Objective To investigate the microbial contamination in frozen drinks sold in Taicang City from 2022 to 2024. Methods A total of 118 samples of frozen drinks sold in Taicang City were collected from 2022 to 2024, inspected and judged according to GB 2759—2015 National food safety standard-Frozen drinks and ingredients. Results One sample had an excessive total bacterial count, and 4 samples had an excessive coliform group, with failure rates of 0.85% and 3.39%, respectively; the 72.88% (86/118) of the samples had a measured total bacterial count of greater than or equal 5 CFU/g, and 6.78% (8/118) of the samples had a measured coliform bacterial count of greater than or equal 5 CFU/g; Staphylococcus aureus, Salmonella and Listeria monocytogenes were not detected in the sample. Conclusion From 2022 to 2024, the hygiene quality of frozen drinks sold in Taicang City is relatively good. It is recommended that regulatory authorities continue to conduct hygiene supervision on frozen drinks production enterprises. Enterprises continue to strengthen hygiene management, control production, transportation and storage processes, to ensure the hygiene quality of frozen drinks.

N-nitrosamines (NAs) are a class of strongly carcinogenic compounds with high contamination levels in aquatic products, posing significant risks to human health. Recent random inspections in China have revealed that excessive N-nitrosodimethylamine (NDMA) content has become a major factor disqualifying processed aquatic products, seriously hindering the healthy development of the aquatic product processing industry. Therefore, elucidating the formation mechanisms and influencing factors of NAs in aquatic products, along with controlling their levels through processing technologies and multidisciplinary approaches, has become a key research focus. This review systematically examined various formation pathways of NAs in aquatic products, pretreatment methods, and analytical techniques compliant with national food safety standards. It further summarized comprehensive strategies for NAs control, including reduction of NAs precursor intake, blocking of NAs formation pathways, and decomposition of existing NAs. The paper aimed to address the excessive NAs levels in aquatic products, thereby ensuring the quality and safety of aquatic products and promoting sustainable development of the industry.

Objective To develop a sensitive and stable dual signal output indicator label and realize real-time monitoring of the freshness of Litopenaeus vannamei. Methods Based on polyvinyl alcohol (PVA)/agar composite matrix combining anthocyanins (ACNs), silver coated gold nanoparticles (Au@AgNPs) and the metal organic framework material UiO-66, the dual signal output indicator labels were prepared by casting method. Next, the stabilizing effect of UiO-66 on the labels was investigated by storage stability, ultraviolet stability and anti-migration experiments. Ammonia, dimethylamine and trimethylamine were used as characteristic volatile markers to evaluate the gas sensitive response performance of the labels. Ultimately, the label was applied to real-time monitoring of the freshness of Litopenaeus vannamei. Results Compared to labels without UiO-66, the addition of UiO-66 effectively immobilized the anthocyanins and improved the UV stability and storage stability of the label. In addition, the label showed excellent responsiveness to ammonia and amine gases. In the application of freshness monitoring of Litopenaeus vannamei, the color of the indicator label gradually changed from purplish-red to bluish-green with the change of freshness of Litopenaeus vannamei. The partial least squares regression (PLSR) model based on the surface-enhanced Raman scattering (SERS) signals showed excellent prediction performance for the total volatile basic nitrogen (TVB-N) values, with a correction set coefficient of calibrated coefficient of determination (R²_C) of 0.951, cross-validated coefficient of determination (R²_CV) of 0.899, predicted coefficient of determination (R²_P) of 0.966, and residual prediction deviation (RPD) of 4.765. Conclusion A colorimetric-SERS dual-signal output indicator label is developed in this study. The label enable simultaneous visual identification of the freshness of Litopenaeus vannamei and high-sensitivity prediction of TVB-N values, providing a reference for the design of novel intelligent food packaging systems.

Objective To establish a pre-amplified quantitative real-time polymerase chain reaction (qPCR) method for the detection of Oncorhynchus mykiss source components. Methods The study developed an enhanced pre-amplified qPCR method, which was based on the validation and improvement of the existing standard qPCR method and compared the performance of both methods. Results Specificity testing of the standard qPCR method revealed cross-reactivity with closely related species, such as Coho salmon and Atlantic salmon. The established improved pre-amplified qPCR method, which incorporated a pre-amplification step, exhibited high specificity and no cross amplification was observed for Coho salmon, Atlantic salmon and other closely related species. The amplification efficiencies of the standard qPCR and the pre-amplified qPCR methods were 90.25% and 104.91%, respectively. The lowest limits of detection of the 2 kinds of methods were 2.99×10^-3 ng/μL (0.83-8.87 pg/μL, 95% confidence interval) for the standard qPCR and 1.50×10^-4 ng/μL (0.09-0.27 pg/μL, 95% confidence interval) for the pre-amplified qPCR. Conclusion The method established in this study has the characteristics of strong specificity, high sensitivity, and is suitable for authenticity and adulteration detection of Oncorhynchus mykiss source components in food products.

Objective To establish an analytical method for the simultaneous determination of 6 kinds of fluoroquinolones and 4 kinds of benzodiazepines residues in aquatic products by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Methods Aquatic product samples were extracted with 1% formic acid in acetonitrile. The extracts were concentrated with a rotary evaporator and then reconstituted in 90% acetonitrile aqueous solution (containing 1% formic acid), and purified through a pass-through solid phase extraction cartridge (ProElut PLS-A). The purified extracts were directly analyzed by UPLC-MS/MS. Quantification was performed using the isotope internal standard method. Results The 10 kinds of target compounds exhibited good linearity within the concentration range of 0.5 to 50.0 ng/mL, with correlation coefficients (r) all greater than 0.998. The limits of quantitation for these compounds in 5 kinds of different aquatic product matrices ranged from 0.5 to 1.0 μg/kg. The recovery rates at low, medium and high spiking levels ranged from 81.5% to 109.7%, with relative standard deviations ranging from 0.24% to 13.22%. Conclusion Methodological validation confirmed that the developed method is highly sensitive, accurate in quantification, stable, and straightforward in operation. It is suitable for high-throughput detection of 6 kinds of fluoroquinolones and 4 kinds of benzodiazepines residues in aquatic products.

Objective To optimize the protein extraction process of Pectinidae. Methods A combination of composite enzymes and segmented enzymatic hydrolysis was employed, utilizing different protease enzymes with mode of enzyme digestion and cleavage sites. Significant factors were screened by single factor combined with Plackett-Burman and Box-Behnken model was used to optimize the one-stage protein extraction process, and the parameters of the two-stage enzymatic digestion process were optimized by orthogonal tests. Results The optimal extraction conditions for complex enzyme-assisted stepwise hydrolysis in protein extraction were as follows: The optimal extraction process parameters of the one-stage were as follows, solid-liquid ratio was 1:3.9 (m:V), enzyme digestion time was 80.0 min, compound enzyme addition was 1.1%, complex enzyme ratio (trypsin:alkaline protease) was 1:2 (m:m), enzyme digestion pH was 8.2, enzyme digestion temperature was 52.5 ℃; the optimal extraction parameters of the two-stage were as follows: Enzyme digestion pH was 7.0, enzyme digestion temperature was 50.0 ℃, neutral protease addition was 0.8%, and enzyme digestion time was 40 min. Under these conditions, the protein extraction rate was 76.3%. Conclusion Due to synergistic and complementary effects between the complex enzymes and segmented enzymatic hydrolysis, the protein extraction rate of Pectinidae is effectively improved, which provide some theoretical basis for the subsequent development and utilization of proteins from Pectinidae.

Objective To establish a rapid detection model for the nutritional components of Oncorhynchus mykiss based on near-infrared spectroscopy (NIR). Methods Firstly, near-infrared spectral data of 200 Oncorhynchus mykiss were collected. Then, the content of 3 kinds of nutritional components (moisture, fat and protein) of each Oncorhynchus mykiss were determined by national standard methods. The near-infrared spectral data and nutritional component data were matched one by one. The near-infrared rapid detection model was established by combining NIR with partial least squares (PLS), and the best detection model was screened out. Results The pretreatment method of the moisture content detection model was multiple scattering correction (MSC), and the optimal model was obtained when the wavelength range was 4000-10000 cm^-1. The pretreatment method of the fat content detection model was standard normal variable (SNV), and the optimal model was obtained when the wavelength range was 5000-7144 cm^-1 and 7404-10000 cm^-1. The pretreatment method of the protein detection model was second derivative (ds2)+SNV+Savitzky-Golay smoothing (sg9), and the optimal model was obtained when the wavelength range was 4100-5100 cm^-1 and 5400-9000 cm^-1. The Q value, the correlation coefficient of the correlation coefficients, and the correlation coefficient of prediction of the optimal model were all relatively large, and the standard deviation of square error corrected and standard error of cross validation were close to each other, which met the best modeling principle. Conclusion The best model is verified by the prediction set that do not participate in the modeling. The absolute deviation between the predicted value and the true value (determined by the national standard method) is no more than 5.7%. This indicates that the model can be used for the detection of three nutritional components of Oncorhynchus mykiss, and can achieve non-destructive and rapid detection of the nutritional components of Oncorhynchus mykiss, saving detection costs and shortening the detection cycle.

Objective To evaluate the pollution levels of five harmful heavy metals in different tissue parts and whole crabs of imported Cancer pagurus (common yellow crabs), clarify their distribution characteristics and food safety risks. Methods According to the national standard GB 5009.268—2016 National food safety standard-Determination of multielements in food, inductively coupled plasma mass spectrometry (ICP-MS) was used to detect the content of arsenic, cadmium, chromium, mercury, and lead in 9 parts of Cancer pagurus liver, pancreas, crab roe, crab gills, crab body meat, crab leg meat and whole crab. The differences in heavy metal enrichment and exceedance in different parts were analyzed. Results Cadmium pollution was the most prominent, with the highest content in the liver and pancreas (up to 98.60 mg/kg) and a exceedance rate of 95.0%; arsenic was commonly detected but there was no clear limit standard, while mercury and lead only exceed the limit in inedible parts such as crab gills; the overall heavy metal content was cadmium>arsenic>mercury>lead>chromium, and the content of edible parts (crab body meat, crab leg meat) was significantly lower than that of non edible parts; the heavy metal content in whole crabs was significantly affected by highly polluted areas such as the liver and pancreas. Conclusion Imported Cancer pagurus pose a high risk of cadmium enrichment in suspected edible parts such as the liver, pancreas and gonads. It is necessary to improve the definition criteria for edible parts and establish a targeted risk assessment mechanism. It is recommended that consumers reduce their intake of highly contaminated parts. This study provides data support for optimizing the safety supervision strategy and dietary guidance of imported crustacean aquatic products.

Objective To establish a method for the determination of 8 kinds of benzodiazepines residues, including diazepam, oxazepam, midazolam, clonazepam, lorazepam, triazolam, alprazolam and nitrazepam in aquatic products by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Methods The sample was extracted by 80% acetonitrile aqueous solution containing 0.2% formic acid, purified by Waters PRIME HLB solid phase extraction column, concentrated by nitrogen blowing in water bath. The residue contents were separated by C₁₈ chromatographic column, eluted by 0.1% formic acid aqueous solution-methanol mobile phase systems, and analyzed by electrospray ion source in positive ion multi-reaction monitoring mode. The quantitative information was obtained by matrix-added calibration with external standard. Results The correlation coefficient of calibration curves of 8 kinds of benzodiazepines residues were above 0.999. The limits of detection were 0.064-0.226 μg/kg, the recovery rates of the method were 70.4%-107.0%, and the relative standard deviations were 2.1%-10.2%. Conclusion The method is rapid, simple and accurate, and it is suitable for the determination of benzodiazepine sedative drug residues in aquatic products.

Tea is deeply loved by consumers for its unique aroma and health benefits, which is why tea quality and safety have garnered widespread attention. The quality and safety of tea involves the quality and safety of tea, as well as issues such as pesticide residues, heavy metals, harmful microorganisms, and fluorine. It is closely related to all aspects of tea cultivation, processing and storage. This paper started with tea-related standards and focuses on tea quality and safety issues such as pesticide residues, heavy metals, harmful microorganisms and fluoride, etc. It summarized the pretreatment of tea samples, normal detection technologies, rapid detecting methods, and relevant research progress. The aim is to provide a comprehensive knowledge framework for the tea industry, enhance quality and safety standards, and promote the sustainable development of the tea industry.