Objective To establish a method for the simultaneous detection of hypoxanthine, guanine, xanthine, and adenine in edible fungi by high performance liquid chromatography, and use this method to the analysis of commercially available edible fungi. Methods The purines (hypoxanthine, guanine, xanthine, and adenine) from edible fungi were extracted by using acid hydrolysis. The chromatographic column was selected based on the resolution and peak shape of the 4 kinds of purines. Detection conditions, including the mobile phase ratio, flow rate, column temperature, and injection volume, were optimized, and the methodology was validated. Results The results showed that using Insert Sustain AQ-C₁₈ column with a mobile phase consisting of 50 mmol/L ammonium acetate solution (pH 4.0) and methanol (V:V=97:3), at a flow rate of 0.6 mL/min and the column temperature of 30 ℃, with an injection volume of 10 μL and detected at 254 nm, the 4 kinds of purines could be completely separated with good peak shapes. And the methodological validation results showed that this method exhibited a good linear relationship within the detected range. Conclusion A high performance liquid chromatography method is established through the optimization of detection conditions, which effectively differentiates and simultaneously detects the 4 kinds of purines in edible fungi. The content of hypoxanthine and xanthine (uric acid precursor substances) are very low or undetectable in the detected edible fungi. Based on the purine intake guidelines in the Encyclopedia of Chinese nutritional science, the dietary intake of the currently available commercial edible mushrooms is determined.

Food safety is a major strategic content related to people's livelihoods and achievement of the modernization of national governance. After the extensive scientific research and regulatory practice, many iconic academic achievements have been achieved, and the relatively systematic theoretical systems, methodological standards and regulatory strategies for food safety have been established. The traditional food safety mainly relies on the methodological development, safety detection and risk monitoring, depends on the laws, regulations, and standards as regulatory basis, utilizes propaganda, education, service and popularization of science as auxiliary means, and combine the rectification and improvement. Due to the complex interactions between humans and food, there are many characteristics involved in food safety like uncertainty, relativity and regionalism. At present, the connection between the food safety research and regulation is not close enough, and the food safety work still needs a lot of innovative exploration, practice and the new quality productivity empowerment. Based on the author's recent research, teaching, investigation, and regulatory practices in food safety, this paper started from the root causes of food safety issues, summarized and discussed the main challenges faced in the current food safety work from the perspective of the risk prevention and control throughout the entire process, and proposed the directions that could be focused on the food safety research, teaching and regulation in future, which would help achieving the precise prevention and control of food safety across the entire region.

Objective To develop a comprehensive evaluation method for the quality of Anji white tea and explore its grading criteria. Methods A sensory evaluation and quality component analysis were conducted on 30 samples of Anji white tea. A quality evaluation model for Anji white tea was established using methods such as correlation analysis, principal component analysis, entropy weight method, and grey correlation analysis. Results The results indicated significant differences (P<0.05) in chemical indicators among Anji white tea from different sources. Moreover, there was a significant correlation (P<0.01) between total catechins, general flavone, and alkaloid components. The comprehensive evaluation model constructed using the entropy weight method and grey correlation analysis could reliably reflect the sensory quality characteristics of Anji white tea, and the fit of its regression model was as high as 0.8258. Furthermore, a grading method for Anji white tea was proposed based on cluster analysis of relative relevance, resulting in effective classification into 4 grades. Conclusion The quality evaluation model established based on entropy weight method combined with gray correlation analysis has achieved the classification of quality grades of Anji white tea and also provides reference and guidance for the quality evaluation of other types of tea.

Objective To establish a rapid method for the determination of 5 kinds of nucleotides (cytidine-5’-monophosphate, adenosine-5’-monophosphate, uridine-5’-monophosphate, guanosine-5’-monophosphate and inosine-5’-monophosphate) in infant formulas and dairy products is developed based on mixed-mode hydrophilic interaction/ion exchange chromatography-ultraviolet detection (HILIC/IEX-UV). Methods A zwitterionic hydrophilic interaction chromatography column (Alphasil S-Xion) was used, with mobile phase consisting of 5 mmol/L KH₂PO₄ (pH adjusted to 3.0 with H₃PO₄)-acetonitrile (70:30, V:V) to detect nucleotides in infant foods and dairy products. Results The five nucleotides were baseline separated within 10 min, demonstrating efficient chromatographic performance. They exhibited good linearity within the range of 2-50 μg/mL, with limits of detection (LODs) between 0.19 and 0.66 mg/kg, and limits of quantification (LOQs) ranging from 0.62 to 2.19 mg/kg. At spiked levels of 50, 100 and 200 mg/kg, the intraday recoveries ranged from 96.6% to 108.9%, with relative standard deviations (RSDs) of 1.5%-6.3%, while the interday recoveries were between 101.0% and 108.0%, with RSDs of 2.4%-7.3%. Conclusions Compared with the traditional reversed-phase ion-pair chromatography, this method has significant advantages: Effectively reducing the matrix interference, shortening the analysis time, improving the detection efficiency, and especially improving the quantitative accuracy of cytidine-5’-monophosphate. The proposed method is rapid, accurate, and anti-interference, which provides technical support for the efficient analysis of nucleotides in infant formulas and dairy products.

Objective To study the characteristics of volatile flavor substances in beef jerky products processed by different processing methods. Methods Beef was processed by different processing methods (15 kinds of curing, bacterial curing, air-drying, etc.), and analyzed by headspace solid-phase microextraction combined with comprehensive two-dimensional gas chromatography-time of flight mass spectrometry. Results The differential metabolites in 15 kinds of samples were detected. Among them, during the pickling process of Staphylococcus xylosus, Lactobacillus plantarum and Pediococcus pentosaceus, the significant differential metabolites included 12 kinds of sugars, acids and esters. The cured beef processed by air-drying method and the cured beef with bacteria produced 8 kinds of extremely significant different metabolites such as maltose, decanoic acid and orotic acid after air-drying. More than 11 kinds of differential metabolites including naphthalene, 3-hydroxy-DL-norvaline, L-menthone, n-decanoic acid, D-pinobiose and myristic acid were detected in the cured beef processed by normal baking than in the cured beef processed by vacuum baking. The metabolic pathways involved in vacuum baking were citric acid cycle, alanine, aspartic acid and glutamic acid metabolism, and the metabolic pathways involved in baking were amino sugar and nucleotide sugar metabolism. Conclusion In this study, the changes of volatile flavor substances in beef jerky products with different processing methods are analyzed, which provide methodological guidance for improving the quality and taste of air-drying beef.

Extruded rice noodles are made from rice as raw material, ground and blended to a certain moisture content, extruded and matured, and dried. The traditional production process of rice noodles is laborious and time-consuming, which lead to uneven product quality during the multi-step rice noodle production process. By comparison, extrusion technology is a food processing technique that integrates mixing, heating, sterilization, and shaping. Applying extrusion technology to rice noodle processing has the advantages of less loss of nutrients, fewer opportunities for microbial contamination, shorter production time, higher production efficiency, and easier operation. Therefore, in the production of rice noodle processing industry in China, automated mechanical processing is gradually replacing traditional manual workshops. The quality of extruded rice noodles is mainly affected by the raw materials, processing technology, and extrusion parameters during the production process of extruded rice noodles. Therefore, this paper elaborated on the processing technology and forming mechanism of extruded rice noodles, summarized the influence of raw materials and extrusion parameters on the quality of extruded rice noodles, in order to provide theoretical basis for the control of the processing technology and key points of extruded rice noodles.

Objective To compare the differences in the quality indicators for ediable and medicinal of different strains of Polygonatum kingianum, and conduct a comprehensive evaluation. Methods The rhizome of 3 strains of Polygonatum kingianum, including the strain of Polygonatum kingianum with white flower and green stem (PKW), the strain of Polygonatum kingianum with purple flower and green stem (PKP) and the strain of Polygonatum kingianum with red flower and purple stem (PKR), were used as experiments materials. The differences of the content of nutrient, mineral elements and the main active ingredients was analyzed, the study on comprehensive quality evaluation research was conducted based on the membership function and principal component analysis methods. Results There were significant differences in 19 quality indicators between different strains of Polygonatum kingianum. PKW had the highest content of crude protein, total starch, crude fat, Na, polysaccharides and total flavonoids, PKP had the highest content of 10 kinds of mineral elements (K, P, Ca, Mg, Al, Mn, Fe, Zn, B and Cu) and total phenols, PKR had the highest content of moisture and total saponins. Pearson correlation analysis indicated that active ingredients showed a significant correlation with mineral elements and nutrient (P<0.05 or P<0.01); however, there was no significant correlation between nutrient and mineral elements. The analysis results were obtained by using the membership function method suggested that the highest scores of food and medicinal values were PKP and PKW respectively. The principal component analysis of 19 quality indicators were carried out, and the cumulative contribution of the 3 principal components was 96.41%. The evaluation results showed that PKP had the highest comprehensive score. Conclusion The medicinal value of PKW is the highest. PKP has comprehensive high quality, is suitable for both ediable and medicinal.

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 the determination of migration of isosorbide in isosorbide modified polyethylene terephthalate (PET) products by gas chromatography-flame ionization detector (GC-FID). Methods The effects of different chromatographic conditions on the separation of isosorbide were investigated. HP-5 was selected as the separation column and 260 ℃ was selected as the injection port temperature. The effects of different pretreatment methods on the extraction of isosorbide from food simulants were investigated. The olive oil food simulant was extracted with methanol, purified with n-hexane and filtered before analyzed. The 95% ethanol and isooctane simulants were directly analyzed by the machine after filtered. Other food simulants were diluted with methanol and then directly analyzed by the machine. The external standard method was used for quantification. Results Isosorbide had a good linear relationship in the range of 2.5-40.0 mg/L (aqueous food simulants), 0.6-10.0 mg/L (substitute simulants) and 1.5-25.0 mg/kg (fatty food simulants), and the correlation coefficient was above 0.995. The limit of detection of this method for the migration of isosorbide was 0.8 mg/kg (aqueous food simulants), 0.2 mg/kg (substitute simulants) and 0.5 mg/kg (fatty food simulants). The limit of quantification was 2.5 mg/kg (aqueous food simulants), 0.6 mg/kg (substitute simulants) and 1.5 mg/kg (fatty food simulants). The spiked recoveries were 92.0%-112.3%, and the relative standard deviation was 0.2%-4.3% (n=6). Conclusions This method has good linearity, high precision, sensitivity and accuracy, and can meet the detection requirements of isosorbide migration in modified PET products.

Fermented vegetables are considered one of the most nutritious and beneficial foods for health. The research in the microbial community structure is a great significance to explore the dominant strain resources and improve the flavor quality of fermented vegetables. This paper summarized the application of the next-generation sequencing technology on microbial community of fermented vegetables. Some analysis methods were emphatically introduced involving with microbial community succession, Alpha diversity analysis, Beta diversity analysis, functional annotation (Kyoto Encyclopedia of Genes and Genomes metabolic pathway annotation, cluster of orthologous group annotation, gene ontology annotation), network and correlation analysis of environmental factors. Based on the research progress, this paper suggests implement combined application among the next-generation sequencing technology and multiple omics technology including transcriptomics, proteomics, metabolomics. The correlation between microbial function with color, flavor and texture of fermented vegetables should be investigated. The new strain resources with fermenting high-quality vegetables should be screened and obtained. It provides a theoretical basis for the transformation of traditional fermented vegetables to standardization, industrialization and modernization in China.