Objective To synthesize a Au-Pt bimetallic nanozymes (Au-PtNFs) with oxidase and peroxidase dual-enzyme activity, and apply them in detection of organophosphorus pesticide. Methods The 3 kinds of Au-PtNFs were prepared through seed-mediated method by adjusting the amount of chloroplatinic acid, and their enzyme activities were determined using 3,3’,5,5’-tetramethylbenzidine (TMB) as the substrate. The nanozyme exhibiting the highest enzyme activity was selected and combined with the catalytic effect of acetylcholinesterase to establish a detection method for organophosphorus pesticide. Results The 3 kinds of prepared nanozymes all had flower-like structures, and the particle size enhanced with the increasement of chloroplatinic acid concentration. Steady-state dynamic experiments showed that all bimetallic nanozymes had dual-enzyme activity, and the best enzyme activity was obtained when the concentration of chloroplatinic acid was 5 mmol/L. Absorption at 620 nm exhibited a good linear correlation with the logarithm of chlorpyrifos concentration in the range of 40-90 nmol/L, and the limit of detection was 1.00 nmol/L. The method demonstrated excellent specificity and anti-interference ability, and achieved great recovery rate in real samples. Color value analysis software was used for the detection of chlorpyrifos based on smartphone. The linear range was 30-100 nmol/L and the limit of detection was 1.06 nmol/L. Conclusion The prepared Au-PtNFs exhibiting dual-enzyme activity are effectively utilized for detection of organophosphorus pesticides, which offers a novel perspective for visual detection of organophosphorus pesticides in fruits and vegetables.

Objective To establish a highly sensitive analytical method for the determination of advantame in alcoholic beverages by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Methods The wine samples were diluted 10 times with ultrapure water, filtered through a membrane, and then injected. A Kinetex^® Biphenyl 100 Å chromatographic column (100 mm×3.0 mm, 2.6 μm) was used, with water and methanol as the mobile phase for gradient elution and separation. An electrospray ionization source (ESI) was adopted for detection in the positive ion scan multiple reaction monitoring (+MRM) mode, and external standard method was used for quantification. Results Advantame exhibited an excellent linear relationship within the mass concentration range of 0.03 to 40.00 μg/L, with a correlation coefficient of 0.9999. The limit of detection was 0.10 μg/kg, the limit of quantification was 0.30 μg/kg. The average recoveries at the 4 different spiked levels of low, medium-low, medium-high and high were 80.8% to 109.8%, and the relative standard deviation was 2.7% to 12.5% (n=6). Conclusion This method has high detection sensitivity, is simple to operate, accurate and reliable, and can be used for the trace analysis and risk assessment of advantame in alcoholic foods, providing strong technical support for scientific supervision of the alcoholic beverage market.

Objective To explore the types and contents of amino acids in Asparagus from different sources. Methods Post-column ninhydrin-derived photometry was established to determine the species and contents of amino acids in Guangxi, Neijiang and southwest winter, and performed data analysis using stoichiometry. Results The average amino acid content in Neijiang was 3.06%, 3.53% in Guangxi, and 5.73% in southwest China. The amino acid composition and content in Neijiang and Guangxi were similar, and the content was uniform among different batches, the amino acid content in southwest and southwest was quite different from the first two sources, and the different batches were quite different. Conclusion This research provides scientific reference for quality evaluation of Asparagus and the study of its authenticity.

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 analyze the changes in microbial content of fresh cut Citrullus lanatus of different varieties over time under normal temperature and refrigeration storage conditions. Methods The 30 batches of 420 samples of the more popular of Kirin, Sweet King, and Black Beauty Citrullus lanatus, were selected as the research objects. After being divided and stored at room temperature and refrigerated conditions for 2, 4, 6, 8, 10, 12, and 24 hours, microbial item detection was carried out to obtain the total bacterial count, coliform count, mold and yeast count, and Staphylococcus aureus microbial contamination. Results The total bacterial count, coliform count, mold and yeast count of the three fresh cut Citrullus lanatus increased with storage time. After being stored at room temperature for 8, 10 and 12 hours, the total bacterial count of Kirin, Sweet King, and Black Beauty Citrullus lanatus exceeded 10⁵ CFU/g, the coliform count exceeded 100 CFU/g after 8 hours, and the total number of mold and yeast count exceeded 100 CFU/g after 10 hours, under refrigeration conditions, the average total bacterial count of Kirin, Sweet King, and Black Beauty Citrullus lanatus stored for 8 hours exceeded 10⁴ CFU/g; the coliform count, total number of molds and yeasts all exceeded 100 CFU/g after 10 hours of storage. Staphylococcus aureus was detected after 4 hours of storage at room temperature and 6 hours of refrigeration, with a total detection rate of 32.86%. Conclusion Fresh cut Citrullus lanatus pose an increased safety risk due to microbial contamination after being stored at room temperature for 8 hours. Consumers should consume them as soon as possible after purchase and store them at low temperatures if necessary.

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.

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 Microorganisms are significant factors affecting food safety. Contamination of food by microorganisms can lead to spoilage and deterioration, resulting in substantial economic losses. Moreover, many microorganisms possess pathogenicity, and the toxins they secrete are the main cause of foodborne diseases. Therefore, microbiological testing of food has important sanitary and social significance. With the development of the food industry, traditional plate separation methods, due to their long detection times and complex operations, are increasingly unable to meet the current demand for rapid testing. microbiological test tablets are a new type of detection tool, with the advantages of easy operation, no need for culture medium preparation, and space-saving in detection. In recent years, researchers have conducted extensive studies on test tablets for different microorganisms. This article organizes these studies, thoroughly combs the composition and principles of test tablets, analyzes their advantages and existing problems, and has certain theoretical value and practical guidance significance. It is hoped to provide some ideas for the research of microbiological test tablets.

Objective To develop a rapid method for detecting Salmonella, Escherichia coli O157, Listeria monocytogenes, Staphylococcus aureus, and Vibrio parahaemolyticus using multiplex polymerase chain reaction (PCR) and capillary electrophoresis technology. Methods Specific multiplex PCR primers were designed using conserved pathogenic genes of 5 kinds of foodborne pathogens, and the products were analyzed using capillary electrophoresis imaging. By optimizing the PCR reaction and electrophoresis conditions, a multiplex PCR capillary electrophoresis detection method was established. The specificity and sensitivity were studied as well. Results The specificity of the 5 pairs of primers was acceptable and no non-specific amplification occurred. The optimal primer concentration for multiplex PCR reaction was 0.2 μmol/L, and the optimal annealing temperature was 56.0 ℃. The optimal separation mode for capillary electrophoresis was AM900. The method had a high sensitivity, and the detection sensitivity could reach 5×10^-3 ng/μL. Conclusion The multiplex PCR capillary electrophoresis method for detecting 5 kinds of foodborne pathogens established in this study is simple for operation with high specificity and sensitivity, and can be very practical in detection of foodborne pathogens.

Aquatic products, as a significant source of high-quality animal protein, play a crucial role in the fishery economy of China. The aquatic product processing industry not only enhances the prosperity of this sector but also fosters the development of related industries, thereby serving as a vital link in the comprehensive advancement of fisheries. The standard system for aquatic product processing serves as the foundational institution for ensuring the high-quality development of China’s fishery industry. Enhancing the construction of the aquatic product processing system, refining the standard system, and fostering the healthy development of the aquatic product processing industry hold immense significance in safeguarding the quality and safety of aquatic products in China. This paper examined the current status of the standard system for aquatic product processing in China and proposes ideas, principles, and frameworks for its establishment. It was recommended that emphasis be placed on the coordinated development of an integrated industrial chain processing standard system while prioritizing quality evaluation methods for aquatic products. Furthermore, it was essential to expedite the formulation of standards encompassing general applicability, product quality grading and detection methodologies, processing quality control management and traceability protocols, storage and preservation practices, as well as cold chain logistics. These efforts aim to facilitate effective alignment between standards across both upstream and downstream segments of the industrial chain and provide standardized support for fostering sustainable growth within China’s aquatic product processing industry.