Abstract:To investigate the prevalence and characteristics of ciprofloxacin and cefotaxime co-resistant Salmonella isolates in broiler flocks.Methods Ciprofloxacin and cefotaxime co-resistant Salmonella isolates were selected from isolates recovered from cloaca or rectal swabs and environment samples collected from 4 different districts in Henan Province. Ciprofloxacin and cefotaxime co-resistant Salmonella isolates were subjected to antimicrobial susceptibility testing, phylogenetic analysis and further characterized by screening for β-lactamase genes and quinolone resistance determinants by PCR and followed by DNA sequence analysis. Results Totally, five ciprofloxacin and cefotaxime co-resistant Salmonella isolates were recovered from 52 isolates, which all belonged to Salmonella Indiana. There were two antimicrobial resistant profiles which were AMP-CAZ-CHL-CIP-CTX-GEN (n=1) and AMP-CAZ-CHL-CIP-CTX-GEN-SXT-TET (n=4). Point mutations in topoismerase encoded genes gyrA and parC were identified, and all isolates carried plasmid-mediated quinolone resistance genes, including oqxAB and aac(6′)-Ib-cr, but qnrA, qnrB, qnrS, qnrC, qnrD and qepA were not detected. All of the five cefotaxime-resistant Salmonella were due to the production of plasmid borne blaCTX-M-65.Conclusion The extensive prevalence, complicated quinolone resistance mechanisms of isolates and the possible transmission of blaCTX-M-65 were existed in broiler flocks and environment. In order to clarify the farm-table-patient resistant relevance chain of infection transmission and to provide a scientific basis for antibiotic medication in clinical, the continuous surveillance of multidrug-resistant Salmonella in broiler flocks should be carried out.

Abstract:Clostridium was isolated and characterized from powdered infant formula (PIF), whey protein concentrate (WPC) suspected to be contaminated with C.botulinum and WPC-based products, as well as PIF collected from Beijing market.Methods Clostridium isolates were characterized by morphological characteristics, gram′s stain, microscopic and electron microscopy characteristics, biochemical test, 16S rRNA sequencing and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry(MALDI-TOF-MS) methods.Results Among 78 samples, 16(20.5%, including 2 WPC and 14 PIF) samples were contaminated with Clostridium. A total of 17 isolates were obtained, of which 12 isolates were identified as C.sporogenes, 2 isolates of C.beijerinckii, 2 isolates of C.butyricum and 1 isolate of C.tertium.Conclusion WPC imported from New Zealandand WPC-based PIF were heavily contaminated by Clostridium, and the most predominant species of Clostridium detected was C.sporogenes.

Abstract:To understand the status of foodborne Bacillus cereus virulence genes in Honghe prefecture.Methods Ten virulence genes of Bacillus cereus which were collected from Jan 2011 to Sep 2014 in Honghe prefecture were detected by polymerase chain reaction. Results The strains of Bacillus cereus generally carried enterotoxin gene. All of the strains carried at least one enterotoxin gene. Only one strains carried emetic toxin gene.Conclusion Foodborne Bacillus cereus in Honghe prefecture might have strong pathogenicity, posing a potential food safety and public health threat.

Abstract:To acquire original data of Salmonella serotype distribution during pig and poultry slaughter processes in Shandong Province, and to provide data for the risk assessment of animal products.Methods Salmonella was isolated from slaughterhouses in Shandong Province from September to December 2014. xMAP Salmonella serotyping assay kit was used to detect the genes of somatic O antigen, motility H antigen and additional target (AT) gene. Salmonella serotypes were identified by xMAP Salmonella serotyping assay software throught gene information. Results A total of 299 Salmonella isolates were divided into 29 serotypes and 36 isolates could not be typed. S.Derby (24.8%,83/335) and S.Enteritidis (15.2%,51/335) were the major serotypes in pig and poultry slaughter processes in Shandong Province. S.Derby, S.Thompson and S.Agona were detected both in pig and poultry slaughter processes; S.Derby (39.8%,64/161), S.typhimurium (19.3%,31/161) and S.Thompson(13.7%,22/161) were themajor serotypes in pig slaughter process; S.enteritidis (28.7%, 50/174), S.Indiana (12.1%, 21/174) and S.Derby (10.9%, 19/174) were the major serotypes in poultry slaughter process. Salmonella serotypes varied in various areas of Shandong Province. In the pig slaughter processes, S.Derby was the major serotype except the middle of Shandong Province; In the poultry slaughterhouses, S.enteritidis was the major serotype in the east and west of Shandong Province, S.Derby was the leading serotype in the northeast; S.Thompson was the most prevalent in the middle of Shandong Province.Conclusion There were various Salmonella serotypes at slaughterhouses in Shandong Province, and slaughter processes supervision and control should be strengthened to decrease the risk of Salmonella contamination in animal products.

Abstract:To analyze the pattern and characteristics of the foodborne disease incidence in Baoshan, Yunnan Province from 2010-2013 and provide the scientific basis to make the preventive and control measures of food poisoning.Methods Descriptive epidemiological method was used to analyze the surveillance data of foodborne disease in Baoshan from 2010-2013.Results A total of 25 outbreaks of food-borne disease were reported, of which, one was verified as foodborne parasitic diseases, and the others were food poisoning. The outbreak caused 439 reported patients and 4 deaths. Food poisoning occurred mainly in the second and the third quarter.Conclusion We should popularize the health and safety knowledge to the public, and enhance the supervision and management of school dining hall and other key places.

Abstract:To establish a multiplex real-time fluorescence RT-PCR detection method of norovirus GI, GII and hepatitis A virus in strawberry, and apply to actual sample.Methods After pretreatment of strawberry samples, viruses were concentrated, extracted and purified for virus RNA. The samples were determined by real-time fluorescence RT-PCR and multiplex real-time fluorescence RT-PCR. The specificity, sensitivity, and practical applications of the methods were also analyzed. Results The nucleic acid extraction method could effectively remove the inhibitory factors. The methods showed high specificity with no cross amplifications of other virus. The detection limit of multiplex real-time fluorescence PCR for norovirus GI, GII and hepatitis in strawberry was 56.2 RT-PCR₅₀/20 g, 31.6 RT-PCR₅₀/20 g and 31.4 CCID₅₀/20 g, respectively. According to the test results of 50 inspection samples, the results were all negative.Conclusion The established system of nucleic acid extraction and real-time fluorescence RT-PCR detection method is suitable for the simultaneous detection of norovirus GI, GII and hepatitis A virus in strawberry.

Abstract:To develop a new method for rapid determination of alpha solanine in potatoes. Methods The homogenized potato sample was eluted with 5% acetic acid aqueous solution for 30 min, and it was then extracted by isobutanol. The extraction solution was evaporated by nitrogen. Subsequently the residue was redissolved in methanol and analyzed by HPLC after filtration. Separation was obtained by Discovery C₁₈ column(150 mm×4.6 mm, 5 μm)and mobile phase of acetonitrile-0.02 mol/L potassium dihydrogen phosphate (22∶78, V/V) with flow rate of 1.0 ml/min. The detection wavelength was set at 210 nm and the temperature was 30 ℃. Results Good linearity was obtained for alpha solanine within the range of 0.02-1.00 mg/ml, and the r was 0.999 7. The limit of detection(S/N=3)and the limit of quantification(S/N=10)were 0.68 and 2.27 μg/ml. The average recoveries of different concentration levels were between 98% and 116%. The relative standard deviations (RSDs) ranged from 0.16% to 1.79%.Conclusion This method is fast, simple, precise and it is feasible for the determination of alpha solanine in potatoes.

Abstract:To establish an accurate, reliable and stable method for determination of total arsenic in food.Methods Fish, seaweed (GBW 10023-GSB-14), rice (GBW 10010) and chicken (GBW 10018) were selected as food samples, which were pretreated by wet digestion, microwave digestion and dry ashing respectively, and determined by hydride generation atomic fluorescence spectrometry. Results The total arsenic results of dry ashing were 3.18±0.052,7.01±0.063,0.104±0.002 and 0.115±0.004 mg/kg which were in the range of reference values. The recovery rates were 93.7%-98.5%, and the RSD was below 2.31%. The results of wet digestion were 3.12±0.041,6.93±0.072,0.103±0.003 and 0.112±0.003 mg/kg which were in the reference range. The recovery rates were 89.2%-97.5%, and the RSD was below 1.92%. The results of fish and seaweed with microwave digestion were 1.74±0.032 and 15.40±0.096 mg/kg, which were less than 60% of the reference value, but the results of rice and chicken were 0.102±0.001,0.114±0.005 mg/kg, both in the reference range. The recovery rates were 96.3%-97.5%, and the RSD was below 2.51%. Wet digestion could be applied to most of the food samples for its flexibility in digestion temperature, time, type and dosage of acid. Microwave digestion consumed less time but large amount of acid, which could be applied to the relatively simple samples. Dry ashing method was suitable for samples of high volatile temperature, high oil content and complex arsenic structure because of its time-consuming.Conclusion Wet digestion and dry ashing could be applied as the pre-treatment of most food samples. Microwave digestion method has its limitations, only suitable for samples of arsenic with relatively simple morphology.

Abstract:Establishment of real time fluorescence single primer isothermal amplification method for detection of Cronobacter sakazakii.Methods Taking Cronobacter sakazakii OmpA gene specific sequence as the target sequence, the RNA-DNA combination primer and chain termination sequence was designed, and the reaction system was optimized. 4 different strains of Cronobacter sakazakii strains and 21 other foodborne pathogens were detected by the method, and the specificity of the real-time fluorescent SPIA was analyzed.The sensitivity was analyzed by different dilution of Cronobacter sakazakii and the detection limit was determined by spiked infant formula. Results Only Cronobacter sakazakii could be detected and showed the typical fluorescence curve. The method has good specificity. In 40 min, the sensitivity of real-time fluorescent SPIA for the detection of Cronobacter sakazakii in pure culture was 1 copies/reaction. The corresponding number of the living bacteria was 1.6×10-1 cfu/ml. The detection limit of Cronobacter sakazakii in infant formula is 1.5×10⁰ cfu/100 g.Conclusion The method has the advantages of high sensitivity, strong specificity, less time-consuming.

Abstract:To establish a method for determination of 6 zeranols residues in animal derived foods by liquid chromatography-tandem mass spectrometry with isotope dilution.Methods The sample was added isotope internal standard and extracted using methanol. Methanol was nearly dried-up under nitrogen and the residue was dissolved with ethyl acetate. After solid phase extraction of amino cartridge, the eluent was dried-up by nitrogen at 50 ℃. The analytes were dissolved by the mobile phase and determined by liquid chromatography-tandem mass spectrometry. Results The recoveries of analytes were 84.8%-103.6%, and the relative standard deviations of detection were 3.7%-8.6%. The limits of detection and quantification were 0.03-0.07 μg/kg and 0.10-0.24 μg/kg.Conclusion The method is sensitive, accurate and it can meet the determination requirements of 6 zeranols residues in animal derived foods.

Abstract:A method of pre-column derivatization ultra-performance liquid chromatography with fluorescence detector was developed for simultaneous determination of aflatoxins (AFB₁, AFB₂, AFG₁ and AFG₂) in beers.Methods The aflatoxins were extracted from beer samples by acetonitrile and cleaned up with multifunctional purification column to remove the matrix interference. The purified solution was concentrated and dried with nitrogen. After derivatized by trifluoroacetic acid, the aflatoxins were separated by reverse liquid chromatography (T3) with gradient elution and detected by fluorescence detector (FLD). Results The linear ranges of each compound were wide, and relative coefficients were between 0.999 2 and 0.999 6. The recoveries were within 90.47%-108.17%, and the relative standard deviations (RSDs) were between 0.97%-8.13%. The limits of detected (LODs) of 4 aflatoxins were 0.05,0.02,0.08 and 0.02 μg/kg in beers, respectively.Conclusion The established method was sensitive, selective, accurate and simple for the simultaneous determination of aflatoxins in beers.

Abstract:The method was established for the determination of 17 kinds of plasticizer (PAEs, incluiding DINP) in edible vegetable oils by solid phase extraction and gas chromatography mass spectrometry.Methods The PAEs in the oil samples were extracted by acetonitrile saturated with n-hexane, further purified with special solid phase extraction column, and eluted with acetone. The eluting solvent was then collected, concentrated, and directly detected with gas-chromatography spectrometry (GC-MS). Results The linearity of PAEs was good. The detection limits of 17 PAEs were 0.01-0.5 mg/kg. The recoveries were 76.5%-105.2% in low, medium and high level spiked samples. The relative standard deviations were less than 8.0% (n=6).Conclusion Compared with GB/T 21911-2008, this method was not only suitable for the detection of DINP, but also could effectively remove the interference of grease and pigment and significantly lower the detection limits. The method was simple, accurate, solvent saving and had good reproducibility.

Abstract:A method was developed for the rapid screening of maleic acid in starch matrix by electrospray ionization-ion mobility spectrometry (ESI-IMS).Methods The samples were extracted by ultrasound with 80% methanol and diluted with methanol, then the supernatant was filtered with 0.22 μm microporous membranes. The IMS was operated in the negative mode at ambient pressure using ESI as the ionization source and dry, clean air as drift gas and the analytes were quantified by the matrix-matched external method. Results The calibration curves showed good linearity within the range of 5-50 μg/ml with the correlation coefficients(r) of 0.998 3. The limits of detection (LODs) of maleic acid in starch matrix was 2 μg/ml, and the limit of quantification (LOQs) was 5 μg/ml. The average recoveries of maleic acid in starch matrix at three spiked levels (5.0,0.0,0.0 mg/L) were 87.5%-96.0% with the relative standard deviations (RSD) of 3.58%-7.07%.Conclusion The method is simple, rapid and feasible, and could be applied as a screening method for the analysis of maleic acid in starch sample.

Abstract:To establish a method for determination of 17 illegally added drugs in memory improving health food with the formulas of oral liquid, pills, soft capsule by high performance liquid chromatography.Methods Samples in different dosage formulas were extracted with 50% methanol by ultrasonic and cleaned up with C₁₈ SPE cartridges, then separated ona AnccliaimTM Mixed-Mode WCX-1 HPLC column with a mobile phase of 100 mmol/L sodium dihydrogen phosphate solution-acetonitrile for gradient elution, and quantified with external standard with photodiode array detector method. Results The calibration curves of the 17 chemical drugs with in appropriate concentration ranges showed a good linearity with high correlation coefficients. The average recoveries were from 85% to 120% with RSDs of 0.8%-4.8%.The detection limits of the 17 chemical drugs ranged from 10 to 40 μg/ml.Conclusion This method is simple, accurate and rapid. It could be used for simultaneous determination of 17 illegally added drugs in health food in the formulas of oral liquid, pills, soft capsule, and is suitable for confirming 17 illegally added drugs in memory improving health food.

Abstract:The purpose of this paper is to discuss the future development of the national food safety risk surveillance system according to the current situation and the existing problems in China. It's urgent to develop a basic theory to guide the surveillance, clarify the objective, improve the ability and strengthen the risk communication. It's important to optimize the work mechanism to improve surveillance ability of the technical institutions, ensure the effectiveness by updating working mode and using the social resources, and improve the national monitoring capability by technological innovation and data mining.

Abstract:To monitor and assess the residues of malachite green (MG) and its metabolites leucomalachite green (LMG) and nitrofuran metabolites in mandarinfish and snake head mullet of Guangdong Province.Methods The residues of MG and its metabolites LMG and nitrofuran metabolites in muscle were measured by high performance liquid chromatography tandem mass spectrometry (HPLC-MS). Results The total detection rate of MG was 11.7% in 2013, and the total detection rate of nitrofuran metabolites was 20% in 2013. The total detection rate of MG was 25% in 2014, and the total detection rate of nitrofuran metabolites was 12.5% in 2014. The MG residues ranged from 0.58 to 19.1 μg/kg in the past two years, and the nitrofuran metabolites residues ranged from 0.66 to 36.6 μg/kg. The exposure assessment showed that the average daily exposure of nitrofuran metabolite in body might be 0.34 μg, that is 0.005 μg/kg BW, the maximum exposure might be 0.87 μg, that is 0.01 μg/kg BW, the average daily exposure of furazolidone metabolite in body might be 0.56 μg, that is 0.009 μg/kg BW,the maximum exposure might be 2.10 μg, that is 0.03 μg/kg BW, the average daily exposure of malachite green might be 0.24 μg or 0.004 μg/kg BW, and the maximum exposure might be 1.10 μg or 0.02 μg/kg BW.Conclusion The detection rate of MG and nitrofuran metabolites in mandarinfish and snake head mullet was relatively low. Dietary assessment showed that the risk of malachite green exposure was minimal.

Abstract:The clean-up program of food standards started in 2012. About 5 000 food standards were collected, including 398 food codes of practice. A comprehensive overview of these standards were conducted. Some questions were discovered, for example the contents of codes of practice were not clearly defined, some important codes of practice need to be developed. This paper discussed the problems of the existing standards, analyzed the principles of establishing food codes of practice, and provided advices for the integration of food standards.

Abstract:To study the contamination of pathogenic bacteria in food and their resistance to antibiotics, and to find the dominant epidemic strains in Ningbo.Methods Direct separation and culture enrichment were both used for pathogen isolation. The identification of bacteria was performed by Vitek 2 compact and API method. Sub-typing of bacterial was performed by serology and PFGE. Antibiotics resistances were tested by Kirby-Bauer method. Antibiotic resistance genes were detected by PCR. Results 7 categories and 12 kinds of bacteria (2 331 strains) were detected from 6 812 food samples. Most of them were pathogenic Vibrio, the second prevalent was Salmonella, and the third was Aeromonas. Vibrio parahaemolyticus was the major epidemic foodborne pathogenic strain in Ningbo. The detection rate had significant difference (P<0.01) compared to other pathogens. 10 serum groups and 29 PFGE types were identified, in which O6 and O5 serum groups and type 1 of PFGE were the dominant epidemic. Pathogenic bacteria detected were sensitive to most antibiotics. There were three Aeromonas strains which were resistant to multi-drug with aacc genes. Conclusion Foodborne pathogenic bacteria in Ningbo were various. All categories of pathogenic bacteria had their dominant epidemic strains, while Vibrio parahaemolyticus was the major contributor of foodborne diseases. Serotype and PFGE typing of bacteria could be applied to find their dominant epidemic strains, but either of them had certain limitations. The broad-spectrum antibiotic treatment was effective for foodborne bacterial illness.

Abstract:To find out the content of thiocyanate in raw milk of Hebei Province. Methods Following the principles of representativeness, randomness and timeliness, 159 raw milk samples were collected from Hebei Province in 2013, including 100 samples from dairy farmers, 32 samples from milking workshop, 27 samples from milk tankers in a dairy plant. Thiocyanate were determined by ion chromatography refering to standard determination operating procedures of sodium thiocyanate in foods in National food contamination and harmful risk handbook. Results The content of 48 samples were below the detection limit, the maximum value was 6.45 mg/kg, P50 was 1.32 mg/kg, and P95 was 2.94 mg/kg.Conclusion Thiocyanate levels of 159 raw milk samples were lower than the values reported in the literature.

Abstract:To elucidate the contamination situation of deoxynivalenol (DON) and its derivatives in cereal and cereal-based products collected from Hebei region, 31 infant cereal food supplement, 112 oat and oat-based products and 293 wheat flour were investigated.Methods The samples were detected by liquid chromatography tandem mass spectrometry referred to the method of monitoring manual of chemical contaminants and harmful factors in food. Results 29 infant cereal food supplement samples were detected DON and the detection rate was 93.5%, 10 oat and oat-based products were detected DON and the detection rate was 8.9%, 292 wheat flour samples were detected DON and the detection rate was 99.7%. The serious contamination samples of DON in infant food supplement and oat-based products were contained wheat flour.Conclusion DON contamination in wheat flour was common. The maximum contamination level was 878.4 μg/kg, but all samples were below the national standards. Because there was no limit for DON in infant food supplement , the contamination was worthy of attention.

Abstract:To evaluate and rank the risk of chemical, pathogenic, viral, and parasitic hazards in food according to the massive data from food supervision and inspection, explore methods of risk ranking, and provide scientific basis to set administrative priorities. Methods Based on theories of food risk assessment, expert review, judgment by experience and Delphi's expert consultation were adopted in this study to establish methods of risk ranking. Results The methods of risk ranking for chemical and biological hazards in food were preliminary developed. Total risk score=8×health risk+2×influential factor. First level indicators of health risk were severity, possibility and vulnerability. First level indicators of influence factor were social influence, economic influence and supervision influence. Each first level indicator was the weighted sum of several second level indicators. This established method was used to rank food risks based on 30 000 data from food safety supervision and inspection system in Guangdong Province in 2013-2014.Conclusion The methods of risk ranking and its indicator system identified the rank and priority of food risk, laid scientific foundation for risks assessment, decision-making and resources allocating.

Abstract:To analyse the cadmium level in food and dietary intake of residents in Hangzhou for risk assessment.Methods The content of cadmium in foods were determined by the monitoring project of food contamination in Hangzhou city during 2011-2013. The actual dietary intake of cadmium was obtained by combining the data of food consumption survey in Hangzhou residents in 2010 with the data of cadmium content in foods. The dietary intake of cadmium among Hangzhou residents was assessed by provisional tolerable monthly intake (PTMI) recommended by JECFA. Results Cadmium was detected in 745 of 1 010 samples (73.76%) from ten food categories. Rice, wheat and pig viscera were all positive while the detection rate of dairy products was the lowest. The violation rate was 5.12%, mainly in rice, aquatic products, pig kidney, eggs, vegetables and edible mushrooms. Combined with the mean value of food consumption estimates, the cadmium exposure of Hangzhou residents from 10 major food categories were 22.61 μg/kg BW, which was below the PTMI (25 μg/kg BW), and the MOS value was 1.11. The highest contributor were rice(64.16%), vegetables (15.28%) and aquatic products (14.48%).Conclusion The average dietary exposure of cadmium from 10 food categories did not exceed the PTMI, the MOS was above 1, so the dietary cadmium exposure was safe in general, but more attention should be paid to the risk of cadmium exposure in higher food consumption population. Besides, based on the consumption of rice in Hangzhou and the high contribution rate of rice to dietary cadmium exposure, more attention should be paid to prevent and control cadmium contamination in the farmland.

Abstract:To find out the scale of the epidemic and the pathogenic source of a food poisoning incident at a kindergarten in Shenzhen, and provide recommendations for the prevention.Methods The cases were screened according to the case definition. The descriptive epidemiology was used to address epidemiologic characteristics and provide clue for etiology of the disease, while case-control study was used to analyze the risk factors. The food samples, vomitus, anal swabs and environment samples were collected for microbiological testing. The cognition of vendors and consumers to bitter Lagenaria siceria was investigated at the market. Results A total of 21 cases with clinical symptoms:vomiting (80.95%, 17/21),diarrhea (71.42%, 15/21), abdominal pain (61.90%, 13/21), dizziness (28.57%,6/21) and headache(14.29%,3/21) were found. The shortest, longest and median incubation period was 0.5,7.5,2.5 hours, respectively. The diet history of 42 control cases was investigated. Case-control study showed that the Lagenaria siceria was the suspicious food (OR=266.00,CI=14.15-5 000.00). Staphylococcus aureus, Bacillus cereus, Salmonella, Shigella, Vibrio parahaemolyticus and Proteus were not detected from 22 samples. In addition, the remaining lagenaria siceria tasted very bitter. Only 19.05% (4/21) of the vendors and 5.77% (3/52) of the residents knew that the bitter Lagenaria siceria could cause food poisoning.Conclusion The food poisoning incident was caused by bitter Lagenaria siceria. It was suggested childcare facilities should use other vegetables instead of Lagenaria siceria dishes and consumers should taste the Lagenaria siceria before buying it. At the same time the health sector should strengthen the health education of merchants and citizens to prevent the poisoning.

Abstract:In the past few years, high-resolution mass spectrometry techniques have shown great potential development in the field of pesticide residue analysis. This paper reviews the current state-of-art of two main high-resolution mass spectrometry techniques, time-of-flight mass spectrometry and FT Orbitrap-MS, applied to the analysis of pesticides in food-based matrices. This review briefly expounds the advantages of high-resolution mass spectrometry techniques and the prospective of its future application in the field of pesticide residue analysis.

Abstract:glucan, a well-known biological response modifier, plays an important role in triggering the function of dendritic cells (DC). There is evidence that binding of β-glucan to specific receptor in DC can induce their maturation, enhance the production of various cytokines, and regulate adaptive immune responses. β-glucan appears to be effective at enhancing immune function and reducing susceptibility to infection and cancer. This paper summarizes the current understanding of β-glucan as modulators of dendritic cells and their possible use as anti-tumor, anti-infection and anti-inflammation treatments.