Objective To investigate the prevalence, virulence phenotypes, and drug resistance phenotype of Vibrio parahaemolyticus in freshwater food, seafood, and ready-to-eat food in Yangzhou. Methods Freshwater food, seafood and ready-to-eat food samples were collected from 9 sampling points in Yangzhou markets for isolation and identification of Vibrio parahaemolyticus. The motility, hemolytic activity, and drug resistance phenotype of the isolates were analyzed. Results In 2023, a total of 289 samples were collected in the Yangzhou market, from which 63 strains of Vibrio parahaemolyticus were isolated, with an isolation rate of 21.80%. Among them, the isolation rate of freshwater food was 45.35% (39/86), seafood 28.75% (23/80), and ready-to-eat samples 0.81% (1/123), indicating a higher isolation rate in freshwater food compared to seafood in the markets of Yangzhou. The proportion of highly motility strains in freshwater food isolates was 30.77%, higher than that of the seafood isolates (17.39%). However, the proportion of strains with high hemolytic activity was 53.85% in freshwater food isolates, slightly lower than the 60.87% in seafood isolates. Antibiotic resistance profiling showed that all Vibrio parahaemolyticus isolates were resistant to ampicillin and cefazolin, while they were resistant to ceftazidime, tetracycline, ciprofloxacin, chloramphenicol, amikacin, meropenem and gentamicin. Conclusion This study highlights a high detection rate of Vibrio parahaemolyticus in Yangzhou markets and reveals differences in virulence and antibiotic resistance among isolates from different sources, offering valuable insights for monitoring and controlling the pathogen.

Objective To compare the taste characteristics, physical and chemical indicators of preserved mustards samples in market, and statistically analyze the correlation between taste quality and physical and chemical indicators. Methods The 22 samples of preserved mustards from Zhejiang, Sichuan and Hunan were collected, and the taste characteristics of preserved mustards were analyzed by artificial sensory evaluation and electronic tongue, the physical and chemical indicators such as moisture content, total acid, amino acid nitrogen, trichloroacetic acid (TCA) soluble peptides, nitrite, and reducing sugar content were analyzed. Results The saltiness and umami of preserved mustards were prominent, and the acidity intensity of different preserved mustards varied greatly. Umami was significantly negatively correlated with sourness and saltiness (P<0.01), and significantly negatively correlated with bitter aftertaste (P<0.05). Water content had a great influence on the taste quality of preserved mustards, and was significantly positively correlated with the taste (P<0.05). The salt content was significantly negatively correlated with the total acid content (P<0.01). Conclusion The taste characteristics and physical and chemical indexes of different preserved mustards samples are very different, and some preserved mustards have high salt content, so it is necessary to establish quality standards; the taste quality and physical and chemical indexes of preserved mustards from different origins does not show obvious regional characteristics; there is a negative correlation between the indexes of carbohydrate fermentation products and protein fermentation products in preserved mustards.

Mercury is a global environmental pollutant that poses potential threats to ecosystems and human health. Among the various chemical forms of mercury, methylmercury is of particularly concern due to its neurotoxicity and carcinogenicity. The consumption of aquatic products is a significant source of human exposure to mercury. To ensure food safety, stringent regulations have been established by different countries and regions, specifying the maximum allowable levels of mercury species such as total mercury and methylmercury in aquatic products, as well as the corresponding detection methods. This paper provided a comprehensive summary of the current international regulations on the maximum allowable levels of total mercury and methylmercury in aquatic products, and compared the standard detection methods for methylmercury in different countries. Through comparative analysis, investigated the characteristics of various extraction methods, including acidic, organic reagent, and distillation methods in depth. Additionally, this paper evaluated the advantages and disadvantages of common separation techniques, such as liquid and gas chromatography, summarized the performance of various detection methods, including liquid chromatography-atomic fluorescence spectrometry (LC-AFS), liquid chromatography-inductively coupled plasma mass spectrometry (LC-ICP-MS). These analyses not only revealed the limitations of existing detection methods but also provided a scientific basis and reference for the development and standardization of future methylmercury analytical techniques. This article further outlined the future direction of methylmercury determination in seafood, with the goal of enhancing the precision, accuracy, and sensitivity of detection methods to better support food safety.

Objective To establish a method for rapid determination of chromium content in aluminum food packaging based on fiber laser induced breakdown spectroscopy. Methods The sensitivity and limit of detection of laser induced breakdown spectroscopy and flame atomic absorption spectrometry optimized by laser pulse width, energy and baseline were evaluated with reference materials, and the 2 kinds of techniques were applied to the detection of aluminum food packaging samples, and the corresponding results were compared. Results For fiber laser induced breakdown spectroscopy, the time consumption was 2 min, the limit of detection was 5.2 μg/g, and the detected Cr content of coca cola packaging, aluminum foil paper and aluminum box were 45, 22, 21 μg/g, respectively. For flame atomic absorption spectrometry, the time consumption was 4 h, limit of detection was 7.2 μg/g, and the detected Cr content of these 3 samples were 136, 16, 14 μg/g, respectively. Conclusion This method is superior to the conventional flame atomic absorption spectrometry method in terms of analyzing speed, limit of detection and cost, and its detection results of commercial samples are similar to those of flame atomic absorption spectrometry, which proves the reliability of this method and its potential applicability in analysis tasks of limited time and large sample quantity.

Objective To establish a method for the determination of 25 kinds of illegal additives in candy by dispersive solid phase microextraction extraction coupled with ultra performance liquid chromatography-tandem mass spectrometry. Methods The samples were extracted with 50% methanol water, purified by dispersive solid phase microextraction extraction and separated by ACQUITY UPLC TSS T3 column. The samples were then eluted with ammonium formate aqueous solution and ammonium acetonitrile as mobile phase by gradient elution. The samples were determined by ultra performance liquid chromatography-tandem mass spectrometry and quantified by external standard method. Results The results showed that the 25 kinds of illegal additives had good linearity in the range of 2.00 to 50.00 µg/L with a correlation coefficient (r²) greater than 0.99, recoveries were between 65.1% and 99.3%, relative standard deviations were 1.1% to 5.0%, and limit of detection was 0.05 mg/kg and limit of quantification was 0.10 mg/kg. The method was applied to the detection of 105 batches of samples, in which one batch of compressed candy was found to contain xinlisita, and two batches of candy were found to contain dipropylphenidate. Conclusion The method is purified by dispersive solid phase microextraction extraction and detected by ultra performance liquid chromatography-tandem mass spectrometry. The method has good accuracy and high sensitivity, and can meet the detection requirements of 25 kinds of illegal additives in candy.

Objective To establish a detection method for simultaneously detecting 9 kinds of biogenic amines in aquatic products using the dansyl chloride precolumn derivazation-reverse phase high performance liquid chromatography. Methods The samples were extracted with a 5% trichloroacetic acid solution and derivatized with a 10 mg/mL dansyl chloride acetone solution. The derivatization reaction was terminated with ammonia, and the resulting solution containing the dansyl chloride derivatives of the 9 kinds of biogenic amines was made up to volume with acetonitrile. The sample solution was analyzed by reverse phase liquid chromatography using a C₁₈ column, with a mobile phase gradient of acetonitrile and water, and detected at 254 nm using a ultraviolet detector. Results The limits of quantitation of the 9 kinds of biogenic amines in aquatic products ranged from 1.08 to 7.59 mg/kg, with recovery rates ranging from 85.2% to 106.7% and precision ranging from 1.5% to 4.9%. The established method was used to analyze 50 batches of high-histamine fish sold in Guangzhou. The results revealed that the overall quality of the high-histamine fish in Guangzhou was good. β-phenylethylamine and cadaverine had relatively higher detection rates compared to other biogenic amines, but their content was all below 35 mg/kg. Histamine, putrescine, spermidine, agmatine, and arginine were not detected. Conclusion The method is fast, simple, and highly sensitive, making it suitable for batch sample determination of the 9 kinds of biogenic amines in aquatic products.

Objective To establish a method for simultaneous determination the content of 4 kinds of human milk oligosaccharides [2'--fucosyllactose (2'-FL), 3'-sialic acid (3'-SL), 6'-sialic acid (6'-SL) and lactose-N-neotetraose (LNnT)] in milk powder by liquid chromatography-fluorescence method. Methods The samples were dissolved in water, enzymolized with amyloglucosidase or β-galactosidase, derived with 2-aminobenzamide (2-AB) and 2-methylpyridine borane (2-PB), and separated by amide bonding column, detected by fluorescence detector, and quantitated by internal standard methods. Results The 4 kinds of milk oligosaccharides had a good linear relationship in the concentration range of 10-600 μg/mL, and the correlation coefficients (r²) were more than 0.999. The limits of detection and quantification of 4 kinds of milk oligosaccharides were 0.94-2.31 mg/100 g and 3.12-7.69 mg/100 g, respectively; the recovery rates of 4 kinds of milk oligosaccharides were 97.7%-101.5%, and the relative standard deviations (RSD) (n=7) were 0.53%-3.09%. Conclusion This method does not have high requirements for people, equipments and environment for determining the content of 4 kinds of milk oligosaccharides in milk powder. The pre-treatment operation is simple, and it has good accuracy and precision. It can provide a reference for the quality control method of human milk oligosaccharides in milk powder.

Objective To establish a method for the determination of biotin in formula food for special medical purposes by high performance liquid chromatography-post column derivatization. Methods The biotin in the sample was dissolved in water and extracted by enzymatic hydrolysis with amylase and papain at 60 ℃ for 1 hour in a water bath. Using Zorbax SB-AQ chromatographic column separation and entering the post column reaction device, the biotin was derived from fluorescein isothiocyanate labeled avidin. Derivatives were detected using a fluorescence detector with an excitation wavelength of 495 nm and an emission wavelength of 525 nm. The results were quantified by the external standard method. Results Under the optimized conditions, the biotin showed good (r²>0.999) linear relationships within the concentration range of 5.00‒75.00 ng/mL. The average recoveries were 97.5%‒100.1%, and the relative standard deviations were 0.86%‒2.9%. The limit of detection was 12 μg/kg, and the limit of quantification was 41 μg/kg. The relative standard deviations of the biotin standard solution and the sample solution to be tested within 24 h were 0.68% and 1.08%, respectively. There was no significant difference between the results of this method and GB 5009.256—2016 National food safety standard-Determination of biotin in food. Conclusion This method has simple pretreatment, high recovery, good sensitivity and precision, and can be used for the determination of biotin content in formula food for special medical purposes.

Objective To establish a quantitative analysis method for determining the content of 5 kinds of lactose derivatives (3'-galactosyllactose, 4'-galactosyllactose, 6'-galactosyllactose, 3'-sialyllactose, 6'-sialyllactose) in milk and dairy products by pre-column derivatization-high performance liquid chromatography. Methods The proteins in milk and dairy products were precipitated. The 5 kinds of lactose derivatives were reacted with 2-aminobenzamide at 55 ℃ for 120 min to label the fluorescent groups. The 5 kinds of lactose derivatives were separated by high performance liquid chromatography with an amide column and quantified by external standard method. Results The 5 kinds of lactose derivatives exhibited good linear relationships within the concentration range of 0.025-5.000 mg/L, with correlation coefficients (r) all exceeding 0.999. The limits of detection and quantification for the 5 kinds of lactose derivatives ranged from 3.5 to 7.5 mg/kg and 12.0 to 25.0 mg/kg, respectively. The recovery rates for the 5 kinds of lactose derivatives were between 90.8% and 103.3%, with relative deviations in detection results ranging from 2.8% to 5.3% (n=3). Conclusion This method demonstrates good precision, recovery rate, and sensitivity, making it suitable for determining the content of 5 kinds of lactose derivatives in milk and dairy products.

Curdlan, a type of microbial extracellular polysaccharide, is widely utilized as a food additive due to its exceptional gelling, water-holding, thickening, and freeze-thaw stability properties within food systems. In recent years, the research on the regulation of the interaction between curdlan and biomacromolecules has become a research hotspot in the field of food science, aiming at optimizing the texture of food, enhancing the stability of food, and promoting the development of new healthy foods. However, a systematic summary of the interaction between curdlan and biological macromolecules, as well as their regulatory mechanisms is still insufficient at present. As a result, this review offered a comprehensive overview of recent research progress in the interaction between curdlan and biomacromolecules, particularly emphasized the interactions between curdlan and polysaccharides, proteins and other macromolecules in food applications. This review aims to establish a theoretical foundation for the precise design and innovative development of functional foods.