Objective To investigate the effects of low-temperature fermentation processes and fermentation duration on the aroma composition and aromatic characteristics of summer-harvested Jingshan black tea. Methods First, headspace solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) combined with sensory evaluation was used to analyze the aroma components of 12 samples fermented at 3 temperatures (25, 28 and 35 ℃) and four durations (2.5, 4.0, 5.5 and 7.0 h). Second, principal component analysis (PCA) and hierarchical cluster analysis (HCA) were employed to explore the differences among samples under varying fermentation conditions (temperature and duration). Finally, Orthogonal partial least squares-discriminant analysis (OPLS-DA) with variable importance projection (VIP) scores and relative odorant activity value (OAV) was conducted to screen differential volatile compounds related to fermentation conditions. Results A total of 86 kinds of aroma components were analyzed and identified by the above-mentioned methods. Among them, 15 kinds of substances, such as dimethyl sulfide, linalool, (E,E)-2,4-heptadienal, indole and geraniol, were identified as the key differential volatile compounds under different fermentation conditions (temperature and time). Compared with other fermentation time samples, 4.0 h samples had higher concentration of volatile compounds and better quality. Among the samples with a 4.0 h fermentation duration, the samples fermented at 25 ℃ and 28 ℃ obtained higher sensory scores and presented distinct aroma profiles. At this duration, 25 ℃ and 4.0 h-fermented samples displayed floral aromas dominated by dimethyl sulfide, dehydro-linalool, linalool and neral, while 28 ℃ and 4.0 h-fermented samples exhibited fruity notes characterized by myrcene, citral and geraniol. Conclusion Low-temperature fermentation processes and fermentation duration critically influence the aromatic quality of Jingshan black tea.

Objective To understand the metal element contamination in liquid milk in Inner Mongolia region from 2022 to 2023 and assess the metal health exposure risk for the population in Inner Mongolia region. Methods A total of 4103 samples of locally produced liquid milk were collected from Inner Mongolia region. Lead, total mercury, cadmium, chromium and total arsenic were detected using inductively coupled plasma mass spectrometry. The inverno comprehensive pollution index method was used to evaluate the pollution levels of these elements. Considering the actual dietary intake of residents in Inner Mongolia region, the carcinogenic risk assessment (TCR) and non-carcinogenic risk assessment [target hazard quotient (THQ)] were employed to assess the health risks posed by metal elements in liquid milk to the population in Inner Mongolia region. Results In the 4013 samples monitored, all 5 kinds of metal elements were detected. The over-limit detection rate for lead was 22.26% (187/840), for cadmium it was 5.83% (49/840), for total mercury it was 5.12% (43/840), for total arsenic it was 6.54% (55/841), and for chromium it was 40.18% (262/652). Lead, total mercury, and total arsenic all had samples exceeding the limits, with exceedance rates of 5.83% (49/840), 0.119% (1/841), and 0.12% (1/841), respectively. The inverno index for all 5 kinds of metal elements was below 0.7; the TCR for total arsenic and cadmium was less than 10^-4, Within an acceptable risk range; THQ of lead, chromium, and total mercury were all less than 1. Conclusion This study systematically analyzed and comprehensively assessed the sources of heavy metal pollution in liquid milk from different production and processing types, providing a scientific basis for government decision-making, regulation, and the revision of national food safety standards.

Objective To evaluate the quality differences among the main Vitis vinifera L. varieties in Shanghai, identify key quality indicators. Methods A total of 34 batches of Vitis vinifera L. samples were collected from 10 major cultivars cultivated by 7 enterprises in Shanghai. Twelve quality parameters, including cluster weight, berry weight, fructose, glucose, total acid, vitamin C, amino acids, and anthocyanins, were analyzed to assess Vitis vinifera L. quality from 3 perspectives: Physical appearance, intrinsic nutritional quality and overall quality. Results There were significant differences (P<0.05) in the physical appearance, intrinsic nutritional quality and overall quality of Vitis vinifera L. varieties. Shine Muscat performed exceptionally well in sugar-acid balance, Zuijinxiang showed high levels of vitamin C and overall nutritional quality, Jumeigui had a notable advantage in fructose and glucose content, and Shenyuan exhibited the highest total amino acids, though the amino acid composition needs optimization. Principal component analysis revealed that the main factors contributing to quality differences were the sugar-acid ratio, amino acid composition and fruit weight. Conclusion The major Vitis vinifera L. cultivars in Shanghai exhibit distinct quality advantages. Shine Muscat, Zuijinxiang and Jumeigui are particularly suitable for promotion as premium table Vitis vinifera L. varieties. These findings provide a scientific basis for Vitis vinifera L. varieties breeding, cultivation management, and market positioning, while also serving as a reference for consumer health and the development of functional foods.

Objective To establish a visual detection method of Salmonella based on recombinant enzyme polymerase amplification-CRISPR/Cas12a. Methods In this study, recombinase polymerase amplification (PRA) was combined with clustered regularly interspaced short palindromic repeats/associated protein 12a (CRISPR/Cas12a) system. RPA primers and CRISPR-derived RNA (crRNA) were designed and synthesized based on the target invA gene of Salmonella. Fluorescence and test strip methods were employed to read the results. The optimized RPA-CRISPR/Cas12 detection system were evaluated for specificity and sensitivity, and was applied to the detection of food samples. Results Nano gold test strip base on nucleic acid were developed. The established RPA-CRISPR/Cas12 detection method could specifically detecting Salmonella with a sensitivity of 80 CFU/mL within 1.5 h. Used this method to detect 21 kinds of food samples, the results from fluorescence and test strip read were consistent, with a Salmonella detection rate of 4.8%, which was completely consistent with the results of the national standard method. Conclusion The Salmonella RPA-CRISPR/Cas12a visual detection method established in this study has high specificity and sensitivity and is valuable for on-site rapid detection of Salmonella.

Objective To evaluate the heavy metal contamination characteristics and health risks of Ziziphus jujuba Mill. from 3 major production regions (Jiao cheng Jun Ziziphus jujuba Mill., Tai gu Hu ping Ziziphus jujuba Mill., and Xiang fen Guan tan Ziziphus jujuba Mill.) in Shanxi Province. Methods Sample pretreatment was performed using a microwave digestion system, followed by quantitative analysis of Cr, Ni, Pb, Cd, As, and Hg in 180 Ziziphus jujuba Mill. samples via inductively coupled inductively coupled plasma-mass spectrometry (ICP-MS). Experimental data were standardized using Microsoft Excel 2022, and non-parametric statistical analyses (Kruskal-Wallis H test, Spearman’s rank correlation) were conducted with SPSS 26.0 IBM to investigate elemental distribution patterns and regional correlations. Health risks were assessed using the United States Environmental Protection Agency (USEPA) model with exposure parameters. Results A highly sensitive multi-element simultaneous detection method was established with a limit of detection of 0.003 to 0.010 mg/kg, with a recovery rates of 92% to 108% and a precision of 2.9% to 4.5%. Key findings included: (1) Hg was undetected in all regions, while Cr and Ni were universally detected, Pb detection rates exhibited regional differences, with the highest in Xiangfen, Cd detection rates were notably higher in the Taigu; (2) The studied elements exhibited significant spatial heterogeneity; (3) Pb, Ni and Cr in Jiao cheng Jun Ziziphus jujuba Mill. and Xiang fen Guan tan Ziziphus jujuba Mill. exhibited a highly significant positive correlation, while the correlations of the same elements between Tai gu Hu ping Ziziphus jujuba Mill. and Xiang fen Guan tan Ziziphus jujuba Mill. showed a synchronous enhancement; (4) health risk assessment identified potential non-carcinogenic risks for Cr and Pb in Xiangfen, and the daily intake of As approached but remained below the international threshold. Conclusion This study systematically map the heavy metal contamination profile of Shanxi Ziziphus jujuba Mill. for the first time and propose region-specific grading standards for pollutants, providing a scientific basis for improving the quality and safety regulatory framework of jujube products.

With the rapid development of the Chinese economy, coffee consumption in China has rapidly expanded, and the processing scale of coffee and related products in China has grown significantly in recent years. However, many food safety risks caused by non-standard processing in the industry have also been exposed as the industry grows. Among them, risks such as excessive use of food additives beyond the scope, excessive mold contamination caused by poor initial processing hygiene conditions, and extreme emphasis on flavor and neglect of acrylamide contamination in baking are more prominent. These risks will be amplified with the surge in consumption. Therefore, it is urgent to introduce normative documents to effectively guide the industry to control non-standard work. At present, China has not yet issued national standards or other authoritative documents on risk control measures for coffee processing exposure, which is significantly different from international standards. This article focused on the main food safety risks currently present in the coffee processing industry, and provided some perspectives and suggestions for future regulatory documents on coffee processing. The significance of this article is to standardize the processing of the coffee industry, ensure effective supervision, strictly control illegal additives, and suppress fraudulent behavior, providing standard support for improving the rate of high-quality coffee.

Objective To develop an enzyme-linked immunochromatographic test strip for the determination of amanita toxin in mushroom based on immunochromatography. Methods N-hydroxysuccinimide (NHS) and N-(3-dimethylaminopropyl)-N’-ethylcarbodiimide hydrochloride (EDC) were used as activators, 6-aminohexanoic acid was introduced to obtain amanitin peptide hapten, and further conjugated with keyhole limpet hemocyanin (KLH) and bovine serum albumin (BSA) to prepare immunogen and coating antigen. Then, the immunogen was used to immunize Balb/c mice to prepare monoclonal antibodies. The colloidal gold immunochromatographic test strip for amanitin was successfully developed by preparing colloidal gold and gold labeled antibody, optimizing the concentration of coating antigen, secondary antibody and extracting solution, and then its cross reactivity, stability, repeatability, and accuracy were evaluated. Results The limits of detection of α-amatoxin, β-amatoxin, and γ-amatoxin peptide were 100, 20 and 50 μg/kg, respectively. The sensitivity was 100%, the false positive rate and false negative rate were 0%, and the results were consistent with the existing instrumental methods without cross reaction with other mushroom toxins. Conclusion The test strip has the characteristics of simple operation, high repeatability and good stability, and is suitable for on-sites creening and rapid detection of amanitin in mushrooms.

Objective To conducte compression tests and finite element mechanical simulations on Eriobotrya japonica (Thunb.) Lindl., and investigate its compression characteristics. Methods The compression deformation process of Eriobotrya japonica (Thunb.) Lindl. was repeatedly tested by universal electronic material testing machine, and the relationship curve between compression force and deformation was obtained. The feature points and feature chains of fruits pictures were extracted by image processing, and the 3D digital model of fruits was constructed. The stress and strain distribution of its fruits under compression was analyzed based on ANSYS Workbench 2024 R1 finite element simulation software. Results The yield load of Eriobotrya japonica (Thunb.) Lindl. fruit was 38.25 N. The average relative error between the finite element simulation model and compression test was 5.93%, which proved that the compression test of its fruit was reasonable and effective. The stress-strain cloud map of fruit compression test was obtained. It was found that the maximum stress position of Eriobotrya japonica (Thunb.) Lindl. was at the edge of the contact between the fruit and the upper pressure plate, the maximum stress value was 0.14057 MPa and the maximum strain value was 0.52233 mm. Conclusion In the process of picking and circulation of Eriobotrya japonica (Thunb.) Lindl., it shall be noted that the extrusion pressure generated by mechanical picking and fruit stacking shall not exceed 38.25 N to avoid mechanical compression damage. At the same time, it is necessary to do a good job of packaging buffering to protect the maximum stress part of its fruits.

Objective To screen lactic acid bacteria strains with strong ethanol stress resistance and investigate the effects of their biofilms under different ethanol concentrations and environmental disturbances. Methods The growth, biofilm formation, morphological changes and hydrophobicity of various lactic acid bacteria under ethanol stress were examined. The effects of different metal ions and D-galactose on the growth and biofilm formation of lactic acid bacteria were also explored. Results After 48 h of fermentation under 10% ethanol stress, the biomass and biofilm amount of Lacticaseibacillus paracasei were 1.16 and 0.12, respectively. After 24 h of fermentation, its hydrophobicity reached 42.80%, significantly higher than that of Lactiplantibacillus plantarum, Lacticaseibacillus casei, and Limosilactobacillus fermentum, indicating better ethanol stress resistance. Scanning electron microscopy showed that the thickness of the biofilm decreased significantly with increasing ethanol concentration. The addition of D-galactose and metal ions (Ca²⁺, Na⁺) significantly inhibited biofilm formation. Conclusion Lactic acid bacteria resist ethanol stress through biofilm formation, with ethanol stress resistance correlating closely to biofilm production. D-galactose and metal ions affect the growth and biofilm formation of lactic acid bacteria. This study reveals the relationship between ethanol stress resistance and biofilm formation in lactic acid bacteria, provides a theoretical basis and data support for developing lactic acid bacteria biopreparations suitable for high-ethanol food fermentation environments.

Objective To systematically analyze the nutrition, taste and texture characteristics of salt field shrimp, an ecological shrimp (Penaeus vannamei) that grows in salt field evaporation ponds or muddy and sandy water surfaces with a salinity of over 30‰. Methods Taking freshwater cultured Penaeus vannamei (D0) as control, the conventional nutritional components, amino acids, fatty acids, major mineral elements, active substances, free amino acids, nucleotides, quaternary ammonium compounds, organic acids, texture, and color after cooking of two kinds of salt field shrimps cultured in different salinity fields (Penaeus vannamei, recorded as Y45 and Y30 separately) in Binzhou City were analyzed, and their nutritional quality was evaluated. Results Compared with freshwater shrimp, salt field shrimp had higher protein and ash content, and lower fat content. The 18 kinds of amino acids were detected in both salt field shrimp and freshwater shrimp, with glutamic acid being found the highest level, followed by aspartic acid, and tryptophan the lowest content. The proportion of essential amino acids to the total amino acid content in shrimp of all 3 groups were higher than 35.38%, and the essential amino acid index was much higher than 100, indicating balanced amino acids and high nutritional value. The unsaturation degree of fatty acids in all three groups of shrimp was high and the mineral elements such as calcium, sodium, chlorine, and magnesium in salt field shrimp were significantly higher than those in freshwater shrimp. The content of active substances such as taurine and astaxanthin was much higher than that in freshwater shrimp, but their body color tended to be lighter after cooking. The nutritional quality index of protein, phosphorus, sodium, chlorine, and magnesium in salt field shrimp was much higher than 1, indicating that salt field shrimp had greater ability to provide these nutrients than to provide thermal energy. In terms of flavor substances, the content of free amino acids in salt field shrimp was as high as 3119.88 mg/100 g (Y45), and the content of Na⁺, Cl^-, betaine, and tartaric acid was significantly higher than that in freshwater shrimp. Free amino acids Arg, Gly, Ala, Glu, inorganic ions, betaine, tartaric acid, lactic acid, and succinic acid were the main contributors to its taste, while other organic acids, flavor nucleotides, reducing sugars, etc. also provided it with richer taste. From the texture results, it could be seen that the muscle hardness and shear force of salt field shrimp were low and the elasticity was high, which means the meat of salt field shrimp was more tender than that of freshwater shrimp. Conclusion In summary, salt field shrimp (Penaeus vannameii) is a food with high protein, low fat, balanced amino acid composition, fresh and sweet taste, and high dietary nutritional value.