Objective To understand the residual levels of semicarbazide in crustacean aquatic products such as shrimp and crabs, analyze the causes of endogenous and exogenous contamination. Methods Data from nationwide sampling inspections of crustacean aquatic products from 2017 to 2023 were analyzed. A total of 178 batches of shrimp, 136 batches of crabs, and aquaculture pond water samples were collected and tested. The quantitative determination was conducted following the standard of Ministry of Agriculture Announcement No.783-1-2006 Determination of nitrofuran metabolite residues in aquatic products. Results The detection level of semicarbazide in crabs was significantly lower than that in shrimp. The semicarbazide levels in crabs showed little correlation with species, while significant variations were observed among different shrimp species. No semicarbazide residues were detected in aquaculture pond water. Conclusion The presence of semicarbazide in crustacean aquatic products such as shrimp and crabs is primarily related to endogenous sources, though the detected levels from endogenous origins are very low. It is recommended that national authorities resume routine supervision and sampling inspections for nitrofurazone metabolites in crustacean products, establish a national database for semicarbazide monitoring, and utilize big data analysis to address current policy gaps. Furthermore, based on the analysis of the national database, efforts should be made to develop semicarbazide residue limit standards for crustacean aquatic products to ensure the healthy development of the aquaculture industry.

Objective To establish a method for the simultaneous determination of fasciolicides and its metabolite (nitroxinil, rafoxanide, closantel, triclabendazole and ketotriclabendazole) in raw milk by QuEChERS coupled with ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Methods The raw milk samples was extracted with 3% triethylamine acetonitrile-ethyl acetate acetate solution (7:3, V:V), purified by C₁₈ adsorbent powder, and determined by UPLC-MS/MS with external standard method. The chromatographic separation was performed on an ZORBAX Eclipse Plus C₁₈ (2.1 mm×100 mm 1.8 μm) column with a mobile phase of 0.1% formic acid-acetonitrile solution, and detected under multiple reaction monitoring (MRM) mode in the positive and negative electrospray ion modes. Results The results showed that a good linear relationship was obtained in the mass concentration range of 1 to 100 μg/L for fasciolicides and its metabolite, and the correlation coefficients (r) were all greater than 0.9988, the limits of detection were 2.5 μg/kg, and the limits of quantitation were 5 μg/kg. The average recoveries of 5 kinds of compounds at the concentration levels of 10, 20 and 100 μg/kg were between 86.0% and 108.2%, and the relative standard deviation ranged from 0.81% to 5.60%. Conclusion The method is simple, rapid accurate and reliable, and is suitable for the rapid determination of the residues of fasciolicides and its metabolite in raw milk.

Objective To analyze the cause of a complex food poisoning incident using a combination of non-targeted and targeted methods based on mass spectrometry. Methods Suspected contaminated food and blood samples from the cases were collected. After sample preparation, a high-resolution mass spectrometry non-targeted method was used for toxin screening, and a triple quadrupole mass spectrometry targeted detection method was applied for the quantitative analysis of xylazine in the samples. Results Xylazine was detected in both the suspected contaminated food (raw and fried venison) and the serum samples of 3 cases. The concentrations in raw and fried venison were 3.0 μg/kg and 395.9 μg/kg, while the concentrations in the cases’ serum were 47.0, 16.0 and 15.6 ng/mL, respectively. Conclusion This incident is confirmed as xylazine poisoning caused by venison ingestion. First, through epidemiological investigation, the scope for identifying the cause of poisoning can be quickly determined. The non-targeted method provides accurate evidence for clinical treatment, aiding in the diagnosis and management of such events. At the same time, the targeted quantitative analysis of samples also provides a basis for the formulation of drug use standards in farmed animals in the future.

Objective To construct a predictive model for bacterial growth in braised chicken legs under variable temperature conditions during actual circulation. Methods Based on the one-step method of the Huang model, the growth process of foodborne Escherichia coli (E. coli) in braised chicken legs was studied. Kinetic parameters for E. coli growth and survival were determined through multiple sets of isothermal experiments, ultimately yielding a second-order model describing the relationship between instantaneous colony count, temperature, time and initial colony count. The model was validated using simulation experiments. Results A significance analysis of differences was conducted between the measured growth colony counts of E. coli strains cultured under fluctuating temperatures and the predicted colony counts obtained by the model. The test showed that P=0.926>0.05, indicated that there was no significant difference between the predicted values and the measured values. Conclusion The second-order model constructed in this study can effectively simulate E. coli growth under fluctuating temperatures and is sufficiently reliable. The model, integrated with the R programming language, allows for rapid prediction of E. coli growth under fluctuating temperature conditions, providing a rapid and effective tool for risk assessment of braised meat products in actual circulation.

Objective To explore the bacterial community composition and abundance, as well as inter-sample variations in species composition and community structure in commercially available peanut butter and sesame paste sold in Yunnan Province using 16S rRNA gene sequence analysis. Methods A total of 160 samples encompassing best-selling peanut butter, sesame paste, and mixed spreads from Yunnan Province were subjected to 16S rRNA V4 region amplicon sequencing. Subsequent analyses included species composition profiling, abundance clustering, phylogenetic relationships, and diversity assessments. Results Characteristic sequence analysis revealed that sesame paste contained the highest number of characteristic sequences, followed by peanut butter, while mixed paste had the least. Bacterial community composition analysis indicated that these unique sequences predominantly belonged to the phyla Proteobacteria, Cyanobacteria and Firmicutes. At the genus level, the top 35 identified genera included Listeria, Escherichia-Shigella, Clostridium_sensu_stricto_1, Bacillus, Vibrio, Streptococcus, Pseudomonas and Aeromonas. α diversity analysis demonstrated significant differences in species diversity between peanut butter and sesame paste (P<0.05). Conclusion Distinct bacterial compositions are observed among peanut butter, sesame paste, and mixed spreads, with sesame paste exhibiting the highest species abundance. Among the top 35 identified genera, 12 are known to include pathogenic species, posing potential food safety risks. It is imperative for manufacturers and regulatory authorities to address these concerns to ensure consumer safety. This study provides a reference for food safety regulatory authorities and offered important data support for the establishment of microbiological safety standards for nut butter products.

Objective To develop for the determination of 16 kinds of rare earth elements in plant agricultural products by micro-open graphite digestion coupled with inductively coupled plasma mass spectrometry. Methods Using the micro-open graphite digestion as the pretreatment method, the effects of acid digestion system, digestion time and matrix elements (K⁺, Na⁺, Ca²⁺, Mg²⁺, Fe²⁺, Cu²⁺, Zn²⁺, Mn²⁺) on rare earth elements were investigated. Results The results showed that adding HF to the HNO₃+HClO₄ mixed acid system facilitated complete digestion of samples and significantly improved the recovery of rare earth elements. When the concentration ratio of matrix elements to rare earth elements reached 4 orders of magnitude, there was no significant interference in the determination of rare earth elements. Under optimal conditions, the standard curves exhibited good linear relationships (r≥0.999) in the range of 0-50 μg/L, with the limits of detection was 0.001-0.006 mg/kg. The method was validated using national standard reference materials, and the determination results of each rare earth element were generally consistent with the reference values. The recoveries of spiked samples were 83.2%-110.3% and the relative standard deviations were 1.0%-10.4%. Conclusion The method features simple operation, strong anti-interference capability, and high accuracy, making it suitable for rapid determination of rare earth elements in batch plant agricultural products.

Objective To investigate the effects of repeated freeze-thaw cycles, induced by temperature fluctuations during cold chain circulation, on the quality deterioration of pre-prepared grilled fish. Methods An accelerated deterioration model was established through extreme treatment to examine the effects of up to 8 freeze-thaw cycles on microstructure, texture properties, pH, color parameters and lipid oxidation. Correlation analysis was conducted to identify the primary factors contributing to quality degradation. Results As the number of freeze-thaw cycles increased, muscle tissue damage intensified, myofibril structures fractured, and hardness, elasticity, chewiness and shear force declined, while adhesiveness increased. The pH value showed a decreasing-then-increasing trend. Overall, the lightness value (L^*) progressively decreased, while the redness (a^*) and yellowness (b^*) values continuously increased. The thiobarbituric acid reactive substances (TBARS) value significantly increased from 0.28 mg/kg to 2.00 mg/kg (P<0.05). After 6 cycles, the total volatile basic nitrogen (TVB-N) content exceeded the national safety limit for consumption (27.43 mg/100 g, national standard limit≤25 mg/100 g). Conclusion The quality of pre-cooked grilled fish significantly deteriorates during distribution, and the damage becomes more severe with increasing freeze-thaw cycles. After more than 5 cycles, the product is no longer suitable for consumption. These findings provide a scientific basis for quality control strategies in the cold chain logistics of pre-prepared aquatic products.

The frequent occurrence of adulteration in meat products not only affects people's quality of life but also restricts the healthy development of the industry. The technology of identifying adulteration in meat products has become a research hotspot. Fast, accurate, reliable, and simple meat ingredient detection technology is an effective means of identifying adulteration in meat products This article reviewed the principles, advantages, disadvantages and application research of various meat source component detection technologies that had been extensively studied, including spectroscopic technology, chromatographic and mass spectrometry analysis technology, immunoassay technology and isothermal amplification analysis technology. It also looked forward to the future research directions of these technologies, in order to provide theoretical basis and reference ideas for the research of meat product adulteration identification technology.

Objective To optimize the mixed acid extraction process of pectin from Akebia trifoliate peel and evaluate the structure, and antioxidant properties of pectin. Methods Using Akebia trifoliate peel as raw material, which was extracted by the mixed acids hydrolysis. The effects of the types of inorganic acids, the volume ratio of the mixed acid, solid-to-liquid ratio, pH, extraction time and temperature were studied, and Box-Behnken response surface method was used to optimize the extraction process parameters on the basis of single factor experiment. The structure of the peel pectin of Akebia trifoliate obtained under the optimal extraction conditions was characterized by ultraviolet-visible spectroscopy (UV-Vis) and Fourier transform infrared spectroscopy (FT-IR), and its antioxidant activity was investigated. Results The optimal extraction conditions were: The volume ratio of the mixed acid [V(citric acid):V(sulfuric acid)] 2:1, solid-to-liquid ratio 1:30 (g:mL), pH value 1.0, extraction time 2.0 h and temperature 94 ℃, and the extraction rate reached 14.22%, which were about 1.24% and 4.17% increase compared with single sulfuric acid and citric acid, respectively. FT-IR showed that the absorption peaks of sulfuric acid and citric acid extraction of pectin (CSEP) were more consistent with its structural characteristics than sulfuric acid extraction of pectin (SEP) and citric acid extraction of pectin (CEP) at 1754 cm^-1 and 1624 cm^-1, and its content of galacturonic acid (81.94%) and degree of esterification (82.41%) more higher. CSEP own superior antioxidant biological activity, and the half maximal inhibitory concentration (IC₅₀) for hydroxyl radical of CSEP was lower than that of commercial pectin (CP), which were 2.248 mg/mL and 4.114 mg/mL, respectively. Conclusion Using the mixed acid to extract pectin from Akebia trifoliata peel has good improved on extraction rate, content of galacturonic acid and antioxidant activity.

Objective To study the preparation and physicochemical properties of polypeptide-selenium chelate from Juglans regia L.. Methods Juglans regia L. protein was extracted by alkali-soluble acid precipitation method, and Juglans regia L. polypeptide was prepared by alkaline protease. Juglans regia L. polypeptide reacted with sodium selenite to produce Juglans regia L. polypeptide-selenium chelate. The preparation technology was optimized by single factor test and orthogonal test. Results When the mass ratio of polypeptide to sodium selenite was 3:1, the chelating temperature was 45 ℃, the chelating time was 50 min, and the pH was 8, the chelating rate was 58.99%±1.44%. The chelate was resistant to heat, acid and alkali, had good digestive stability and high bioavailability of selenium. Compared with Juglans regia L. polypeptide, Juglans regia L. polypeptide-selenium chelate had stronger scavenging ability of 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical, hydroxyl free radical and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) cation free radical. Conclusion In this study, Juglans regia L. polypeptide-selenium chelate is successfully prepared through optimized synthesis conditions. The resulting complex demonstrates favorable physicochemical properties and significant antioxidant capacity, providing a potential raw material reference for developing selenium-enriched nutritional supplements.