Abstract:Objective The aim of this study was to determine the effects of dietary fatty acids on hepatic and blood fatty acid profile and metabolic associated genes in obese mice. Methods Eight-week-old male C57BL/6 mice were randomly divided into 7 groups with 10 cases in each group including control group, long-chain saturated fatty acid (LCSFA) group, medium-chain saturated fatty acid (MCSFA) group, n-3 polyunsaturated fatty acid (n-3 PUFA) group, n-6 polyunsaturated fatty acid (n-6 PUFA) group, monounsaturated fatty acid (MUFA) group and trans fatty acid (TFA) group, fed with normal-fat diet (providing 10% of total energy), lard high-fat diet, coconut oil high-fat diet, linseed oil high-fat diet, soybean oil high-fat diet, olive oil high-fat diet and 8% hydrogenated soybean oil high-fat diet respectively for 16 weeks. The fat-to-energy ratio of high-fat diet was 45%. The total energy of all diets was the same. After being fasted for 12 hours, the mice were anesthetized and the liver tissues were collected. Fatty acids composition in liver and blood samples were analyzed by gas chromatography. Real-time polymerase chain reaction (PCR) were used to measure the expression of hepatic and blood fatty acid metabolic associated genes. Oil red O staining was carried out to assess the hepatic lipid accumulation. Results Compared with the control group, significant hepatic and blood lipid accumulation were observed in the LCSFA, MCSFA, n-6 PUFA, MUFA and TFA groups. The n-3 PUFA group had less hepatic and blood lipid accumulation. Compared with the control group, the contents of total PUFA and total n-6 PUFA in the LCSFA group were significantly increased. The levels of SFA and MUFA were significantly elevated in the MCSFA group. The levels of total n-3 PUFA and total PUFA in the hepatic and blood of n-3 PUFA group were significantly rise up, but the content of total MUFA was significantly decreased. The levels of total n-6 PUFA, total n-3 PUFA and total PUFA in the n-6 PUFA group were significantly increased, but the contents of saturated fatty acid (SFA) and total MUFA were significantly reduced. The content of MUFA was significantly elevated, but the content of total SFA in the MUFA group was significantly decreased. The C18∶1 n-9t (TFA) content in the TFA group was significantly increased(P＜0.05). The expression level of hepatic fatty acid metabolism gene sterol regulatory element-binding protein-1c (SREBP-1c) mRNA in the LCSFA and MCSFA groups were significantly higher than those in the control and n-6 PUFA groups(P＜0.05). Conclusion The fatty acids composition in mice liver and blood changed in accordance with dietary fatty acids pattern. Different types of high fatty acid diet could affect hepatic lipid metabolism and accumulation under obesity by regulating the expression of related genes.

Abstract:Objective To express the cashew nut allergen Ana o 2 and identify its immunological activity. MethodsAna o 2 gene was synthesized and inserted into the pET-28a(+) expression vector. The recombinant plasmid pET-28a-Ana o 2 was constructed and sequenced. The correct recombinant plasmid was transformed into Rosetta (DE3), and the recombinant Ana o 2 protein was expressed and purified. The purified recombinant protein was identified by mass spectrometry. The immunological activity of the recombinant Ana o 2 protein was evaluated by enzyme-linked immunosorbent assay(ELISA) and protein immunoblot(Western blot). Results As determined by sodium dodecylsulphate polyacrylamide gel electrophoresis(SDS-PAGE), the molecular weight of the recombinant protein was approximately 54 kD, which was consistent with the theoretical value. The recombinant protein was identified as Ana o 2 by mass spectrometry. ELISA result showed that the level of specific immunoglobulin E (sIgE) in cashew-allergic sera was significantly different from that in negative sera (t=2.44,P<0.05). Western blot result showed that recombinant Ana o 2 had good reactivity with cashew-allergic sera. Conclusion A recombinant expression vector of Ana o 2 had been successfully constructed. Recombinant Ana o 2, which was expressed by prokaryotic system, had good reactivity with cashew-allergic sera.

Abstract:Objective To find out the contamination, antimicrobial resistance, virulence gene distribution and genotyping of Vibrio parahaemolyticus in different kinds of marine products in Chengdu. Increase the basic data on the prevalence and risk assessment of foodborne Vibrio parahaemolyticus in Chengdu. Methods According to GB 4789.7-2013, suspected strains of Vibrio parahaemolyticus were isolated from different marine products and accurately identified by biochemical tests and 16S rDNA sequencing. The antimicrobial resistance test of the isolated strains was carried out by Kirby-Bauer disk diffusion method. Two virulence genes related to its pathogenicity were detected by polymerase chain reaction(PCR), and then the isolated strains were typed by multilocus sequence typing. Results A total of 104 strains of Vibrio parahaemolyticus were isolated from 380 seafood samples collected, with an overall detection rate of 27.4%.Antimicrobial resistance test showed that 97.1%(101/104) of the isolates had resistance, of which the drug resistance rate to ampicillin was the highest (95.2%,99/104). The harboring rate of trh gene among the isolated strains was 12.5%(13/104), and was 0.1%(1/104) for tdh gene. 104 isolates were divided into 38 ST types, of which ST1801, ST392 and ST413 were at high level. No epidemic clone group was found in the isolates. Conclusion There were differences in the contamination rate, antimicrobial resistance, and virulence genes distribution of Vibrio parahaemolyticus in different kinds of marine products, which might be related to the breeding environment and transportation conditions.

Abstract:Objective Identification and drug resistance of two stains of Yersinia aleksiciae (Ya) isolated from different foods were studied, which provided technical reserves for the isolation of the new Yersinia spp. Methods A total of 300 food samples were collected from August 2018 to March 2019, including pork, beef and chicken. Separation culture, biochemical identification, drug resistance test, and whole genome sequencing analysis were performed on the isolated suspected Ya. Results The positive rate of Ya in food samples was 0.7% (2/300). In biochemical identification, Ya was distinguished from Yersinia enterocolitica (Ye) by lysine decarboxylase test, and Ya was positive for lysine decarboxylase while Ye was negative. Ya didn't exhibit natural resistance to ampicillin, cephalosporin I, ticarcillin and other drugs similar to Ye, and the drug resistance was different between the two strains. 16S rRNA, gyrB, rpoD genes were compared by whole genome sequencing to confirm that the two isolates were Ya. Conclusion The two strains of Ya were isolated and found in China for the first time. There was also no report on the isolation of these strains from food. The method provided in this study could be used for the isolation and identification of new Yersinia spp.

Abstract:Objective A method for the determination of 214 pesticide residues in green vegetables by QuEChERS using ultra high performance liquid chromatography coupled with quadrupole time of flight mass spectrometry was established. Methods After extracted by acetonitrile, the green vegetables were cleaned-up by a mixed sorbent with primary secondary amine (PSA), C18, Na₂SO₄ and graphitized carbon black (GCB). The target compounds were separated by Waters ACQUITY UPLC BEH C₁₈ column (2.1 mm×100 mm, 1.7 μm) using 5 mmol/L ammonium formate solution (0.1% formic acid) and acetonitrile as mobile phase by gradient elution, and analyzed in positive electrospray ionization mode by time of flight mass spectrometry (TOF-MS) scan-information dependent acquisition (IDA)-product ion scan. Results All the 214 pesticides showed good linear relationships in the range of 4-1 000 ng/L, and the correlation coefficients(r²)were higher than 0.99. The recoveries at three different spiked levels for all target compounds in blank matrices were 41.9%-128.5%, and the relative standard deviations (RSD) were 0.4%-14.3%(n=6). The limits of detection and quantitation of the method were 0.004-5.443 and 0.206-18.125 μg/kg, respectively. Eight pesticide residues were detected in the real samples. Conclusion The method was suitable for rapid screening and analysis of pesticide residues in green vegetables with the advantages of accuracy, rapidity, simplicity, high sensitivity and high throughput.

Abstract:Objective To develop a method for the determination of 23 pesticides in vegetables by atmospheric pressure gas chromatography-tandem mass spectrometry (APGC-MS/MS). Methods Acetone was used to extract target compounds in vegetable samples, while multi-walled carbon nanotubes was used as purifying material. The extracts were separated by DB-5MS column(30 m×0.25 mm, 0.25 μm). APGC-MS/MS was operated in positive ion multiple reaction monitoring mode (MRM) for pesticides detection. External standard calibration method was used for quantification. Results The 23 pesticides showed good linearity in the range of 0.01-20 μg/L, with correlation coefficient (R²) above 0.99. The detection limits and quantification limits of 23 pesticide residues in vegetable substrates were 0.02-0.40 and 0.05-1.25 μg/kg, respectively. The recoveries were between 66.7%-110.7% with relative standard deviation (RSD)≤14.8%. ConclusionThe method had high sensitivity, reproductivity and specificity and was suitable for rapid detection of multiple pesticide residues in vegetables.

Abstract:Objective To develop a method for simultaneous determination of aflatoxins(AFs)and zearalenone (ZEN) in vegetable oil and cereal products by solid phase extraction column purification coupled with ultra-performance liquid chromatography tandem mass spectrometry(UPLC). Methods AFs and ZEN in vegetable oil were extracted by acetonitrile-water solution(90∶10,V∶V). AFs and ZEN in cereals were firstly extracted by acetonitrile-acetic acid-water solution(84∶1∶16,V∶V)and then extracted by dichloromethane/ethyl acetate(90∶10,V∶V),and the extracts were concentrated and reconstructed by acetonitrile-water solution(90∶10,V∶V).The extracts of vegetable oil /cereals were purified by C₁₈-Al₂O3 solid phase extraction column. AFs and ZEN were separated by UPLC with acetonitrile-water gradient elution in a CORTECSTM C₁₈ chromatography column (2.1 mm×100 mm,2.7 μm), and qualified/quantified by mass spectrometry with electron spray ionization multiple reaction monitoring mode with stable-isotope internal standard. Results The linearity of AFs and ZEN were 0.1-30.0 and 1.0-500.0 ng/ml,the limits of detection were 0.03 and 0.3 μg/kg,and the limits of quantification were 0.10 and 1.0 μg/kg,respectively. The average recoveries of AFs and ZEN for spiked samples was 68.3%-98.6% and 84.5%-108.0% with the relative standard deviation 4.6%-11.5% and 4.2%-9.0%(n=6),respectively. Several quality control material were analyzed to verified the accuracy of the method. 100 samples sold in Dalian markets were analyzed. Aflatoxin B₁ and ZEN was detected in peanut oil and corn oil samples with maximum contents 12.80 and 370.00 μg/kg, respectively. Conclusion The method had several advantages including accurate,simple and cost-effective,environment friendly and it was applicable to batch analysis of AF and ZEN in vegetable oil and cereal products.

Abstract:Objective An analytical method was established for the two carotenoid colorants, which had not been included in the monitoring. The interferences such as fat and protein were effectively excluded through the optimization of pretreatment and detection conditions. The method on simultaneous determination of canthaxanthin and xanthophyll in eggs was successfully developed. Methods The samples were extracted by a simple ultrasonic extraction procedure with n-hexane and cleaned up on a neutral alumina cartridge. The analytes was separated by C₃₀ column (4.6 mm×250 mm,5 μm) with acetonitrile:methyl tertiary butylether (8∶2,V/V, containing 0.1% butylated hydroxytoluene) and water solution as mobile phases in gradient model. Then the carotenoids were detected with DAD detector. Results Under optimizing chromatographic conditions, the linear of the method were 0.20-10.0 mg/L with r≥ 0.999 3. The recoveries of the method were 89.3%-102% with relative standard deviations (RSDs) of 2.2%-4.9%. The limits of detection were 0.02-0.08 mg/kg. Conclusion The method was convenient, accurate and sensitive, and it was suitable for the determination of canthaxanthin and xanthophyll in egg samples.

Abstract:Objective For implementation of labeling regulations, an event-specific real-time polymerase chain reaction (PCR) method for quantitative detection of sugarbeet GTSB77 was established. Methods The specific primer pairs and probe based on the 3'flanking sequence of GTSB77 were designed. The specificity, sensitivity and repeatability of the developed method were examined, respectively. Results The specificity test showed it specific for GTSB77 detection. The limit of quantification(LOQ)was 16 copies and the amplification efficiency was 102%. Reapeatability of the established method was assessed and the relative standard deviation(RSD) ranged from 0.21%-1.66%. Conclusion This event-specific real-time PCR method is suitable for identification of GTSB77.

Abstract:Objective To explain and conclude a feasible food safety evaluation index system. Methods Totally 237 original literatures were collected based on the Web of Science database, and an index-based food safety supervision evaluation model was constructed by extracting free nodes and extracting tree nodes with NVivo11.0 software, and the logicality and reliability of the model were verified by regression to reality. Results Food safety is the common responsibility of government, enterprise and society. Conclusion Food safety supervision needs the positive interaction of government, food enterprises, consumers, media, industry associations and private testing institutions.

Abstract:This paper analyzes the driving factors and constructive measures of collaborative governance of food safety in Canada, and finds that it has relatively perfect measures on establishing the internal cooperation mechanism of the government, emphasize the autonomous ability of the industry associations and strengthening the international partnership, which effectively improves the Canadian food safety level. It is suggested that China could further promote the construction of food safety governance system by improving inter-governmental coordination, transforming the government's support for industry associations and promoting international regulatory cooperation.

Abstract:Objective To investigate the current status of allergen claims in the label of prepackaged foods in China, and to provide suggestions for the revision of the General Rules for the Labelling of Prepackaged Foods. Methods Sampling or photographing was performed in large and medium-sized supermarkets across the country, allergen claims information on pre-packaged food were collected, various food allergen claims were analyzed. Results A total of 8 694 samples were included. The overall identification rate of allergen claims was 21.58%(1 876/8 694). The percentage of foods containing allergens claims in bakery foods was the highest(65.73%, 468/712). Among the allergens, the highest rate of claims was milk and dairy (17.09%,1 486/8 694). The most frequent claims were “may contain”, “this streamline also produces”, “this processing equipment also produces”, and “this plant also processes” which indicated the presence of cross-contaminations, and those claims were mainly in bakery foods, puffed foods, grains and their products. Conclusion There were many types of food allergens in pre-packaged foods in China. The use of allergen claim was not standardized, and their were too many cross-contamination claims. In general, allergen claims were widely used in food products and should become the focus of allergens management in China.

Abstract:Objective To investigate the contamination situation of Salmonella at different times, slaughtering and processing sites in a broiler slaughter factory to acquire the key contamination point. Methods Chicken anal swabs, carcasses and broiler samples in different slaughtering stages were timely collected in a broiler slaughterhouse in Shaanxi Province from November 2016 to November 2017, Salmonella concentration was quantitatively detected by most probable number (MPN) method, Salmonella isolate recovered from positive samples were identified by polymerase chain reaction (PCR) combined with serum agglutination techniques. Results Among the 284 samples, 67 (23.6%) were positive to Salmonella, the average MPN value was 0.051 6 MPN/g. During sampling period, samples in July was the most frequently contaminated with the positive rate of 37.8%(14/37) and average MPN value of 0.064 7 MPN/g. the lowest Salmonella contamination rate was detected in November 2016 (13.9%,5/36) with average MPN value of 0.043 6 MPN/g. Among different processing stages, the highest positive rate was detected after scalding and fading (43.3%,26/60), the average MPN value of which was 0.060 5 MPN/g. The positive rate of chicken breast before freezing was the lowest (18.3%,11/60), and the average MPN value was 0.036 8 MPN/g, which was slightly higher than that of the whole chicken carcass/chicken breast collected from distribution and storage processes (0.035 8 MPN/g). Conclusion The result showed detection rate and MPN values of Salmonella positive samples in broiler slaughtering process had a strong seasonality, detection of Salmonella in different slaughtering stages indicated that vertical and cross-contamination might happen during the whole process. It was necessary to strengthen the regulation of broilers processing as well as the critical control points.

Abstract:Objective To study the epidemiologic and etiologic characteristics of Salmonella, Shigella, Vibrio parahemolyticus, diarrheagenic Escherichia coli(DEC) from foodborne diarrhea patients in Baiyin. Methods Stool samples were collected from foodborne disease patients in Baiyin during 2016-2018 and pathogenic bacteria strains were isolated and identified by biochemical characteristics, serotyping, drug resistance test and pulsed-field gel electrophoresis (PFGE). Results A total of 300 strains were isolated from 1 003 stool samples, the overall positive rate was 29.9% and the positive rate of DEC was the highest (29.1%, 292/1 003), followed by that of Salmonella and Shigella, and Vibrio parahemolyticus were not detected. Totally 1 003 foodborne disease cases were reported and the ratio of male and female was 1.3∶1, the detection rate of pathogenic bacteria in female patients(31.8%,136/428) was higher than male patients (28.5%,164/575),the patients were mainly adults aged 19-59 years and young children under 5 years old, and the positive rate was 31.5%(76/241)and 30.6%(188/615).Pathogenic bacteria strains were isolated mainly in the second and third quarter of the year. PFGE result indicated that 7 isolates belonged to 6 types, and there was one aggregation phenomenon. Salmonella had high resistant rate to tetracycline (85.7%, 6/7), it was found that 6 strains were multi-drug resistant. Shigella flexneri 2a subtype was resistant to 7 drug. 292 strains of DEC were sensitive to imipenem, and the drug sensitive rates of ceftazidime, cefoxitin, chloramphenicol and ciprofloxacin were greater than 80%, the resistance rate to ampicillin was the highest(80.8%,236/292), the multi-resistance to three or more antibiotics was 75.3%(220/292). Conclusion In the active etiological surveillance for foodborne diseases in Baiyin during 2016-2018, the detection rate of DEC was the highest. Pathogenic bacteria strains were isolated mainly in adults aged 19-59 years. The season specific characteristics of pathogenic bacteria was observed, and the infections mainly occurred in the second and third season. Multidrug resistance of pathogenic bacteria strains was serious with broad-spectrum.

Abstract:Objective To elucidate the prevalence of Listeria monocytogenes in Chinese salads in Shanghai, and to explore measures that can avoid cross-contamination and reduce the risk of infection caused by L.monocytogenes in salads. Methods Health risk and the influencing factors were estimated using a swift quantitative microbiological risk assessment (sQMRA) method with the prevalence of L.monocytogenes in Chinese salads collected from retail market in Shanghai, dietary consumption data and experimental data. Results The detection rate of L.monocytogenes in retail salads in Shanghai was 3.97%(6/151), the average concentration in contaminated samples was 60.53 CFU/g. For sensitive and non-sensitive people,the estimated incidence of nine different scenarios were 2.36×10-4-3.49×10-4 and 2.36×10-6-3.49×10-6, respectively, and the estimated cases were 162-431 and 6-17. Containers of different materials had different influence on the cross-contamination parameters of L.monocytogenes. The cross-contamination of the glass container was relatively high, and the estimated cases were the lowest. The cross-contamination parameters and ingestion of the ceramic containers were both low, and the estimated cases were the highest. After washing with sterile water or cleanser essence of the glass container and ceramic container, the estimated cases of L.monocytogenes infection were significantly reduced. Conclusion There was a certain risk of the contamination of L.monocytogenes in Chinese salads in Shanghai. Using glass containers and adopting cleaning measures could significantly reduce the number of cases of L.monocytogenes infection caused by cross-contamination during the preparation of Chinese salads in the kitchen.

Abstract:Objective This research was to conduct quantitative microbial risk ranking of Vibrio parahaemolyticus (VP) in different categories of seafood using swift quantitative microbiological risk assessment 2(sQMRA2)and to evaluate the impact of predictive model on the risk ranking result. Methods Based on the monitoring data of pathogenic microorganisms in seafood, the dietary consumption data, and parameters for storage, cross-contamination and cooking habits obtained from expert consultation in Dalian City in 2017, a deterministic quantitative risk ranking was conducted for different seafood-pathogenic VP combinations using sQMRA2 tool. Besides, the tool was improved by applying specific predictive models for different combinations to evaluate its influence on the final result. Results Shrimp-pathogenic VP combination had the highest per serving risk (1.2×10-5) and lead to the highest number of cases (5 000) among all the combinations. Predictive model had influence on the risk ranking result of the sQMRA2 tool. Conclusion Shrimp was the high-risk seafood leading to the incidence of VP in Dalian City from June to September in 2017. Avoiding cross contamination was the key to reduce the risk of VP in seafood. It was necessary to pay attention to the impact of predictive model on the result of risk ranking tool.

Abstract:Objective To evaluate the dynamic changes of residue level of malachite green (MG) and nitrofurans, including relevant metabolites, in turbot, snakehead fish and Chinese perch (i.e., “two types of prohibited veterinary drug abused in three kinds of fishes” issue) in Shanghai from 2008 to 2018, and to conduct dietary risk assessments of Shanghai residents. Methods Based on risk monitoring project from 2008 to 2018, a margin of exposure (MOE) approach was applied to evaluate human health risk according to the daily food consumption investigation of local residents. Results The average unqualified rate of two types of prohibited drugs abused in three kinds of fish was 19.0%(148/779) in the past 11 years, which fluctuated in a downward trend. The unqualified rate dropped from 33.7%(30/89) in 2008 to 3.6%(2/55)in 2018 with a 89.3 % declining range. In terms of different fish species, the unqualified rates of MG and nitrofurans in turbot, snakehead fish and Chinese perch were 42.6%(100/235), 8.6%(21/244) and 9.0%(27/300), respectively. Nitrofuran abuse problem (17.8%,139/779) outweighed that of MG (1.2%,9/779) in the past 11 years. The chronic risks of dietary intake of MG and nitrofurans from fishes were classified at very low level (MOE>10⁴), of which MOE were 1.7×10⁶ and 1.6×10⁶, respectively. Conclusion The malachite green and nitrofurans abuse in three kinds of fish Shanghai was improved in general. Shanghai residents did not face a possible chronic health risk either from MG or nitrofurans in fishes; however, authorities should continuously keep tight supervision and control of the MG and nitrofurans as prohibited veterinary drugs.

Abstract:Objective To provide suggestions for revising the national soy sauce standards and improving the industry management level through the analytical study of the national and international soy sauce related standards and regulations. Methods Standards and regulations related to soy sauce in countries such as Japan, South Korean, Singapore, India and Malaysia were collected and compared in terms of product quality indexes, contaminants and mycotoxins indexes as well as microbiological limits. Results The requests of product quality indexes, contaminants and mycotoxins indexes as well as microbiological limits in domestic soy sauce standards are not lower than that in international standards. The Japanese soy sauce standard has the most detailed request on raw materials and processes, and the test method presented makes the quantization of color possible. Conclusion The specific request in standard and the way of Japanese Agriculture Standard(JAS) certification in Japan may contribute to the high-quality soy sauce products, from which China can learn.

Abstract:Objective To investigate a foodborne disease outbreak in a small restaurant, analyze its causes and risk factors, and propose the measures for prevention and control. Methods Using field epidemiology survey to describe the features and analyze the risk factors of the incident. The strains homology was evaluated by pulsed field gel electrophoresis (PFGE). Results The major clinic manifestations of 5 cases were diarrhea and abdominal pain. Dietary survey showed that suspicious food was pot-stewed chicken leg at dinner on June 13,2019. The result of field hygienic survey indicated that the risk factor of the incident was the long placement time of the pot-stewed chicken leg at normal temperature status and insufficient re-heating time before dinner. Enterococcus faecalis was isolated from 3 anal swabs of cases, the pot-stewed chicken leg and the cutting board swab which sampled in the kitchen, and the strains were 100% homological. Conclusion The outbreak was caused by eating the pot-stewed chicken leg which was contaminated by abundant Enterococcus faecalis. It was suggested to strengthen the food safety awareness of small restaurant employees and the proper cooking method should be mastered.

Abstract:Over the last two decades, Salmonella 1,[5],12∶i∶- has been frequently detected in many countries or regions around the world, and nowadays it has become one of the major serotypes responsible for human infectious diarrhea. The etiology and genetic features of Salmonella 1,[5],12∶i∶- is quite similar with Salmonella Typhimurium(1,4,[5],12∶i∶1,2) but lacking the second phase flagellar antigen. It has evolved from Salmonella Typhimurium through multiple independent events involving different clonal groups or multiple clones. In this study, we reviews the epidemic characteristics including human infections, animal and animal-derived foods of Salmonella 1,[5],12∶i∶-, providing support for the prevention and control of infection and scientific researches.