Objective To predict and control the fermentation process of Agrobacterium sp. A02 strain to produce curdlan, establish a time-varying model to simulate bacterial growth and obtain the kinetic changes of curdlan production and sucrose consumption. Methods The viable bacteria count, sucrose content and curdlan content during the batch fermentation process of Agrobacterium sp. A02 were measured, and the experimental values were fitted using Logistic equation, Luedeking-Piret equation and Luedeking-Piret-Like equation, respectively. Results The fitting results indicated that the 3 kinds of models were applicable to the growth kinetics of bacterial cells, the generation kinetics of pectin, and the consumption kinetics of sucrose. The R² were above 0.99, and the significance level was extremely significant. The errors between the fitted and experimental values were less than 10%, indicating a good fit. Conclusion The established bacterial growth kinetics model, sucrose consumption kinetics model and curdlan production kinetics model can predict and describe the dynamic metabolic changes of Agrobacterium sp. A02 during the fermentation process, providing theoretical support for describing the fermentation kinetics characteristics and industrial production of curdlan.

Objective To explore the effects of glnA gene on the production of curdlan by Agrobacterium. Methods A glnA gene knockout strain ΔglnA was constructed in this paper. The growth and metabolism of ΔglnA strain and the changes in yield, gel properties and infrared structure of the obtained gum were analyzed, and the expression of genes related to the synthesis of curdlan was explored by quantitative real-time polymerase chain reaction. Results The amino nitrogen consumption of the ΔglnA strain during fermentation was consistent with that of CGMCC11546. In terms of sucrose consumption, there was no significant difference before 12 h, but there was a significant difference between the ΔglnA strain and CGMCC11546 after 15 h, and sucrose consumption was significantly reduced compared to CGMCC11546. The ΔglnA strain could produce approximately 4 g/L of natural gum, which was 60% lower than CGMCC11546. Conclusion The glnA gene does not affect bacterial growth or the structure of collagen, but it can reduce the synthesis of collagen. This study provides insights into the role of glnA in curdlan production and lays a molecular biological foundation for further efforts to enhance curdlan yield.

Objective To analyze the status of foodborne pathogenic bacteria contamination in meat and meat products in Yantai City, Shandong Province from 2020 to 2023, and understand the safety of related food in the city. Methods According to national food safety standard Food microbiological examination GB 4789 series standards and the requirements of Shandong food pollutants and harmful factors risk monitoring manual, 6 kinds of foodborne pathogens were detected from meat and meat products, including Salmonella, Listeria monocytogenes, Yersinia enterocolitica, Campylobacter, Diarrheagenic Escherichia coli and Staphylococcus aureus. Results The 5 kinds of foodborne pathogens and 46 positive strains were detected in 363 samples, with the total detection rate of 12.67%. The highest detection rate was Salmonella (10.48%), followed by Campylobacter (1.97%) and Staphylococcus aureus (1.33%), and no Diarrheagenic Escherichia coli was detected. Among the 4 types of samples, the highest detection rate was in raw poultry meat (26.67%) and the lowest was in cooked meat products (2.35%). The detection rate of Salmonella in prepared meat products reached 20.00%. The detection rates of pathogenic bacteria in the samples collected by farmers’ markets and online stores were relatively high (19.53%, 22.22%). Salmonella had the highest probability of causing illness in the third quarter. Conclusion Meat and meat products in Yantai City are contaminated by foodborne pathogens to various degrees, so it is necessary to focus on raw poultry meat and bulk prepared meat products, especially those originating from farmers’ markets and online stores, and it is important to strengthen the relevant circulation supervision, enhance food safety awareness and take measures to reduce the risk of cross-contamination during the sale of bulk meat products, so as to ensure food safety for consumers.

Objective To investigate and analyze the contamination of polycyclic aromatic hydrocarbon (PAHs) in 4 kinds of medicinal and edible substances, Aucklandiae radix, Citrus reticulatae pericarpium, Polygonati rhizoma, Fritillaria cirrhose bulbus in Chongqing, and assess human exposure risk from PAHs residues through ingestion of 4 kinds of substances. Methods A total of 160 samples were collected from 10 districts/counties in Chongqing. The residues of 16 kinds of PAHs were determined using gas chromatography-mass spectrometry. The contamination levels were evaluated based on the maximum residue limits of benzo[a]pyrene and PAH4 (sum of benzo[a]anthracene, chrysene, benzo[b]fluoranthene, and benzo[a]pyrene) set by the European Commission for “food supplements containing botanicals and their preparations” and “dried herbs”. The pollution characteristics of PAHs in the 4 kinds of substances were analyzed, and the sources were identified using isomer ratio analysis. Health risk assessment was conducted using the increased lifetime cancer risk (ILCR) model recommended by the US Environmental Protection Agency (USEPA). Results PAHs were detected in all Aucklandiae radix, Citrus reticulatae pericarpium, Polygonati rhizoma, Fritillaria cirrhose bulbus. The detection rate of the highly carcinogenic benzo[a]pyrene was 24%, with an exceedance rate of 1.25%, while the exceedance rate for PAH4 was 1.9%. Citrus reticulata peel exhibited the highest benzo[a]pyrene detection rate (83%), and its maximum PAH4 content reached 151.66 μg/kg, exceeding the MRL by more than threefold. PAHs in all 4 kinds of substances were predominantly low-molecular-weight 2-3 ring compounds. The ILCR values of cancer risk caused by taking 4 kinds of substances in different populations were 1.46×10^-7-7.26×10^-7, 1.21×10^-6-6.04×10^-6, 1.89×10^-7-9.38×10^-7, 6.96×10^-8-3.46×10^-7, respectively. Conclusion The 4 kinds of dual-purpose substances are contaminated with PAHs at varying levels, primarily due to biomass or coal combustion. The health risks from oral intake of Aucklandiae radix, Polygonati rhizoma, Fritillaria cirrhose bulbu are low and within acceptable limits. However, Citrus reticulatae pericarpium poses a potential health risk due to PAHs exposure, warranting further attention.

Germinated brown rice, as a functional food ingredient, is widely used in food processing. Germinated brown rice is rich in nutrients, including γ-aminobutyric acid, γ-glutamine, dietary fiber, polysaccharides, glutathione, inositol, and octacosanol, among other bioactive substances. Germinated brown rice has a variety of physiological effects, such as anti-oxidation, lowering blood lipids, lowering blood pressure, preventing diabetes, preventing and treating cancer; it also has physiological functions such as improving memory, preventing senile dementia, sobering up, regulating emotions, improving skin, and enhancing gut microbiota. The staple food products processed with germinated brown rice as raw materials include Mantou, rice, noodles, bread, biscuits, etc. They can also be processed into germinated brown rice tea, fermented drinks, brown rice wine and other drinks; it can also be processed into germinated brown rice noodles, brown rice porridge, brown rice cake, brown rice vinegar and other foods. By improving the production technology of germinated brown rice, developing distinctive germinated brown rice food, the industrialization process can be accelerated. This article reviewed the nutritional characteristics, bioactive substances, physiological functions, and application research progress of germinated brown rice in the food industry, in order to provide reference for the promotion and application of germinated brown rice.

Objective To establish a rapid analysis method based on solid phase extraction-high performance liquid chromatography-evaporative light scattering detection (SPE-HPLC-ELSD) for determining the γ-aminobutyric acid (GABA) content in edible enzymes from medicinal and edible homologous sources. Methods Fermented panacis quinquefolii radix liquid was selected as a representative sample. After centrifugation (8000 r/min, 10 min) and ultrasonic extraction (10 min, 25 ℃), 3 kinds of different sample pretreatment methods—non-purification, dispersive solid phase extraction purification, and hydrophilic-lipophilic balance (HLB)-based solid phase extraction purification were compared and optimized. An optimized HPLC-ELSD instrumental method was developed to achieve accurate content determination. The method was then applied to determine the GABA content in other medicinal and edible homologous enzyme products. Results GABA was determined by optimized SPE-HPLC-ELSD. GABA showed a good linear relationship (r=0.999) in the mass concentration range of 50-2000 μg/mL. The recovery rate ranged from 85.93% to 96.30%, with a repeatability relative standard deviation of 0.87% (n=6). Conclusion This method is efficient and accurate, suitable for the quantitative analysis of GABA in various medicinal and edible homologous enzymes. It also provides a new approach and reference for GABA determination in complex matrices and for detecting small molecules with strong polarity and low ultraviolet absorption.

Objective To investigate the potential of Cornus officinalis extract (COE) to repair skin damage caused by ultraviolet-B (UVB) exposure and to elucidate the underlying mechanisms involved. Methods By detecting the expression of UVB induced matrix metalloproteinases (MMPs) and pro-inflammatory cytokines in human keratinocytes cells (HaCaT), the photoprotective effect of COE was evaluated, and its antioxidant enzyme activity and collagen content were assessed. After exposure of mouse hairless skin to UVB radiation, extracts were applied topically and epidermal thickness, skin water content and collagen mRNA expression were determined. Results Under UVB irradiation (354.128 mJ/cm²), 1 mg/mL COE significantly enhanced antioxidant enzyme activity and significantly reduced the expression of pro-inflammatory cytokines prostaglandin E2, interleukin-1 α, and interleukin-6; simultaneously reduced the expression of MMPs; the collagen content significantly increased, with the expression levels of type I collagen and type III collagen proteins increasing by 13% and 75%, respectively. In addition, COE could alleviate the thickening of mouse skin epidermis and loss of collagen caused by UVB radiation. Meanwhile, COE treatment reduced the content of malondialdehyde (MDA) by 69%, and increased the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) by 27% and 234%, respectively. Analysis of mRNA expression in mouse epidermis showed that treatment with COE resulted in a decrease in mRNA expression levels of Mmp1a and Mmp3, while mRNA levels of Col1a1 and Col3a1 increased. Conclusion COE can improve skin damage caused by UVB radiation. This improvement was associated with increased activity of antioxidant enzymes in cells, as well as reduced expression of pro-inflammatory cytokines and MMPs. The aim of this study is to further investigate the photoprotective potential of Cornus officinalis against UVB induced skin damage through mouse and cell models, and elucidate its potential mechanisms, providing a theoretical basis for the treatment of skin diseases caused by UVB photoaging and the development of new drugs from Cornus officinalis.

Objective To establish a method for determining the volatile components of lubricating oil mixed in edible oil by headspace-gas chromatography-mass spectrometry. Methods The 1.0 g oil sample was directly taken into a 10 mL headspace bottle, then capped and sealed. Headspace-gas chromatography-mass spectrometry analysis was carried out at 90 ℃ equilibration for 20 min. Qualitative analysis was performed on 5 kinds of compounds: 4-methyl-2-pentanol, isooctanol, nonane, undecane and dodecane, while quantitative analysis was performed on isooctanol, nonane, undecane, and dodecane. Results The 4 kinds of quantitative compounds showed good linear relationships within the range of 0.5-8.0 mg/kg, and the correlation coefficients were all above 0.9980. Soybean oil was used as the sample for the spike recovery experiment. The recoveries of nonane, isooctanol, undecane, dodecane were 91.5%-98.2%, 81.9%-92.7%, 92.8%-94.6%, 89.3%-93.7% respectively and the relative standard deviations were all less than 10%. In the 5 kinds of edible oils: Soybean oil, peanut oil, rapeseed oil, corn oil and sunflower seed oil, the limits of detection of nonane, isooctanol, undecane, dodecane were 0.006-0.013 mg/kg, 0.016-0.045 mg/kg, 0.011-0.020 mg/kg, 0.020-0.036 mg/kg respectively. Conclusion This method has the advantages of simple operation and rapid detection, and does not have high requirements for the instrument, which can be carried out in general laboratories, and is suitable for the screening of trace lubricating oil contamination in edible oil.

Objective To prepare sodium alginate-egg gel beads using sodium alginate and egg as carriers through calcium lactate complexation, optimize their preparation process, and conduct texture analysis. Methods The sodium alginate-egg gel beads were prepared using the cross-linking method, and based on single-factor experimental design, the effects of calcium lactate concentration, curing time, and curing temperature on the hardness of the gel beads were explored. Results Under single-factor conditions, the preparation process of the gel beads was optimized using response surface methodology. The optimal preparation conditions were: 6% calcium lactate concentration, 27 minutes of curing time, and a curing temperature of 39 ℃. Under these conditions, the prepared gel beads had the following properties: Cohesiveness of 0.6457, recovery of 0.6627, hardness of 9.9983 gf, elasticity of 1.0000, chewiness of 3.5975 gf, and water content of 84.56%. Conclusion This study prepares alginate-egg gel beads with good recovery and elasticity, and determines the optimal process for the preparation of the product. This provides theoretical support and reference for expanding the application prospects of sodium alginate-egg gel beads in the fields of biomedicine and material science.

Objective To explore the effects of different drying methods on the physicochemical characteristics and volatile aroma components of Amomum tsaoko. Methods The fresh fruit of Amomum tsaoko in Nujiang Prefecture was used as the raw material, and 6 kinds of drying methods commonly used in Nujiang Prefecture were used to dry it. The physical and chemical indexes such as color and volatile oil content of Amomum tsaoko were detected, and the volatile aroma components were analyzed by gas chromatography-mass spectrometry (GC-MS). Results The color difference and volatile oil content of Amomum tsaoko dried by different drying methods were significantly different. The L^*, a^* and b^* of Amomum tsaoko dried by air energy heat pump drying and high efficiency electric energy drying were higher, suggesting that the color of Amomum tsaoko was bright brown red and the quality was high. The volatile oil content was (1.04±0.07)-(1.29±0.07) mL/100 g. The volatile oil content of natural sun drying, air energy heat pump drying and high efficiency electric energy drying was relatively high. The composition of volatile aroma substances in Amomum tsaoko dried by different drying methods had both similarities and differences. There were 19 kinds of common substances, and the relative content of most common substances was significantly different. There were 13 kinds of main volatile aroma components (relative content≥3%), and the common components were eucalyptol, trans-nerolidol, P-propylbenzaldehyde and (Z) -citral, and their relative contents had great difference. The relative content of aldehydes and alcohols in the volatile aroma components of Amomum tsaoko was 82.75%-95.69%. The relative content of aldehydes in Amomum tsaoko obtained by biomass hot air drying was the highest, and the alcohols in other drying methods were the highest. Conclusion Therefore, different drying methods have great influence on the physical and chemical characteristics and aroma of Amomum tsaoko. The color of Amomum tsaoko is different, and the aroma and flavor of Amomum tsaoko are significantly different.