Abstract:Objective To study the rapid identification of freezing-thawing meat by stoichiometry combined with low field nuclear magnetic resonance（LF-NMR）.Methods CPMG sequences were selected by LF-NMR to collect 111 NMR signals from pork tenderloin. Through the inversion of NMR signal data， four principal components were extracted from 12 variables by principal component analysis， and the discriminant research model was established.Results According to the analysis of fresh meat， slightly freezing-thawing meat and freezing-thawing meat， the accuracy of the model was 95.5% verified by back generation method， and it was 94.6% by cross-verification.Conclusion LF-NMR is simple and rapid， and can be used for discriminant analysis of freezing-thawing meat， which provides a reliable and effective basis for the supervision department.

Abstract:Objective To evaluate the physical fatigue relief function of ginseng compound formula beverage （ginseng compound） and explore its molecular mechanism.Methods Two hundred and fifty healthy male KM mice were divided into 5 groups with 50 mice in each group， including control group， sugar control group and 10 times concentrated beverage of ginseng compound groups： 4.16， 8.33 and 16.66 mL/kg·BW. After continuously gavage for 30 d， 20 mice for weight-bearing swimming test， and the remaining 30 mice in each group were randomly selected for blood lactic acid， liver glycogen and exhaustive swimming experiments， based on the exhaustion experiment （high-urea model） to carry out mechanism exploration， including the effects of test subjects on exhaustion exercise-induced injury， antioxidant pathway and mitochondrial autophagy pathway of quadriceps femoris muscle.Results Compared with the control group， mice in the ginseng compound group were more active， and the weight-bearing swimming time of mice in the 4.16 and 16.66 mL/kg·BW groups increased significantly （P<0.05）. The area integral of blood lactic acid decreased significantly in the three dose groups （P<0.05）. Blood urea nitrogen of 4.16 mL/kg·BW group in the exhaustion experiment decreased significantly （P<0.05）， Nrf2 transcript level in skeletal muscle， activities of superoxide dismutase and catalase increased significantly （P<0.05）， PINK1-Parkin transcript level decreased significantly （P<0.05）. Creatine kinase， lactate dehydrogenase and malonaldehyde in serum decreased significantly in the three dose groups （P<0.05）.Conclusion Ginseng compound has the effect of relieving physical fatigue， and its mechanism may be related to the reduction of skeletal muscle mitophagy caused by exhaustion through the Nrf2/ARE-PINK1-Parkin pathway.

Abstract:Objective To study and verify the sterilization conditions of brewed soy sauce， and finally obtain the sterilization procedures for brewed soy sauce.Methods After determinating of diluted Staphylococcus aureus， the remaining viable bacteria was counted after 80 ℃， 85 ℃， 90 ℃ treatment. And the D， Z and F value were calculated. After directly conducting heat penetration experiments on brewed soy sauce products， a reasonable sterilization procedure was finally obtained.Results The sterilization procedure was： D_{80 ℃}=6.13 min， r²=0.909 4； D_{85 ℃}=4.78 min， r²=0.901 0； D_{90 ℃}=1.53 min， r²=0.680 2； Z=16.6 ℃； F_{80 ℃}=36.78 min；F_{85 ℃}=28.68 min； F_{90 ℃}=9.18 min. After the theoretical calculation when the reference was 90 ℃， the best sterilization temperature and time were 90 ℃， 9.18 min. After verification of actual processing process， it was determined that the final sterilization procedure was： 36 min-4 min/90 ℃.Conclusion The main factor leading to the difference between theoretical calculation and actual processing process is that sterilization is a cumulative process， so in addition to theoretical calculations， verification is also particularly important in the actual application process.

Abstract:Objective The detection method of rapid analysis of chlorpyrifos and its degradation products in vegetables and fruits by HPLC-MS/MS was established.Methods Both chromatographic conditions and mass spectrometry conditions were optimized. Leek， celery， cabbage， apple and citrus were used as substrates for pretreatment by QuEChERS method， and the effects of PSA and GCB on chlorpyrifos and its degradation products were investigated. Finally， the method was investigated based on limits of detection， limits of quantification， linear range， matrix effect， accuracy and precision.Results The suitable mobile phase was acetonitrile and 0.1% （V/V） formic acid in water. Acquisition parameter of mass spectrometer was ESI⁺. 45 mg/5 mL of GCB in pretreatment was the best purification condition. The linearity of the four compounds was good （R²≥0.99）， and the limits of quantification （LQD） were 1-30 μg/kg. The average recoveries of three levels ranged from 66.1% to 113.6%， and the relative standard deviation （RSD） was 1.3%-16.9%.Conclusion The method is fast， efficient， accurate， repeatable and suitable for the confirmation and quantification of chlorpyrifos and its degradation products in vegetables and fruits.

Abstract:Objective Based on surface enhanced Raman spectroscopy technology， a rapid detection method for thiamethoxam in leaf vegetables was established.Methods Using gold nanoparticles as the reinforced base and carbon nanocages with porous structure as the purifying agent， the interference of pigment and organic acid in vegetable was effectively removed based on its large specific surface area and strong adsorption capacity.Results The limit of detection was 1 mg/kg. In the range of 0.5-15 mg/kg of thiamethoxam， the linear relationship was good. The recoveries ranged from 90.7% to 121.7% with relative standard deviation of 2.3%-7.5%.Conclusion This method has high sensitivity， simple and rapid operation， and it is suitable for the rapid determination of thiamethoxam residues in vegetables by grass-roots supervision departments.

Abstract:Objective A method of identification of Acanthopanax senticosus illegal addition in beverage and processed wine based on the diagnostic ratios of trace components was developed.Methods The high-performance liquid chromatography conditions to determine the characteristic components of Acanthopanax senticosus were optimized. Samples of Acanthopanax senticosus from different growing areas were tested and analyzed. The peak area ratios of protocatechuic acid， chlorogenic acid， Acanthopanax senticosus B and Acanthopanax senticosus E were compared and analyzed.Results The peak area ratios of Acanthopanax senticosus E and Acanthopanax senticosus B in the 3 matrix samples were constant and stable in a certain range， and it had good reproducibility. The diagnostic ratio was analyzed by box plots. It was determined that the diagnostic ratio discrimination interval of Acanthopanax senticosus was 1.19-2.71. The diagnostic ratio of health food containing Acanthopanax senticosus was consistent with this method.Conclusion The method is simple and efficient， which can be used to identify Acanthopanax senticosus illegally added in beverage and processed wine.

Abstract:Objective To establish an analytical method for simultaneous determination of 55 illegal addition of compounds in doet foods by ultra-performance liquid chromatography tandem mass spectrometry.Methods After ultrasonic extraction with methanol， the samples were separated on Agilent Eclipse Plus C₁₈ RRHD column （2.1 mm×100 mm， 1.8 μm） with gradient elution using a mobile phase of 0.1% formic acid aqueous solution and acetonitrile. Under positive and negative ion scanning conditions， dynamic multiple-reaction monitoring mode was used for monitoring.Results The 55 illegal addition of compounds showed good linear relationship in the corresponding linear range with all the correlation coefficient greater than 0.995. The average recoveries were 75%-125%， and the relative standard deviations were less than 12%， the LODs were all in the range of 0.02-1.25 μg/g. Fifty batches of samples were tested by this method. Fluoxetine， sibutramine， N-monodesmethyl sibutramine， N-didesmethyl sibutramine， bisacodyl， torasemide were detected in 38 samples.Conclusion This method is simple， rapid， sensitive， efficient and accurate， which can be widely applied in the high-throughput detection of illegally added chemicals in different kinds of diet foods matrices.

Abstract:Objective To develop a fast DNA release extraction reagent for foodborne pathogenic bacteria and optimize its application.Methods Orthogonal test was used to investigate the influence of Triton X-100（A）， SDS（B）， EDTA（C） and NP-40 （D）on the release effect. The influence of sample matrix on the release effect was determined by testing the actual sample with spiking standard， and the applicable process was further optimized.Results The optimal reagent combination was A1B2C2D2， which were Triton X-100 5.5%， SDS 0.04%， EDTA 2 mmol/L and NP-40 2%.Conclusion The reagent has a wide range of temperature adaptation with short time and high efficiency， which can be used for sample processing and nucleic acid extraction in poor experimental environment. It is convenient to use with low production cost and has application value for on-site quick inspection.

Abstract:Objective To explore the difference in aroma quality of different heat-treated milk， including pasteurized milk， ultra-high temperature instantaneous sterilized （UHT） milk and infusion technology sterilized （INF） milk.Methods The volatile flavor components of three kinds of heat-treated milk were identified by solid-phase microextraction gas chromatography mass spectrometry （SPME-GC-MS）， and the flavor of different heat-treated milk were also distinguished by electronic nose and electronic tongue.Results A total of 53 volatile compounds were identified， mainly including 13 aldehydes， 10 fatty acids， 9 alcohols， 7 ketones and 3 lactones. The major volatile compounds of pasteurized milk were octanoic acid， decanoic acid， nonanal and decanal； that of INF milk were octanoic acid， decanoic acid， acetic acid， octanal， nonanal， furfurol and 2-ethyl-1-hexanol； that of UHT milk were 2-heptanone， 2-nonanone， 2-undecanone， octanoic acid， hexanoic acid， propanal， nonanal， followed by δ-decalactone and δ-dodecalactone. The responses of the electronic nose to different milk differed significantly. The first two principal components in principal component analysis （PCA） could well distinguish the volatile flavor compounds of different milk. The sensors W5S， W1S， W1W and W2S played major roles in the flavor of milk. The e-tongue results showed that there were significant differences in umami and richness， and the first two principal components of PCA could completely distinguish different milk.Conclusion SPME-GC-MS combined with electronic nose and electronic tongue can be used to distinguish the aroma quality of different heat-treated milk.

Abstract:Objective A high performance liquid chromatography-tandem mass spectrometry method for the simultaneous determination of 42 kinds of antibiotics including quinolones， sulfonamides， nitroimidazoles and tetracyclines was developed for bean sprouts， dried bean curd and hot pot seasoning.Methods The samples were extracted with 70% acetonitrile-water （containing 0.1% formic acid）， purified by PRiME HLB， and separated by an Agilent Eclipse Plus C₁₈ column （150 mm×3.0 mm， 1.8 μm） with 0.2% formic acid acetonitrile and 0.2% formic acid water as gradient elution of mobile phase. The detection was performed under positive ion dynamic multiple reaction monitoring mode with electrospray ion source， and external standard method were used for quantification.Results The linear range of quinolones， sulfonamides and nitroimidazoles in bean sprouts， dried tofu and hot pot seasoning was 2-80 ng/mL， and the limit of detection was 5 μg/kg； the linear range of tetracyclines was 10-400 ng/mL， and the limit of detection was 25 μg/kg； the correlation coefficients were all greater than 0.997. The average recoveries of 42 kinds of antibiotics in three spiked levels were 85.4%-119.3%， and the relative standard deviations （n=6） was 0.4%-13.4%.Conclusion The method has a wide range of applications with easy operation and high sensitivity， and can rapidly screen the concentration of quinolones， sulfonamides， nitroimidazoles and tetracyclines in bean sprouts， dried tofu and hot pot seasoning.

Abstract:Objective An accurate and rapid method for simultaneous determination of fatty acids and squalene in vegetable oils by gas chromatography was established.Methods The samples were extracted with n-heptane and analyzed by gas chromatograph after saponification and esterification. The fatty acids were quantified by area normalization method， and squalene by external standard method.Results Thirty-seven fatty acids and squalene were well separated， and the qualitative and quantitative results were accurate. Squalene had a good linear relationship in the range of 2-500 mg/L with the correlation coefficient of 0.9997. Under three addition levels， the recoveries of squalene in the sample were 94.1%-104.6%. The relative standard deviations of squalene samples were 1.03% and 1.24%. The quantitative limits of squalene and fatty acid were 4 mg/kg and 0.0013 g/100 g respectively. The certified reference of peanut oil fatty acid was selected for verification test， the result met the requirements of the certificate， and was consistent with the national standard pretreatment method with the relative error less than 2%.Conclusion The method is accurate and reliable with high throughput， simple pretreatment operation and low energy consumption， which can greatly improve the detection efficiency and reduce the detection cost.

Abstract:Objective A method of UPLC-MS/MS for the determination of four ethylenebis dithiocarbamates in vegetables and fruits was established.Methods Samples were extracted with lcysteine hydrochloride and alkaline EDTA-Na₂ solutions， derived by methyliodide， prurified by QuEChERS method， and determined by UPLC-MS/MS.Results The limit of detection was 5 μg/kg for fruits and 10 μg/kg for vegetables. A good linear relationship was obtained between the peak area and concentration with the correlation coefficient over 0.998. The recoveries were from 82.3% to 115.1%， and the relative standard deviations were 2.3%-6.9%.Conclusion Ethylenebis dithiocarbamates in many kinds of vegetables and fruits could be successfully determined by the proposed method.

Abstract:Objective To develop a spectrophotometric method for the determination of sulfate in salt.Methods After excessive of barium chromate suspension was added to the sample solution， the filtrate contained chromate ions replaced by sulfate and appeared yellow， which could be quantified colorimetrically.Results The method had high precision with the RSD of 0.37%-2.34% （n=7）. And the recoveries was between 98.9% and 101.8% with good accuracy.Conclusion The method is suitable for the batch determination of sulfate content in salt with high precision， good accuracy and easy operation.

Abstract:Hazard Analysis and Critical Control Point （HACCP） is a management system generally recognized by countries around the world that can prevent and reduce food safety risks. In order to help small and micro food enterprises establish a scientific and efficient food safety management system， based on the high recognition of HACCP at home and abroad， the necessity of implementing the HACCP management system and the guidance documents for the implementation of HACCP management system for small and micro food enterprises were discussed. To provide some references for the majority of small and micro food enterprises， establish and maintain the effectiveness of the HACCP food safety management system， the documents from the International Codex Committee， the European Union， the United Kingdom and China are reviewed， and the differences between the establishment of HACCP system by small and micro enterprises and those of large and medium-sized enterprises are summarized.

Abstract:Food classification system is the basis of food safety supervision. Through sorting out and analyzing the main food classification systems at home and abroad， this paper points out the main problems existing in the current food classification system in China， and puts forward some suggestions to provide reference for improving the food classification system in China.

Abstract:The number of microbial indicators in Chinese food standards is small， the limit requirements are relatively loose， and there is no limit requirements for microorganisms in the processing process. The microbiological limit standards of meat and meat products in China， the European Union， the United States， Australia and Japan were collected and compared. Due to the different regions， cultures and economic development levels of various countries， there are obvious differences in the microbial limit requirements for meat and meat products. It is recommended to consider the actual production and dietary needs of meat and meat products in China， and learn from international standards to improve the microbial limit standard in China.

Abstract:Because of the large production and consumption of meat products in China， the food safety of meat products is related to the development of national economy and people’s health. The industrial chain of meat production includes breeding， slaughtering， processing， transportation and sales. The safety risks may exist in all parts of the industrial chain. It brings the safety risks diversity and complexity. The chemical， biological and physical risks of meat products and the causes of these risks are analyzed based on sampling data and processing technologies. The weaknesses of the supervision are summarized. The discussion on the technological innovation in supervision is proposed taking into account the risks and weaknesses in meat products. The technological innovation aims to optimize regulatory resources， expand regulatory scope， improve regulatory efficiency， ensure food safety and promote the development of meat industry.

Abstract:Heavy metals are important risk factors affecting infants and young children’s food safety， which is also the focus of food safety concerns of various countries and organizations. Formulation of strict limit standards is the important measure to control such risks. This article analyzes the status of heavy metal limit standards for infants and young children’s foods of Codex Alimentarius Commission， the European Union， the United States， Singapore， Australia and New Zealand， Canada， Republic of Korea and China. The differences are compared， suggestions are proposed to improve the standards in China， and issues that need to pay attention to in the production and supervision of imported and exported infants and young children’s foods are mentioned.

Abstract:Accurate and rapid detection of bisphenol A （BPA） in food plays an important role of reducing the hazard. Surface-enhanced Raman spectroscopy （SERS） technology， a new type of rapid detection technology， is being widely used in the detection of BPA in food. This article mainly reviews the mechanism of SERS， the application of SERS technology in the detection of BPA， and the latest research of rapid detection of BPA with different SERS substrates. The review can provide theoretical support for the detection of BPA in food and technological support for the safety supervision on food.

Abstract:Norovirus （NoV）， which transmits through food and water， can cause acute gastroenteritis worldwide. However， there is no specific antiviral drug. To prevent the spread of NoV outbreaks and intervene in time， only rapid detection and screening can identify NoV at the early stage. Traditional detection methods are time-consuming， labor-intensive， and the operation is cumbersome， which is not suitable for the real-time detection of NoV. Therefore， the establishment of NoV rapid detection technology has become an ongoing issue for researchers. Though many rapid detection methods have been reported， it is difficult to compare these methods because of the unculturable nature of NoV in vitro. Therefore， the currently reported rapid detection technologies are sorted out， and the research status at home and abroad is briefly introduced. The application and development trend of molecular biology， immunology， biosensor and other technologies in the rapid detection of NoV is reviewed. The detection limit， detection time， advantages and disadvantages of the methods are compared. It is expected to provide a reference for the on-site rapid detection of NoV and subsequent research of relevant novel detection technologies.

Abstract:To undestand the development of fluorine detection technology， the detection and analysis technology of fluorine in different food matrices in recent years are summarized， including fluoride ion selective electrode method， colorimetric method， ion chromatography， high performance liquid chromatography. Each various fluorine determination methods have their own advantages and disadvantages. And there are differences in the scope of application. It is the main research direction in the future to establish a detection technology for the determination of fluorine by ion chromatography with high sensitivity and selectivity.

Abstract:The identification methods and research progress of molecular serotyping of Salmonella are reviewed. The related genes encoding three antigens （O， H and Vi） of Salmonella are introduced. The methods and research progress of molecular serotype identification of Salmonella with serotype specific marker genes as targets are described. This paper reviews the identification methods and research progress of Salmonella serotype， which lays a foundation for further identification of molecular serotype of Salmonella.

Abstract:Association of Official Analytical Chemists standard for the determination of folate is more flexible， such as the use of strains， culture temperature， the use of more advanced equipment. There are still some gaps in these aspects in domestic standards. The relevant standards and regulations of the determination of folate in China， Codex Alimentarius Commission， European Union and the United States are compared from the aspects of the scope of application， strain， sample pretreatment， culture， determination method and others. In the process of drafting and revising the standards， the international standard system should be referenced and integrated gradually， standard review and training should be implemented to meet the needs of the lab.