linear relationship in the range of 0.4-4.0 ng/mL, the correlation coefficient was 0.999, the average recovery rate was 100.5%, the relative standard deviation was 1.1%-3.2% (n=6), and this method had a weak matrix effect in milk matrix. Conclusion The method is accurate and reliable, and can be used for the determination of reference materials. After jointly determination by 11 laboratories, the characteristic value and the expanded uncertainty (k=2) of the reference material for the analysis of chloramphenicol residues in milk powder are(1.92±0.30) μg/kg and(5.65±0.53) μg/kg.

Abstract:Objective To detect the content of Cadmium (Cd) in crab sold in Beijing from 2018 to 2020 and carry out health risk assessment. Methods Random sampling method was adopted, common crab sold in Beijing were sampled. The content of Cd was determined by atomic absorption spectroscopy to evaluate the health risk. Results A total of 83 crab samples were collected. The average level of Cd in crabs was 0.647 mg/kg. Among them, the Cd content in freshwater crabs ranged from 0.043-0.620 mg/kg with the average level of 0.183 mg/kg. Whereas, the concentration of Cd in seawater crabs ranged from 0.033-3.200 mg/kg with the average level of 1.070 mg/kg. Moreover, the difference of the over-limit ratio was significant during three year. The THQ value and total THQ value of heavy metals in crab ingested by children and adults decreased in turn. The THQ values of Cd were less than 1. Conclusion Although the results indicated that there were certain amounts of Cd residues in the crabs sold in Beijing during 2018-2020, the dietary risk was relatively low because of the low intake.

Abstract:Objective To investigate and analyze the contamination of 12 mycotoxins in unprocessed wheat grain samples from four provinces of China in 2019. Methods A total of 289 wheat grain samples harvested in 2019 from He'nan, Hebei, Anhui and Shandong provinces of China were collected and analyzed for 12 kinds of mycotoxins, including 8 Fusarium toxins and 4 aflatoxins by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Results Deoxynivalenol (DON) was the predominant mycotoxin in wheat samples, and the positive rate and the average level of DON were 95.5% (276/289) and 135.9 μg/kg. While the positive rates and the average levels of 15-acetyl-deoxynivalenol (15-Ac-DON) and 3-acetyl-deoxynivalenol (3-Ac-DON) were 37.4% (108/289) and 4.4 μg/kg, 36.7% (106/289) and 5.2 g/kg, respectively. The positive rates and the average levels of the rest of 8 Fusarium toxins and 4 aflatoxins were relatively low. There was no significant difference in mycotoxins contamination levels among the four provinces. Among 289 wheat samples, 59.9% (173/289) samples were simultaneously contaminated with more than 2 mycotoxins with DON and its derivatives 15-Ac-DON and/or 3-Ac-DON being the frequent combination. Conclusion DON is the predominant mycotoxin in wheat samples in China and the incidence of co-occurrence of DON and its derivatives, 3-Ac-DON and/or 15-Ac-DON are high. The positive rate and contamination levels of aflatoxins and other Fusarium toxins are relatively low. These results suggest that there should be a continuous monitoring for the contamination of fusarium mycotoxins, especially DON and its derivatives, in wheat in China.

Abstract:Objective To explore the concentrations of rare earth elements (Rare earth elements, REEs) in drinking water in rare earth mining and non-mining areas in Shandong, Guangdong, and Jiangxi provinces of China. Methods Typical rare earth mining areas and 3 non-mining areas in the 3 provinces were selected for investigation. Drinking water of people in mining areas and non-mining areas were collected for 3 consecutive days by duplicate portion method. The contents of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc and Y in water samples were determined by inductively coupled plasma mass spectrometry (ICP-MS). Results The detection rate of each REEs in drinking water of mining and non-mining area was 12.98% to 86.64% and 1.07% to 69.04%, respectively. The average content of total REEs in drinking water in the mining area was 6.974 μg/L, with the maximum of 178.290 μg/L. The main elements were Ce, La, Nd, Y, Sc and Pr (≈90.0%). The average content of total REEs in drinking water in non-mining area was 0.772 μg/L, significantly lower than that in mining area (P<0.05); except for Tb, Ho and Tm, the contents of other REEs in drinking water from mining areas were significantly higher than those from non-mining areas (P<0.05). The total REEs contents in drinking water of mining areas in Guangdong and Jiangxi provinces were higher than that of non-mining areas (P<0.05), which were 90 times and 2 times of those of non-mining areas in average respectively. The average content of total REEs in drinking water of mining area in Shandong was higher than that of non-mining area, but with no statistical difference (P>0.05). Conclusion The contents of REEs in drinking water of mining area are higher than that of non-mining areas. Risk assessment of REEs exposure by drinking water should be further carried out for residents in mining areas.

Abstract:Objective Combined the traditional isolation culture, ITS sequencing and metagenomics sequencing technology to establish a new method for the analysis of fungal community composition and species diversity in Pu'er tea at retail markets. Methods Pu'er tea samples were collected at retail markets and tested for cultivable fungi in accordance with “National food safety standard Food microbiological examination:Counting of Molds and Yeasts”(GB 4789.15—2016), and the isolated strains were sequenced by ITS and analyzed in the NCBI database; the fungal genomic DNA from Pu'er tea samples was extracted by CTAB method, and performed PCR amplification and amplicon sequencing; high-throughput sequencing data was used to build OTUs clustering, and carried out species composition and diversity analysis. Results Twelve fungi were isolated and cultured from Pu'er tea samples, mainly Aspergillus and Lichtheimia, of which Aspergillus niger had the highest proportion (25%, 3/12). The result of species distribution based on metagenomics showed that the diversity and uniformity of fungal species in Pu'er tea samples were low, and there were relatively high number of dominant species; the highest proportion of fungi was Ascomycota (74.03%), and at the genus level, the fungi in Pu'er tea were dominated by Blastobotrys (49.43%) while Aspergillus accounted for a relatively low percentage (14.04%). Conclusion This study comprehensively applied traditional isolation culture, molecular biology and high-throughput metagenomics sequencing technology to establish a new method for the analysis of fungal community composition and species diversity in Pu'er tea at retail markets. investigate the fungal community structure in Pu'er tea and whether it would contaminate toxin-producing strains such as Aspergillus flavus. It provided ideas and references for further research on the microbial community structure in Pu'er tea and its impacts on quality and safety.

Abstract:Objective To establish an analysis method for simultaneous determination of 15 kinds of pyrrolizidine alkaloids (PAs) in tea by ultra-high performance liquid chromatography-high resolution mass spectrometry. Methods Formic acid aqueous solution and methanol were used as extraction solvent. After the ultrasonic extraction and MCX solid phase extraction purification, the analytes were separated with HSS T3 chromatographic column (50 mm×2.1 mm,1.7 μm) using 4.0 mmol/L ammonium formate solution(0.1% formic acidinclusive) and methanol as mobile phase for gradient elution. Finally, the eluents were determined by full scan/data independent acquisition (Full MS/DIA) of high resolution mass spectrometry in positive mode. Results Depending on the comprehensive data, the characteristic structural fragment ions of 3 kinds of PAs were screened out. Good linearities in the range of 0.5-200 μg/L were observed for 15 kinds of PAs (R²＞0.99), the limits of detection (LODs) and the limits of quantification (LOQs) were 0.35-4.69 μg/kg and 1.18-11.17 μg/kg, respectively. In this study, 20 commercial tea samples were analyzed using this method, and Jacobine was detected in 1 camomile tea sample, all the other measured values were lower than the LODs in the method. Conclusion This method has high sensitivity and stability, can meet the simultaneous detection requirements of 15 kinds of PAs in tea.

Abstract:Objective To establish a rapid determination method for As, Cd and Pb in food by X-ray fluorescence spectrometry combined with fundamental parameter method. Methods The food samples were crushed and screened, and then the test samples were prepared and the quantitative analysis and rapid screening analysis were performed by XRF combined with fundamental parameter method. Results The experimental result showed that the detection limits (mg/kg) of As, Cd and Pb of XRF were 0.07,0.06, and 0.07, respectively. At the limit of quantitation level of GB 2762—2017 for food, the relative difference of XRF detection result of As, Cd and Pb were less than 25% compared with ICPMS. For the rapid detection of cereals, beans, meat products and aquatic products samples, XRF result showed that, the false positive rate and false negative rate of As, Cd and Pb were less than 5%, except for a few food types. Conclusion The method was suitable for screening analysis of arsenic, lead and cadmium in different food samples with the advantage of simple, rapid and highly sensitive.

Abstract:Objective To establish a method for the determination of chlorate and perchlorate in seasoning samples by ultra-performance liquid chromatography tandems mass spectrometry (UPLC-MS/MS). Methods Seasoning sample was ultrasonically extracted with acidic acetonitrile solution, and then purified with a graphitized carbon black (GCB) cartridge and an Ag/H cartridge. UPLC-MS/MS analysis was conducted under multi-reaction monitoring mode with isotope-labelled internal standard calibration for quantification. Results Chlorate and perchlorate showed a good linearity (R²≥0.99) in the range of 1-1 000 μg/L and 0.1-100 μg/L, respectively. The limits of detection for chlorate and perchlorate were 3.0 μg/kg and 0.3 μg/kg, as well as the limits of quantification were 10 μg/kg and 1.0 μg/kg, respectively. The average recoveries of two compounds in seasoning samples at three spiked levels were 86.5%-113.7% and the relative standard deviations were 1.8%-15.3%. The detection rates of chlorate and perchlorate from 122 seasoning samples were 76.2% and 93.4%, with the maximum concentration of 30.4 mg/kg and 12.3 mg/kg, respectively. Conclusion The method is suitable for qualitative and quantitative analysis of chlorate and perchlorate in seasoning. Further study should be focused on the perchlorate in seasoning products since its relative prevalence contamination.

Abstract:Objective To prepare Cronobacter spp. (Enterobacter sakazakii) proficiency test samples which meet the requirements of uniformity and stability, and use them for proficiency test. Methods The background strains and Cronobacter. spp were identified by biochemical and matrix-assisted laser desorption ionization time of flight mass spectrometry method. Freeze-drying was used to prepare the samples with 10⁴CFU/bottle. According to Guidance on Evaluating the Homogeneity and Stability of Samples Used for Proficiency Testing, 20 samples were selected randomly for uniformity test. The samples were stored at -20 and 4 ℃ respectively to evaluate the storage stability, and at 25 and 37 ℃ to evaluate the transport stability. According to GB 4789.40—2016, samples were distributed to participating laboratories with operation instruction, and then the feedback result were analyzed. Results The identified result of all the related strains were correct and consistent with expectations. The result of uniformity and stability tests met relevant requirements. All of the experiment result submitted by 25 laboratories within the required time were correct, and the satisfaction rate was 100%. Conclusion The samples of Cronobacter spp. Enterobacter sakazakii in milk powder proficiency test can meet the relevant requirements, and this proficiency test provides external quality control assessment result for the participating labratories simultaneously.

Abstract:Objective To satisfy the demands of laboratory quality control and proficiency testing for the detection of enteroinvasive Escherichia coli (EIEC), a stable EIEC reference material was developed with independent intellectual property rights, good stability and clear background genomic information. Methods NGS Technique was used to sequence the whole genome of enteroinvasive Escherichia coli (CMCC 44840), bioinformatics analysis was performed to identify the species, serotype, MLST type and virulence genes; EIEC lyophilized samples with 10³ CFU were prepared by freeze-drying method ; The homogeneity test was performed according to CNAS-GL017, and the result were statistically analyzed by one-way ANOVA; The samples were stored at -20,4, 25 and 37 ℃, respectively, and their storage stability and transport stability were evaluated; Five kinds of food matrix samples were used to verify the applicability of reference materials, and three laboratories were organized for collaborative calibration. Results The genome size of CMCC 44840 was 4.96 Mb, the GC content was 50.7%, and the genome contained 5424 coding genes. This strain was identified as the species of Escherichia coli, and the serotype and the MLST type were predicted to be O28ac:H7 and ST311, respectively, and it carried ipaH, virB, virF and other virulence genes. The homogeneity test result of the EIEC lyophilized sample was F=1.79, which met the homogeneity requirements of reference materials. The EIEC samples were still 10³ CFU when storing at -20 ℃ and 4 ℃ for 60 d and storing at 25 ℃ and 4 ℃ for 7 d, and decreased on the third day at 37 ℃. EIEC were detected in 20 different food matrix samples with EIEC lyophilized samples after enrichment. The samples were 10³ CFU determined by three collaborative calibration laboratories, and there were no significant differences among these laboratories (F=0.59). Conclusion The EIEC reference material prepared in this study has clear genome sequence information. The homogeneity and stability meet the requirements and have good applicability, which can meet the requirements of quality control and capability verification in food testing laboratory.

Abstract:Objective In order to collect and analyze the suggestions and opinions in re-evaluation for the food additive standard system of China, and provide references for the revisions of the standards. Methods Feedbacks were collected through the “National Food Safety Standard Track and Re-evaluation Platform” from all aspects of GB 2760—2014, including product standards, labeling standards and production specifications. The rationality and feasibility of the opinions and suggestions were analyzed, and suggestions are proposed for standard revisions. Results This study collected about 207 opinions and suggestions through the platform from 2019 to 2020, mainly focusing on the application of GB 2760 and the content of product quality specifications, and analyzed the rationality and feasibility of the opinions. Conclusion The tracking and re-evaluation of standard is an important means to understand the implementation effect of standard. The reasonable opinions from the tracking and re-evaluation of standard provide a reference for the revision of the standard, and at the same time, the high-quality completion of the tracking and re-evaluation could improve the pertinence and practicality of publicity and implementation of national food safety standard.

Abstract:Objective In order to reduce the risk of export, the current status of the maximum residue limits (MRLs) of pesticides in garlic at home and abroad were studied. And on this basis, the suggestions for improving the standards of pesticide residues of China in garlic were given. Methods Current and valid standards of pesticide MRLs in garlic from European Union (EU), International Codex Alimentarius Commission (CAC), Japan, South Korea and China were collected, compared and analyzed. Results There are 129 pesticide MRLs related to garlic in China, and the EU, Japan, South Korea and CAC standards have 510,252, 173 and 23 pesticide MRLs, respectively. There are 93,67, 56 and 18 pesticides in the EU, Japan, South Korea and CAC standards that are the same as those in China, respectively. Among them, 49,19,22 and 4 pesticides MRLs are lower than China, respectively. Conclusion Due to the different dietary structures and registered pesticides in different countries, China and the EU, CAC, Japan and South Korea have significant differences in the total number of pestcides and their MRLs. It is recommended to improve relevant standards in China based on the actual garlic production and dietary needs in China.

Abstract:The liver is a vital organ, which is responsible for digestion and detoxification. Traditional studies on hepatotoxicity of xenobiotics are relied on in vivo animal models for data collection, however, animal tests are time consuming and expensive, and sometimes fail to predict human toxicity. To follow “3R” principle (Replacement, Reduction, Refinement), more in vitro models have become more popular for the assessment of hepatotoxicity. This review presents a brief overview and comparison of some in vitro liver models, as well as prospects for future development.

Abstract:Fentanyl analogues are laboratory-synthesized strong opioids with high addictive properties, simple preparation and easy derivatization. Their introduction to the drug market has shown increasing smuggling and illicit abuse worldwide. In addition, the toxic dose of fentanyl analogues is small, which can cause high mortality and pose a serious threat to public health in various countries. In this regard, 21 fentanyl-related substances were controlled by the United Nations cumulative regulations in 2018, and the Chinese government implemented the whole class control of fentanyl-related substances in 2019 in order to deal with the risk and harm caused by the problem of eating and injecting drugs, and protect people’s physical and mental health. Based on the social harmfulness of fentanyl analogues, As new psychoactive substances like fentanyl are harmful, we reviewed their properties, abuse method, laboratory detection and on-site rapid detection method. The development of detection technology and method is also briefly prospected in order to provide technical reference for drug inspection research.

Abstract:Objective To prepare a vegetable matrix reference material with pesticide residues and organize a proficiency testing to assess the performance of domestic laboratories on the quantification of pesticide residues. Methods Through simulated field planting, chili sprayed with carbofuran and dimethomorph was used as raw materials to prepare chili matrix reference material with pesticide residues. After preparation, the related evaluation and proficiency testing were carried out. Assigned values were obtained from consensus values by robust analysis and the result were assessed using Z-scores. Results The reference material was assessed to be sufficiently homogeneous and stable (all P >0.05). A total of 155 laboratories, from 30 regions in China participated the proficiency testing, while 142 (91.6%), 5 (3.2%) and 8 (5.2%) laboratories had acceptable performance (|z|≤2.0), warning signal (2.0<|z|<3.0), and unacceptable performance (|z|≥3.0), respectively. Conclusion A chili matrix reference material with pesticide residues was successfully prepared for proficiency testing and the result indicated that most of domestic laboratories had acceptable capability of pesticides quantification in vegetables.