In recent years, mycotoxin contamination in food has become an important food safety issue with global concern. Mycotoxins are a type of secondary metabolites produced by fungi with characteristics of high toxicity, difficult decomposition and chemical stability. It is of great significance to establish an efficient and safe mycotoxin detoxification technology applicable to food. Based onenzyme catalysis, the biological detoxification technology has the advantages of high substrate specificity, mild conditions, green environment, which can overcome the damage of traditional physical and chemical detoxification technology to the quality and nutritional value of food. Immobilized enzyme technology can improve the catalytic performance of enzymes, endow them with values such as stability, reusability, and high throughput, as well as overcome the limitations of biological enzymes in the application process. This article reviewed the application of immobilized enzyme technology in food mycotoxin removal, analyzed the deficiencies of the current immobilized enzyme technology applied in food detoxification and possible future research directions, with a view to providing research ideas for the construction of more efficient immobilized enzyme catalysts.

Objective To investigate the induced expression level and enzymatic properties of recombinant bacterial laccase and to improve the degradation efficiency of sulfadiazine antibiotics by bacterial laccase. Methods In this study, the effects of induction temperature, induction time, and concentration of isopropyl β-D-thiogalactopyranoside (IPTG) on enzyme expression were investigated by one-way experiments. The enzymatic properties of recombinant bacterial laccase were also investigated by both pH and temperature. Results The degradation of sulfadiazine by recombinant bacterial laccase at 24 h was 50%. The optimal conditions for the expression of recombinant bacterial laccase in Escherichia coli BL21 (DE3) were as follows: Induction temperature of 16 ℃, induction time of 16 h, and IPTG concentration of 0.2 mmol/L. The optimal pH was 3, and the stability was best at pH 7, with the enzyme activity reaching 150% in 6 h. The optimal temperature was 80 ℃, and the thermal stability was best at 70 ℃, with the enzyme activity increasing to 120% in 1 h. The half-life was about 6 h. Conclusion This study provides an experimental basis for the application of bacterial laccase in the degradation of sulfadiazine antibiotics and lays down a theoretical basis for the future study of its potential application in the industry.

Objective To develop a colorimetric analysis method based on nanozymes, rapidly evaluate the total antioxidant capacity of wild edible mushrooms (Auricularia cornea, Flammulina filiformis, and Pleurotus ostreatus) in Yangzhou. Methods Nano silver modified manganous oxide (Mn/Ag NPs) nanozyme was prepared by the hydrothermal method, and its microstructure was confirmed by various characterization methods. The total antioxidant capacity of 3 kinds of wild edible mushrooms were extracted using different solvents, and their total antioxidant capacity were evaluated by the colorimetric analysis method based on Mn/Ag NPs nanozyme. In addition, the evaluation results were verified using the commercial 2,2’-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) kit. Results The colorimetric analysis method based on Mn/Ag NPs nanozyme achieved the rapid evaluation of the total antioxidant capacity of wild edible mushrooms in Yangzhou. Total antioxidant activity was Pleurotus ostreatus>Flammulina filiformis>Auricularia cornea. Extraction efficiency of solvent was ultrapure water>mixed solvent>ethanol>ethyl acetate. Conclusion The colorimetric analysis method based on Mn/Ag NPs nanozyme can rapidly evaluate the total antioxidant capacity of wild edible mushrooms in Yangzhou.

Excessive intake of fat in human body is the main cause of obesity and cardiovascular and cerebrovascular diseases. With the gradual enhancement of national health awareness, people gradually pay attention to fat substitutes with low calorie and low energy. Fat substitutes can not only meet people's sensory needs for color, fragrance and taste of food, but also reduce the intake of fat without changing the taste quality of food, which is of great significance to prevent various chronic diseases. Therefore, producing low-fat or fat-free food is an important way to improve people's eating habits and improve people's health. Fat substitutes are a kind of substances that mimic the fat in natural foods, which can be divided into 3 types: Fat substitutes (esterified derivatives of fatty acids, with almost zero digestibility in human body), fat simulators (carbohydrate fat simulators and protein fat simulators) and compound fat simulators. Fat substitutes can reduce the fat content in food, and more importantly, they can improve the oral sensory lubrication texture of food. This paper summarized the application and development prospect of fat substitutes in modern food research at home and abroad, in order to provide guidance for the research and development of low-calorie diet.

Objective To study the nutritional components of Weiying watermelon foranalyze and evaluate the nutritional quality of Weiying watermelon. Methods Namely “Meidu” watermelon from 2 main production areas of Weiying watermelon (S1 and S2) were used as experimental materials, and the same variety of watermelon from two other production areas (S3 and S4) as controls. The content of sugar, organic acid, amino acid, mineral, soluble solid, β-carotene, lycopene and vitamin C in the watermelons from the 4 production areas were detected and analyzed. Results The watermelon from different producing areas exhibited certain variations in quality characteristics. The sugar components in watermelon was mainly glucose and fructose, organic acids was mainly malic acid and lemon, free amino acids was mainly citrulline, and it also contains abundant mineral elements; the glucose content, sugar-acid ratio and sweetness-sourness ratio in S1 and S2 were higher than those in S3 and S4, while the total acid content was the opposite. In addition, the levels of the citrulline, β-carotene, lycopene and vitamin C in S1 and S2 were also higher than those in S3 and S4, respectively. The comprehensive performance of the nutritional quality of S1 and S2 were superior to that of S3 and S4 based on the principal component analysis. Conclusion Weiying watermelon has better flavor and texture, richer nutritional components, and superior nutritional quality.

Objective To isolate a strain of Listeria monocytogenes from frozen chicken meat sold in Gansu Province and analyze its serotype, antibiotic resistance phenotype, and genomic characteristics. Methods The slide agglutination method was used for serological identification, the broth microdilution method was used to analyze the sensitivity of the strain to 8 kinds of antibiotics, and the genomic characteristics were analyzed by sequencing. Results The strain was identified as Listeria monocytogenes by 16S rDNA species identification, with a 1/2a serotype, phylogenetic lineage II, subline SL 155, and clone CC 155 MLST 705, cgMLST 13240. Sensitive to 4 kinds of antibiotics including ampicillin, penicillin, vancomycin, and meropenem, and multidrug-resistant to 4 kinds of antibiotics including erythromycin, ciprofloxacin, tetracycline, and compound sulfamethoxazole. Simultaneously carrying aph(3')-III, ant(6)-Ia, dfrG, fosX, lnu(B), lsa(E), erm(B), tet(S) and tet(M) 9 kinds of resistance genes, carrying 5 virulence genes of LIPI-1, prfA gene deletion, carrying 12 kinds of internalization genes, no premature stop codon of inlA gene carrying, no LIPI-3, and LIPI-4. Conclusions The Listeria monocytogenes carries abundant virulence genes and resistance genes, and its resistance phenotype is basically consistent with the resistance genes, showing multiple drug resistance, providing a reference for the prevention and treatment of listeriosis.

Objective To elucidate the effects of flower of Changshan-huyou on the aroma profile of black tea. Methods This study employed solid phase microextraction-gas chromatography-tandem mass spectrometry (SPME-GC-MS) to differentially analyze the aroma components of flower of Changshan-huyou, Jiukeng black tea, and the derived Changshan-huyou scented tea. Results A total of 186 volatile compounds were identified in this paper, with 92, 78 and 67 kinds of volatile compounds detected in flower of Changshan-huyou, Jiukeng black tea and Changshan-huyou scented tea, respectively. The volatile composition of flower of Changshan-huyou was mainly characterised by alcohols and alkenes, whereas the volatile profiles of Jiukeng black tea and Changshan-huyou scented tea were mainly alcohol-rich. Nerolidol and linalool were found to be the predominant aroma components in Changshan-huyou scented tea, imparting a pronounced flora, fruity aroma and sweetness. Comparative analysis revealed an increase in alcohols and a concomitant decrease in alkenes in Changshan-huyou scented tea compared to flower of Changshan-huyou. Conversely, an increase in alkenes and a decrease in aldehydes were observed in Changshan-huyou scented tea compared to Jiukeng black tea. In addition, 32 kinds of unique compounds were identified in Changshan-huyou scented tea, which may be due to its unique processing techniques and the specific varieties of raw materials used. Conclusion The results of this research not only substantiate the aroma signature of Changshan-huyou scented tea, but also provide insights into its quality enhancement, paving the way for standardised production and innovative development strategies.

Objective To analyse the types and content of metabolites in the stems and leaves of Platycodon grandiflorus by ultra performance liquid chromatography-Quadrupole/Orbitrap high-resolution mass spectrometry (UPLC-Q/Orbitrap HRMS). Methods Stems and leaves of two-year-old purple flowered Platycodon grandiflorus from different sources was used as experimental materials. UPLC-Q/Orbitrap HRMS technology was used to analyze the extracts of Platycodon grandiflorus stems and leaves in negative ion mode, using orbitrap for MS1 full scan and data dependent acquisition ion trap for MS2 scan, and screen for differential metabolites of Platycodon grandiflorum stems and leaves from different sources. Results A total of 18 metabolites were detected in the stems and leaves of Platycodon grandiflorum, including 4 flavonoids, 2 alkynyl glycosides, and 12 saponins (1 metabolite that had not been reported). The basic structure of this unknown compound was polygalacic acid-glucose- xylose/arabic glycoside. Through comparative analysis, differences in chemical composition of Platycodon grandiflorus among different sources were discovered. The 6 differential metabolites of Platycodon grandiflorus from China and South Korea and 1 differential metabolite of Platycodon grandiflorus from Yanbian area were screened. Conclusion The comprehensive analysis results indicate that the stems and leaves of Platycodon grandiflorus have rich chemical components, and the stems and leaves of Platycodon grandiflorus from different sources have compound differences, which have high development and utilization prospects, providing theoretical basis for the development and utilization of aboveground resources of Platycodon grandiflorus.

Objective To investigate the feasibility of using the adenosine triphosphate (ATP) bioluminescence method for detecting the colonies number in chilled meat, and compare its performance with the national standard plate count method. Methods Effects of different concentrations of Triton X-100 and adenosine triphosphate double (Apyrase) on the remove of ATP from the somatic cells of chilled meat were determined. The colonies number in the chilled meat was measured using both the ATP bioluminescence method and the national standard plate count method, and the reproducibility of the ATP bioluminescence method was evaluated. Results The optimal concentrations of Triton X-100 and Apyrase for ATP removal from the somatic cells of chilled meat were found to be 0.2% and 0.10 U/mL, respectively, with the best ATP removal effect observed at these concentrations. The results of the ATP bioluminescence method and the national standard plate count method demonstrated a strong linear relationship, with a correlation coefficient (r²) of 0.9871. The ATP bioluminescence method indicated good reproducibility, and the results were stable and reliable. Conclusion This study further validates the applicability of ATP bioluminescence method for the quick detection of colonies number in chilled meat, demonstrating its advantages over the national standard plate count method.

Objective To establish a method for the determination of chlorophyll a and chlorophyll b content in vegetables by convergence chromatography (CC). Methods The Soxhlet extraction method was used for efficient extraction of chlorophyll from vegetables and their products, followed by separation and detection using an ultra-performance convergence chromatography system coupled with a ultraviolet-visible detector. Results Through comparison of the stability of different solvents, petroleum ether was selected as the extraction solvent, and the extraction conditions were optimized. The method was validated with a limit of detection of 0.02 mg/kg, a limit of quantification of 0.06 mg/kg, a linear range of 0.06-800.00 mg/kg, a spike recovery rate of 99%-102%, and a relative standard deviation of 2.2%-14.0% for real samples. The reliability and accuracy of the method were confirmed through precision testing of real samples, including kale, fresh mustard greens, pickled mustard greens, dried pickled mustard greens, steamed dried pickled mustard greens, and boiled dried pickled mustard greens, as well as cross-validation with existing standard methods. Conclusion This study establishes a CC-based method for detecting chlorophyll a and chlorophyll b in vegetables, demonstrating high sensitivity, a wide linear range, good specificity, and precision. The method is not only suitable for laboratory research but also has practical application potential.