Pathogenic bacteria has always been a hot topic of social concern, which is one of the important factors to harm food safety and public health. Rapid and accurate detection of pathogenic bacteria is of great significance to people’s health and social stability. In recent years, due to the drawbacks of traditional methods such as cumbersome process, low sensitivity and single detection type, researchers have developed various fluorescence sensors for rapid and accurate detection of pathogenic bacteria through reasonable modification of nanoclusters by various means. This paper focused on the physical and chemical properties of gold nanoclusters, summarized the latest research progress of gold nanoclusters for pathogenic bacteria detection from the perspective of direct and indirect reaction from the different modes of action of gold nanoclusters and target bacteria, and discussed and prospects the shortcomings and possible development directions of gold nanoclusters in the future. The aim is to provide reference for the rapid detection of pathogenic bacteria by gold nanoclusters.

Objective To establish a method for the determination of the migration of 9,9-bis(methoxymethyl)fluorene in plastic food contact materials and articles by gas chromatography-mass spectrometry. Methods The water-based food simulants were extracted by n-hexane, and the chemical alternative solvents (95% ethanol and isooctane) were directly injected, and the olive oil simulants were extracted with acetonitrile and then injected, and the samples were analyzed by gas chromatography-tandem mass spectrometry and quantified by external standard method. Results A method for the determination of 9,9-bis(methoxymethyl)fluorene in plastic food contact materials was established. The limit of detection was 0.01 mg/kg or mg/L, the limit of quantification was 0.03 mg/kg or mg/L, the recovery rates were 80.0%-110.0%, and the relative standard deviations were 1.2%-6.0% (n=6). The actual samples of 10 kinds of polypropylene (PP) food contact materials were determined by this method, and the detection rate was 10%, and the detection concentration was 0.12 mg/kg. Conclusion The method is sensitive, has high recovery and accuracy, and the limit of detection can meet the requirements of regulations, and can be used for the practical testing of the migration of 9,9-bis(methoxymethyl)fluorene in polypropylene (PP) food contact materials.

Objective To establish a method for the determination of fluoride ion in tea and tea beverages by activated carbon purification-ion chromatography, and then to study the health risks of tea water and tea beverages. Methods The experiment was carried out by brewing 6 kinds of tea in 2 ways respectively. Method 1: Tea was brewed in a time gradient. Method 2: Add tea once, brew tea with several times and then collect tea. Collect tea by brewing tea with water several times. The tea and tea beverages were purified by activated carbon, filtered by 0.45 μm microporous filter membrane, separated by AS23 ion chromatographic column (4.0 mm×250 mm) with 4.5 mmol/L Na₂CO₃ and 0.8 mmol/L NaHCO₃ solution as leach solution, and tested by ion chromatography. The health risk was assessed by the highest tea fluoride dissolution with method 1, the total tea fluoride dissolution with method 2 and tea fluoride content in tea beverages. Results Under the optimal analysis conditions, the limit of detection of fluoride ions was 0.016 mg/L. In the range of 0.1-5.0 mg/L, the linear relationship was good, the correlation coefficient (r²) was 0.9996, the recovery rates were 94.93%-105.32%, the relative standard deviations were 1.02%-2.13% (n=6). The method detected the amount of fluoride ion dissolved in tea, and found that the dissolution increased continuously with the extension of brewing time and reached the highest value. With the increase of brewing times, the dissolution of fluoride ion in tea increased first, and then the decline trend gradually slowed down. The dissolution rate of fluoride ion in the first 2 brewing times reached more than 65% of total dissolution. Conclusion The method has high sensitivity, good accuracy, simple operation and practical value. Daily intake of tea fluoride in tea and tea beverages obtained from 6 kinds of tea under 2 brewing methods are in line with the daily intake limit of fluoride recommended by China and the World Health Organization. The target hazard quotient (THQ) values are less than 1, and there is no significant health risk to human. It is recommended to reduce tea brewing time, wash tea, and choose high-quality tea to drink tea scientifically and healthily.

Objective To establish an automatic, fast and high-resolution detection method for 5 kinds of common pathogenic bacteria in aquatic products, and improve the efficiency and accuracy of detecting pathogenic microorganisms in aquatic products. Methods Genes of owpW, tlh, invA, femA, and prfA from Vibrio cholera, Vibrio parahaemolyticus, Salmonella, Staphylococcus aureus, and Listeria monocytogenes were amplified by multiple polymerase chain reaction (PCR). PCR products were used as templates for single nucleotide extention and molecular weight of the extended probes was detected on the mass spectrometer. The molecular weight of probes for genes owpW、tlh、invA、femA and prfA were 4848, 5435, 5890, 6560 and 7096 Da. The molecular weights of the extended probes were 5119 Da (plus A), 5697 Da (plus T), 6137 Da (plus C), 6822 Da (plus T) and 7383 Da (plus G), respectively. This finally determined system was verified by reproducibility test, specificity test, sensitivity test and detection test of artificially contaminated aquatic samples. Results Using a sample of mixed DNA from 5 kinds of different bacteria as a template for nucleic acid mass spectrometry detection, the corresponding 5 kinds of probes could be extended simultaneously with an extension efficiency greater than 80%. The above 5 kinds of bacteria would not be detected in samples using interfering bacteria as templates. The sensitivity for detecting Salmonella, Staphylococcus aureus, Listeria monocytogenes, Vibrio parahaemolyticus, and Vibrio cholerae could reach 150, 350, 160, 130, and 180 CFU/mL, respectively. Conclusion This method demonstrates good reproducibility, specificity, and sensitivity, and has a high degree of automation, which can meet the detection needs of the above 5 kinds of microorganisms in aquatic products simultaneously.

Iodine is essential for the synthesis of thyroid hormones in humans, it plays an important role in the prevention and treatment of diseases caused by endemic iodine deficiency disorders and hereditary thyroid dysfunction, eta.. Excessive or deficient iodine intake both have negative effects on human health. Seaweed, as a quality food source rich in iodine, is an ideal natural iodine supplement. With the increasing incidence of thyroid disease, it has led to a rejection of seaweed products with high iodine content, such as Laminaria japonica. A large number of studies show that there is no direct data to suggest that excessive consumption of seaweeds can have adverse effects our body despite the high iodine conten. Therefore, the paper summarized the research progress on morphological distribution of iodine from seaweed, safety evaluation of different forms of iodine, changes of speciation before and after processing, as well as bioavailability of iodine in edible seaweeds. This study provides ideas for evaluating the edible safety of iodine in seaweeds, and also provides scientific evidence for the healthy development of seaweed industry.

Objective To establish a method for the determination of 15 kinds of chemicals illegally added in prefabricated food by ultra performance liquid chromatography-triple quadrupole composite linear ion trap mass spectrometry in multiple reaction monitoring-information dependent acquisition-enhanced product ion (MRM-IDA-EPI) mode combined with pass-through solid phase extraction technology. Methods The samples were extracted with 1% (volume fraction) formic acid in acetonitrile. The extractive solution was purified by pass-through solid phase extraction column Captiva EMR-Lipid, and the purified liquid was separated on a Agilent Poroshell 120 EC-C₁₈ (2.1 mm×100 mm, 1.9 μm) column. The mobile phase was acetonitrile and 5 mmol/L aqueous ammonium acetate containing 0.05% formic acid. The target compounds were detected by MRM-IDA-EPI mode with external standard method. Results The calibration curves of the 15 kinds of compounds were linear in the concentration range within limits with correlation coefficients between 0.9956 and 0.9996. The limits of detection ranged from 0.62-62.50 μg/kg. The average recoveries of 15 kinds of compounds at 3 different levels ranged from 78.33%-109.51% with accuracy of 0.67%-14.02%. Conclusion The method can be applied to the determination of 15 kinds of chemicals illegally added in prefabricated food with its rapidity, high accuracy and high precision, providing support for quality control and market regulation of prefabricated food.

In recent years, Actinidia industry has developed rapidly in China. The Actinidia plant area and production both rank the first all over the world. The standardization of Actinidia production are becoming higher. But it lacks competitiveness in quality and trade, can not meet the domestic and international market demand for high-quality Actinidia. Therefore, perfecting the quality and safety standard system of Actinidia in our country will be an important method to improve the market competitiveness. This article systematically sorts out China’s current Actinidia quality and safety standards, summarizes the quality and safety of each link of Actinidia before, during and after production, analyzes the current situation of China’s Actinidia quality standard system construction, as well as the main problems, and puts forward suggestions for the construction of the whole process of Actinidia quality and safety control system, in order to promote the high quality development of China’s Actinidia industry.