Objective To investigate the inhibitory effects of tuna skin collagen oligo-peptide (TSCP) on melanin production and oxidative damage protection in Hacat cells. Methods Through investigated the effects of TSCP on melanin and tyrosinase production in B16-f10 cells, analyzed the antioxidant activity in B16-f10 cells, and assessed its protective effect against hydrogen peroxide (H₂O₂) induced oxidative damage in Hacat cells, the inhibitory mechanism of TSCP on melanin production and its protective mechanism against oxidative damage in Hacat cells were revealed. Results The experimental results showed that TSCP exhibits no significant cytotoxicity to B16-f10 cells at concentrations ranging from 0.01 to 1.00 mg/mL, and significantly inhibited tyrosinase activity and melanin production. At a concentration of 1.00 mg/mL, TSCP significantly reduced melanin content to 83.79%±4.31% (P<0.01) and tyrosinase activity to 78.14%±6.95% (P<0.001). TSCP also significantly reduced the levels of reactive oxygen species (ROS) in B16-f10 cells. At 1.00 mg/mL, the ROS levels decreased to 53.5%±4.4% of the control group (P<0.001), indicating potent antioxidant potential. Additionally, TSCP increased the activity of superoxide dismutase (SOD) to (16.62±0.62) U/mg prot (P<0.001) and reduced malondialdehyde (MDA) content to (0.352±0.051) U/mg prot (P<0.001). Glutathione peroxidase (GSH-Px) levels were also elevated, reaching (284.55±4.99) ng/mL at 1.0 mg/mL (P<0.01). In the Hacat cell model, TSCP similarly exhibited no significant toxicity and, in the H₂O₂-induced oxidative damage model, significantly improved cell viability and suppressed apoptosis. At 1.00 mg/mL, TSCP improved cell survival to 73.66%±5.48% (P<0.01), compared to the model group. Conclusion TSCP can inhibit melanin production, reduce oxidative stress, providing a foundation for its potential applications in skin whitening and antioxidant therapies.

Objective To compare the changes in muscle nutritional components and quality indicators of Trionyx sinensis at different stages of ecological purification breeding. Methods Nutritional parameters such as morphological index and protein, fat, amino acid and fatty acid in muscle and skirt were measured during the 0th, 15th and 30th d of purification, and the nutritional and quality changes of Trionyx sinensis were compared with the textural and structural characteristics. Results With the extension of ecological purification breeding time, the crude fat of Trionyx sinensis showed a trend of rapid decline followed by a slight increase, while the crude protein showed a trend of initial increase followed by a decrease. The total amino acid content showed a decreasing trend. In the entire ecological purification breeding process, there were significant changesin the crude protein and crude fat content in the muscles of Trionyx sinensis (P<0.05), as well as in the moisture and ash content of their skirts. There were significant differences in the content of saturated fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids before and after purification (P<0.05), and the content of saturated fatty acids and polyunsaturated fatty acids increased at 15 days. Except for valine and proline, all other amino acids decreased, and there was a significant decrease in cysteine, lysine, glutamate, histidine, aspartic acid, glycine, and alanine in the purified muscles after 30 days compared to the untreated ones (P<0.05). In the whole texture mode, the hardness, adhesion and mastication of the muscle of Trionyx sinensis purified for 15 days were significantly improved (P<0.05) compared with that of the muscle before purification. Conclusion Compared with traditional pond aquaculture of Trionyx sinensis, the crude protein content, essential amino acids, and total umami amino acids are significantly increased, and the optimal purification time is 15 d. Ecological purification breeding can improve the quality of Trionyx sinensis and better meet the needs of consumers. It is a purification breeding method worth applying in production practice, which is conducive to increasing the supply of high-quality and cost-effective Trionyx sinensis and providing research data for improving the quality of high-quality aquatic products.

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.

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 Establish a method for simultaneous determination of 11 kinds of caine anesthetics and their 3 kinds of metabolites in aquatic products by QuEChERS-liquid chromatography-tandem mass spectrometry. Methods The samples were extracted by acetonitrile, dehydrated by anhydrous MgSO₄ and NaCl, purified by 100 mg primary secondary amine (PSA), filtered by 0.22 µm organic microporous membrane, and qualitatively and quantitatively determined by liquid chromatography-tandem mass spectrometry. Results The 11 kinds of caine anesthetes and their 3 kinds of metabolites showed a good linear relationship in the mass concentration range of 0.01-5.00 μg/L, and the correlation coefficients (r) were 0.99529-0.99989. The limit of detection (LOD) and the limit of quantification (LOQ) of 11 kinds of caine anesthetics and their 3 kinds of metabolites were 0.05-2.00 µg/kg and 0.15-5.00 µg/kg, respectively. The 3 kinds of substrates, white shrimp, carp and turbinus were performed at 3 levels: 1 times LOQ, 2-2.5 times LOQ and 10 times LOQ. The recoveries of 11 kinds of caine anesthetics and their 3 kinds of metabolites in 3 samples were 71.3%-114.2%, 71.2%-107.0% and 70.4%-104.5%, and the relative standard deviations were 0.7%-11.2%, 0.5%-11.5% and 0.8%-14.2%. The method was used to detect 50 batches of different varieties of aquatic products in the market. The results showed that 4 batches of products were detected with caine anesthetic, and the other 46 batches were not detected, the detection rate was 8%. The detected items were mainly tricaine, benzocaine, m-aminobenzoic acid and p-aminobenzoic acid, the content of which were 5.68-90.80 μg/kg, and the other 10 kinds of compounds were not detected. Conclusions The method is simple and fast, has high sensitivity, accuracy and precision, and can simultaneously determine a variety of caine anesthetics in aquatic products. It is suitable for the determination of batch samples, and has high practical application significance, and can provide powerful technical support for food safety monitoring.

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.

Cronobacter spp. is a group of foodborne opportunistic pathogens widely present in the natural environment, characterized by their ability to tolerate desiccation and high osmolarity, enabling them to survive for extended periods in dried milk powder. Infant formula products may become contaminated during production, transportation, storage, and even during the reconstitution process. Infection with Cronobacter spp. can lead to severe illnesses such as bacteremia, meningitis, necrotizing enterocolitis in infants, and may result in serious neurological sequelae or even death. Therefore, establishing efficient and accurate detection methods for Cronobacter spp. is crucial for preventing and controlling these diseases, and holds significant importance in ensuring the quality and safety of infant formula products. Currently, the main detection methods for Cronobacter spp. include traditional culture-based methods, molecular biology methods, and immunological methods, with numerous studies in recent years reporting various degrees of improvement and optimization based on these methods. This article systematically reviewed the principles, advantages, and disadvantages of the various detection methods currently available for Cronobacter spp., aiming to provide a reference for further research in this field and for the optimization and updating of national standards and industry standards.

Objective To establish subsequently the real-time quantitative polymerase chain reaction (PCR) method that could quickly and accurately identify Cronobacter sakazakii, and design specific primer probes based on the DNA gyrB subunit gene. Methods The target gene sequences were searched and downloaded from National Center for Biotechnology Information (NCBI), sequence comparison was performed using DNAMAN, and primer probes were designed by Primer Express software. This established real-time quantitative PCR method was validated through specificity tests, absolute sensitivity tests, relative sensitivity tests and anti-interference tests. The 40 common pathogenic bacteria standard strains were selected for specificity validation. Results The results of multi-dimensional specificity validation showed that the method was able to specifically detect Cronobacter sakazakii, and there was no non-specific amplification for other closely related Cronobacter and common pathogenic bacteria in food. DNA detection sensitivity was 0.0100 ng/μL, while relative sensitivity was 10³ CFU/mL. The anti-interference experiment results showed that mixing interfering bacteria and their DNA with Cronobacter sakazakii DNA and Cronobacter sakazakii did not significantly affect the detection results, indicating that this method had good anti-interference ability. Conclusion The primer probes designed in this study are specific, rapid, sensitive and anti-interference for the detection of Cronobacter sakazakii in food samples under real-time fluorescence PCR method. It can provide technical support for detection of Cronobacter sakazakii in the future.

Objective To evaluate the antimicrobial resistance of bacteria in food animal in Quzhou City, Zhejiang Province from 2022 to 2023. Methods In the past two years, 690 swab samples from 40 livestock and poultry farms were randomly collected, and Escherichia coli and Enterococci were separated using selective culture medium. They were then identified by polymerase chain reaction and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. The minimum inhibitory concentration (MIC) of different antibiotics against these two bacteria was determined using broth microdilution method. Results In 2022, the highest antimicrobial resistance rate of Escherichia coli isolated from swab samples to tetracycline was 87.2%, with sulfamethoxazole following at 81.1%. One strain was resistant to meropenem and 5 strains were resistant to colistin. In 2023, the antimicrobial resistance rates of Escherichia coli isolated from swab samples to spectinomycin, florfenicol, trimethoprim/sulfamethoxazole, ceftiofur, and ofloxacin were all lower than those in 2022, and the antimicrobial resistance rates to meropenem and colistin were both 0%. The resistance rates of Enterococci isolated from swab samples to erythromycin, clindamycin, ofloxacin, cefotaxime, sulfamethoxazole, and tiamulin were all lower in 2023 than in 2022, while the resistance rates to penicillin, tetracycline, and linezolid were higher. No vancomycin-resistant enterococci were detected in either year. From the analysis of the antimicrobial resistance rates, MIC distribution, and antimicrobial susceptibility profiles of Escherichia coli and Enterococci over the two years, it could be concluded that both bacteria demonstrated decreased resistance to most antibiotics, with Escherichia coli showing a more significant reduction. Conclusion In 2023, the overall resistance level of Escherichia coli and enterococci of food-animal origin in the Quzhou Area has declined significantly compared to 2022. However, multi-drug resistance still exists and the spectrum of resistance is rather broad, posing a threat to food safety and human health.

Objective To study the growth heterogeneity of different serotypes of Vibrio parahaemolyticus (VP) under different culture conditions, and to establish growth prediction models for epidemic strains (O3:K6, O10:K4). Methods Seventeen VP strains of different serotypes were selected as the research objects, and different culture conditions were set, including salinity (0.5%-10.0%), pH (3.0-11.0) and temperature (16-50 ℃). The modified Gompertz model was used to establish the primary growth model. The optimal growth range was determined by comparing the maximum OD value (Y_max), the Lag time (λ) and maximum specific growth rate (μ_max). The second-order response surface growth model was established by Design-Expert 13 software. Results There was growth heterogeneity among VP strains. The coefficient of variation for differences in growth parameters μ_max and Y_max between VP strains at salinity levels of 1.0%-3.0%, pH of 7.0-9.0, and temperatures of 20-40 ℃ was lower than that under other culture conditions. The growth ability of the epidemic strains (serotype O3:K6, O10:K4) was significantly greater than that of other serotypes when the salinity was 7.0%, the pH was 10.0, and the temperature was 16 ℃, with a statistically significant difference (P<0.05). The determination coefficients of the first-order growth models fitted under different salinity and temperature were greater than 0.98, and the correlation coefficients under different pH were greater than 0.9. The second-order response surface growth model was significant (P<0.05), and the determination coefficient was greater than 0.94. Conclusion There is growth heterogeneity among VP strains, but in certain extreme conditions, there are more obvious growth differences between different serotypes. The modified Gompertz model and the second-order response surface growth model can be used to analyze and predict the growth of VP under different experimental conditions, which can provide reliable and safe prediction for the growth trend of VP.