Objective To establish a method for the determination of migration of isosorbide in isosorbide modified polyethylene terephthalate (PET) products by gas chromatography-flame ionization detector (GC-FID). Methods The effects of different chromatographic conditions on the separation of isosorbide were investigated. HP-5 was selected as the separation column and 260 ℃ was selected as the injection port temperature. The effects of different pretreatment methods on the extraction of isosorbide from food simulants were investigated. The olive oil food simulant was extracted with methanol, purified with n-hexane and filtered before analyzed. The 95% ethanol and isooctane simulants were directly analyzed by the machine after filtered. Other food simulants were diluted with methanol and then directly analyzed by the machine. The external standard method was used for quantification. Results Isosorbide had a good linear relationship in the range of 2.5-40.0 mg/L (aqueous food simulants), 0.6-10.0 mg/L (substitute simulants) and 1.5-25.0 mg/kg (fatty food simulants), and the correlation coefficient was above 0.995. The limit of detection of this method for the migration of isosorbide was 0.8 mg/kg (aqueous food simulants), 0.2 mg/kg (substitute simulants) and 0.5 mg/kg (fatty food simulants). The limit of quantification was 2.5 mg/kg (aqueous food simulants), 0.6 mg/kg (substitute simulants) and 1.5 mg/kg (fatty food simulants). The spiked recoveries were 92.0%-112.3%, and the relative standard deviation was 0.2%-4.3% (n=6). Conclusions This method has good linearity, high precision, sensitivity and accuracy, and can meet the detection requirements of isosorbide migration in modified PET products.

Objective To study the tissue distribution and metabolic regulation of diazepam (DZP) in Carassius auratus after feeding with positive bait containing DZP. Methods Carassius auratus was selected as the study object and exposed to DZP-enriched bait through gavage, and tissue samples including scales, skin, muscle, plasma, gills, intestines, liver, gallbladder, gonads, and brain were collected at specific intervals ranging from 1 h to 456 h post-exposure. High performance liquid chromatography coupled with tandem high-resolution mass spectrometry was employed to detect DZP and its metabolites—nordazepam (NZP), temazepam (TZP), and oxazepam (OZP)—in these tissues, analyze their distribution and metabolic patterns. Results Following exposure to DZP-enriched bait, DZP rapidly accumulated in Carassius auratus tissues, with substantial residues persisting for up to 456 h. The highest concentrations were primarily found in the gonads, liver and gallbladder, with the gonads consistently showing elevated levels. NZP and TZP emerged as the primary metabolites. Conclusion DZP predominantly exists in its prototype form in Carassius auratus and tends to accumulate in the gonads. The prolonged metabolic cycle of DZP and its metabolites in Carassius auratus indicates potential food safety and health risks for consumers of aquatic products caught with DZP-containing bait.

Objective To compare three domestic and foreign Cronobacter detection methods, for verifying the actual detection performance of three standard methods: GB 4789.40—2016 National standard for food safety food-Microbiology tests Cronobacter spp. (Enterobacter sakazakii) test, GB 4789.40—2024 National standard for food safety food-Microbiology tests Cronobacter test and ISO 22964—2017 Food chain microbiology-Horizontal detection methods for Cronobacter spp. Methods Three standard methods were used to detect Cronobacter in 403 samples collected from 2020 to 2022, including infant formula, cereal-based infant supplements, corn ingredients, and raw and supplemental ingredients of infant formula, and to test Cronobacter isolates for drug susceptibility. Results The total contamination rate of Cronobacter in 403 samples was 17.9% (72/403), and the contamination rates of corn raw material, cereal-based infant supplement and infant formula were 37.3% (38/102), 23.4% (33/141) and 1.0% (1/100), respectively. Although there was no significant difference in the total detection rate among the three standard methods (χ²=3.601, P=0.170), 41.5 ℃ could effectively improve the detection rate compared with 44 ℃ (χ²=18.813, P=0.000). The resistance rate of 72 strains of Cronobacter was 55.6% (40/72), among which the resistance rates of cefazolin, ampicillin, and amoxicillin/clavulanic acid were 52.8% (38/72), 5.6% (4/72), and 1.4% (1/72), respectively. Conclusion This study shows that GB 4789.40—2024 has reached the level of the international relevant methods, providing data support for the mutual recognition of the test results of GB 4789.40 and ISO 22964 methods. Cronobacter has high resistance to cefazolin, which should be avoided when choosing antibiotics for clinical treatment.

Objective To study the effects of methyl-β-cyclodextrin (M-β-CD) on removing cholesterol from fish oil. Methods Cholesterol removal rate and fish oil recovery rate were used as key indicators to screen suitable materials for removing cholesterol from fish oil from β-cyclodextrin (β-CD) and its derivatives. The optimal cholesterol removal process conditions were determined through orthogonal experiments, and the quality of fish oil before and after cholesterol removal was compared. Results M-β-CD was the best material for removing cholesterol from fish oil. The optimal process conditions of M-β-CD removal of cholesterol in fish oil were as follows: M-β-CD dosage of 30%, temperature of 50 ℃, time of 15 min. The cholesterol removal rate was 51.34%, and the fish oil recovery rate was 84.84% under these conditions. When cholesterol was removed under the optimal process conditions, the acid value, peroxide value, and anisidine value of fish oil significantly decreased (P<0.05), while the iodine value did not change significantly (P>0.05). The content of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) significantly increased (P<0.05), the proportions of saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), and polyunsaturated fatty acids (PUFA) were 31.33%, 16.81%, and 51.86% of the total lipid content, respectively, with no significant changes observed among them (P>0.05). Conclusion The treatment of fish oil with M-β-CD not only efficiently removes cholesterol but also enhances the quality, making it a promising method for cholesterol removal from fish oil.

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.

Objective To investigate the effects of shading and drought on the quality of black tea and white tea in summer and autumn. Methods Light fermented white tea and heavy fermented black tea were processed through multiple experimental settings of shade, drought, and a combination of shade and drought. The 4 groups of black tea and white tea samples were evaluated for sensory quality. Additionally, high performance liquid chromatography (HPLC) and headspace solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) technologies were employed to conduct a comparative analysis of quality components and taste components. Results Shading combined with drought treatment increased the levels of water extracts, free amino acids, umami amino acids such as theanine, sweet amino acids like threonine, alcohols, thereby significantly enhanced the fresh taste of the tea (P<0.05). Concurrently, in black tea, the concentrations of bitter amino acids such as valine, tea polyphenols, catechins were reduced, leading to a marked decrease in the bitterness and astringency of summer and autumn tea (P<0.05). Aroma testing revealed a total of 98 substances in black tea, with alcohols being the most prevalent. The concentration in the shade plus drought group was significantly higher than the drought group (P<0.05). In white tea, 85 substances were identified, with alcohols comprising the largest proportion. Conclusion The findings of this study offer new insights for the production of black and white tea under extreme summer and autumn weather conditions. This approach not only effectively mitigates the bitterness of summer and autumn tea but also enhances the utilization rate of fresh leaves, providing crucial guidance for tea garden production management.

Objective To delve into the influences of slightly acidic electrolyzed water (SAEW) and ultra-high pressure (UHP) on the bactericidal potency of Panax notoginseng tubers, and quantification of synergistic bactericidal effect, constructing bactericidal model. Methods Fresh Panax notoginseng was selected as the raw material, with independent variables encompassing SAEW available chlorine concentrations (25, 30, 35 mg/L), solid-liquid ratios (1:20, 1:30, 1:40 g/mL), treatment durations (4, 6, 8 min), and pressures (200, 300, 400 MPa). The number of deceased Escherichia coli on the surface of Panax notoginseng tubers was set as the response value. A response surface methodology was adopted to optimize these treatment parameters and establish a coordination range for parallel SAEW-UHP treatments while quantifying their synergistic effects, verified the prediction accuracy of the model. Results Revealed that based on single-factor experiments, SAEW-UHP parallel technology was better than single technology in bactericidal effect, the optimal sterilization process parameters for the SAEW-UHP parallel technology lie within a solid-liquid ratio range of 1:26.90-1:33.34 g/mL, available chlorine concentrations range of 29.03-35.00 mg/L, treatment durations range of 5.27-6.83 min, pressure range of 295.57-400.00 MPa and the material-to-liquid ratio was set at 1:31.28 g/mL, with an electrolyzed water concentration was set at 34.25 mg/L, treatment duration was set at 6.79 min, and the pressure was set at 400.00 MPa, the synergistic effect predicted by the model reached its maximum, yielding a peak quantification value of 1.87 lg(CFU/mL). Conclusion This research quantitatively elucidates the augmented sterilization efficacy conferred by the SAEW-UHP parallel technology, utilized the smallest dosage and the lowest processing intensity to achieve the best bactericidal effect, which furnishing a theoretical underpinning for fresh produce storage strategies, offering novel approaches to green processing, and providing a guarantee for food microbial safety.

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 explore the genes that respond to the synthesis pathway of norovirus binding receptors in Crassostrea gigas under different temperature stress, screen them, and study their cloning and expression patterns. Methods Crassostrea gigas were treated at high temperature (25 ℃) and low temperature (5 ℃), and two tissues of gills and digestive glands were extracted for RNA extracted for transcriptome sequencing and analysis. Selected genes on the synthesis pathway of norovirus binding receptors that responded to temperature treatment as targets, clone, express in prokaryotic cells, and identified by Western blotting. The tissue expression and seasonal expression pattern of the gene were analyzed by quantitative real time-polymerase chain reaction (qRT-PCR). Results The β1,3 galactosyltransferase-like 1 (B3GALT1-like) gene (GenBank LOC117683256) was significantly upregulated in multiple sampling sites in the gill group. The 1089 bp coding sequence (CDS) region of the gene was amplified. After 8 h of induction of 25 ℃, isopropyl beta-D-1-thiogalactopyranoside (IPTG), a protein band of about 84.9 kDa appeared, which was specifically bound to both anti-MBP tag antibody and anti-human B3GALT1 antibody. B3GALT1-like genes was abundantly expressed in gill tissue and was significantly higher at low temperature than at high temperature (P<0.01). Conclusion The expression level of B3GALT1 gene in Crassostrea gigas is affected by temperature, and the expressed protein has similar immunogenicity to human β1,3 galactosyltransferase. The tissue expression and seasonal expression patterns of the B3GALT1 gene are somewhat consistent with the seasonality of norovirus outbreaks. This study provides a foundation for further exploration of the molecular mechanism of seasonal enrichment of norovirus in Crassostrea gigas.

Objective To understand the exposure of tetrodotoxin in wild and farmed shellfish in coastal cities of Zhejiang Province in 2022. Methods Used stratified random sampling method, liquid chromatography tandem mass spectrometry was used to determine tetrodotoxin in the samples, combined with the Report on nutrition and chronic disease status of Chinese residents (2015) and the 2014 National physical fitness monitoring bulletin to investigated the dietary intake of residents. Using the point assessment method recommended by the World Health Organization/Food and Agriculture Organization of the United Nations for Assessment of dietary exposure to chemicals in food, the level of tetrodotoxin in the diet of residents in several coastal cities in Zhejiang Province was evaluated. Results The content of tetrodotoxin in shellfish varied greatly, mainly concentrated in rainbow cherry clams and striped snails, with a detection rate of 14.7% and a maximum of 5220.00 μg/kg. The average content of tetrodotoxin was 167.30 μg/kg. When children under 10 years old consumed less than 15 g, adolescents aged 10-20 years old consumed less than 40 g, and adults over 20 years old consumed less than 60 g at once, their acute dietary exposure level was in an acceptable and safe state; the acute risk index for ingesting other shellfish was much lower than 100, indicated that the population’s exposure level was in a safe state. Conclusion The overall acute dietary exposure level of shellfish was in a safe state, and the content of tetrodotoxin in striped snails is extremely high. Eating striped snails is extremely unsafe and shall be regulated.