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.

Objective To investigate the drug resistance, biofilm formation ability, and molecular characteristics of methicillin-resistant Staphylococcus aureus (MRSA) isolated from food and clinical samples. Methods A total of 21 MRSA strains isolated from commercial food and 30 MRSA strains isolated from clinical cases in a Class 3 Grade A hospital in Shaanxi from 2019 to 2020 were tested for drug susceptibility, MLST, spa, SCCmec typing, and biofilm formation ability. The phylogenetic analysis of strains from different sources was performed based on SNP by whole genome sequencing. Results The resistance rates of 51 MRSA strains to penicillin, oxacillin, erythromycin, clindamycin, tetracycline, and other antibiotics exceeded 50%. Penicillin and oxacillin exhibited the highest resistance rates (100%), followed by erythromycin, clindamycin, and tetracycline with resistance rates of 98.04%, 96.08%, and 52.94% respectively. The ST59-t437-IVa(2B) molecular type was predominant among 21 food MRSA strains and 30 clinical MRSA strains, accounting for 52.38% (11/21) and 36.67% (11/30), respectively. Among the 21 food-borne MRSA strains, 38.09% (8/21) exhibited the capacity for biofilm formation, while all 30 clinical MRSA strains demonstrated biofilm-forming ability. The phylogenetic analysis revealed that ST59-t437-IVa(2B) constituted the primary evolutionary lineage of MRSA strains isolated from both food and clinical samples, with some strains from these two sources falling within the same evolutionary branch. Conclusion The drug-resistant types and rates of drug resistance in MRSA strains isolated from both food and clinical sources exhibited a high degree of consistency in this study. Moreover, the biofilm formation ability was found to be stronger in clinical MRSA isolates compared to those derived from food-borne sources. Additionally, close genetic relationships were observed between certain MRSA strains obtained from both food and clinical samples, highlighting the significance of further research and attention towards the risk posed by food-borne MRSA.

Objective To compare three domestic and foreign Cronobacter detection methods, for verifying the actual detection performance of three standard methods: GB 4789.40—2016 National standard for food safety food-Microbiology tests Cronobacter spp. (Enterobacter sakazakii) test, GB 4789.40—2024 National standard for food safety food-Microbiology tests Cronobacter test and ISO 22964—2017 Food chain microbiology-Horizontal detection methods for Cronobacter spp. Methods Three standard methods were used to detect Cronobacter in 403 samples collected from 2020 to 2022, including infant formula, cereal-based infant supplements, corn ingredients, and raw and supplemental ingredients of infant formula, and to test Cronobacter isolates for drug susceptibility. Results The total contamination rate of Cronobacter in 403 samples was 17.9% (72/403), and the contamination rates of corn raw material, cereal-based infant supplement and infant formula were 37.3% (38/102), 23.4% (33/141) and 1.0% (1/100), respectively. Although there was no significant difference in the total detection rate among the three standard methods (χ²=3.601, P=0.170), 41.5 ℃ could effectively improve the detection rate compared with 44 ℃ (χ²=18.813, P=0.000). The resistance rate of 72 strains of Cronobacter was 55.6% (40/72), among which the resistance rates of cefazolin, ampicillin, and amoxicillin/clavulanic acid were 52.8% (38/72), 5.6% (4/72), and 1.4% (1/72), respectively. Conclusion This study shows that GB 4789.40—2024 has reached the level of the international relevant methods, providing data support for the mutual recognition of the test results of GB 4789.40 and ISO 22964 methods. Cronobacter has high resistance to cefazolin, which should be avoided when choosing antibiotics for clinical treatment.

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.

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.

Objective To study the suitability of different varieties of Dioscorea esculenta for vacuum frying. Methods Nineteen varieties of Dioscorea esculenta widely cultivated in China were taken as raw materials. Six quality indexes of fried Dioscorea esculenta chips, namely the yield rate, sensory score, breaking force, adhesiveness, color difference, oil content and flavor, were measured, and difference analysis was carried out. Correlation analysis, principal component analysis, stepwise regression analysis methods were applied to explore the model fitting degree and the significance of the regression model. K-means clustering analysis method was used to preliminarily divide the processing suitability of the 19 Dioscorea esculenta varieties. Results Differences were found in the shape, size and color of fried Dioscorea esculenta chips among the 19 Dioscorea esculenta varieties, and correlations existed among the indexes. Taking the yield rate of Dioscorea esculenta (X₁), color difference value L^* (X₂), sensory score (X₃), breaking force (X₄), adhesiveness (X₅) and oil content (X₆) as the initial independent variables, principal component analysis could be conducted and a quality evaluation model for fried Dioscorea esculenta chips was constructed, which was Y=1.02-3.37X₁-0.19X₂+0.16X₃+0.18X₄+3.01X₅+2.43X₆. Among the 19 varieties, Zhan Shu 12, Mian Zi 12, Bai Shu, Chuan Zi Shu No. 6 and 317 were suitable for making chips; Yu Shu 27, Xu Yu No. 31, Qian Zi Shu No. 1, Wan Shu No. 5, Xiang Shu 98, Yu Shu 17, Zi Yun Hong Shu, Yu Shu 198, Qian Shu No. 8, Shang Shu 19, Kao Shu, Yu Shu 9 and Long Shu 9 were basically suitable for making chips; while Tong Shu No. 2 was not suitable for making chips. Conclusion The research results can be referred to when the Dioscorea esculenta industry in China selects specific varieties for chip processing.

Objective To delve into the influences of slightly acidic electrolyzed water (SAEW) and ultra-high pressure (UHP) on the bactericidal potency of Panax notoginseng tubers, and quantification of synergistic bactericidal effect, constructing bactericidal model. Methods Fresh Panax notoginseng was selected as the raw material, with independent variables encompassing SAEW available chlorine concentrations (25, 30, 35 mg/L), solid-liquid ratios (1:20, 1:30, 1:40 g/mL), treatment durations (4, 6, 8 min), and pressures (200, 300, 400 MPa). The number of deceased Escherichia coli on the surface of Panax notoginseng tubers was set as the response value. A response surface methodology was adopted to optimize these treatment parameters and establish a coordination range for parallel SAEW-UHP treatments while quantifying their synergistic effects, verified the prediction accuracy of the model. Results Revealed that based on single-factor experiments, SAEW-UHP parallel technology was better than single technology in bactericidal effect, the optimal sterilization process parameters for the SAEW-UHP parallel technology lie within a solid-liquid ratio range of 1:26.90-1:33.34 g/mL, available chlorine concentrations range of 29.03-35.00 mg/L, treatment durations range of 5.27-6.83 min, pressure range of 295.57-400.00 MPa and the material-to-liquid ratio was set at 1:31.28 g/mL, with an electrolyzed water concentration was set at 34.25 mg/L, treatment duration was set at 6.79 min, and the pressure was set at 400.00 MPa, the synergistic effect predicted by the model reached its maximum, yielding a peak quantification value of 1.87 lg(CFU/mL). Conclusion This research quantitatively elucidates the augmented sterilization efficacy conferred by the SAEW-UHP parallel technology, utilized the smallest dosage and the lowest processing intensity to achieve the best bactericidal effect, which furnishing a theoretical underpinning for fresh produce storage strategies, offering novel approaches to green processing, and providing a guarantee for food microbial safety.

Objective To explore the browning prevention effects of radio frequency and heat shock treatment on honey peach during frozen storage. Methods Heat shock and radio frequency with different durations were used for pretreatment, and the changes in browning and quality were monitored over a 7 days frozen storage period. Results Compared with heat shock treatment, radio frequency treatment showed a smaller impact on the TSS/TA and pH of the peaches, and significantly reduced electrical conductivity (P<0.05), indicating that it could be better maintain the integrity of the peach cell membrane by radio frequency pretreatment. Based on the studies of key enzymes, substrates, and products related to browning, it showed a good inhibitory effect of radio frequency treatment on the activity of polyphenol oxidase, soluble quinones, and total phenols in frozen peaches, and which had a certain effect on maintaining catalase activity. This could reduce the degree of fruit browning and better resist the damage of reactive oxygen species to the peach fruit. A slight increase in malondialdehyde content was observed under higher temperature of radio frequency treatment, but there was no significant difference (P>0.05). Conclusion Radio frequency treatment has a good inhibitory effect on peach browning and can better maintain the physicochemical quality of the peaches.

In recent years, Actinidia industry has developed rapidly in China. The Actinidia plant area and production both rank the first all over the world. The standardization of Actinidia production are becoming higher. But it lacks competitiveness in quality and trade, can not meet the domestic and international market demand for high-quality Actinidia. Therefore, perfecting the quality and safety standard system of Actinidia in our country will be an important method to improve the market competitiveness. This article systematically sorts out China’s current Actinidia quality and safety standards, summarizes the quality and safety of each link of Actinidia before, during and after production, analyzes the current situation of China’s Actinidia quality standard system construction, as well as the main problems, and puts forward suggestions for the construction of the whole process of Actinidia quality and safety control system, in order to promote the high quality development of China’s Actinidia industry.

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.