To establish a method for simultaneous determination of 6 kinds of synthetic sweeteners in tea and tea products by QuEChERS-ultra performance liquid chromatography-tandem mass spectrometry.

Samples were extracted with acetonitrile-water (8:2, V:V), salted out with anhydrous magnesium sulfate and sodium acetate, and purified via dispersive solid-phase extraction using octadecylsilane adsorbent and N-propylethylenediamine adsorbent sorbents. Chromatographic separation was performed on a Waters ACQUITY UPLC HSS T3 column (100 mm×2.1 mm, 1.8 μm) using gradient elution with a water-acetonitrile mobile phase at a flow rate of 0.2 mL/min and an injection volume of 5 μL. The analytes were detected in electrospray negative-ion multiple reaction monitoring mode and quantified by external standard method.

The linear relationship of the 6 kinds of synthetic sweeteners was good within the mass concentration range of 2–1000 μg/kg (r>0.99). The limits of detection were 5–25 μg/kg and the limits of quantitation were 15–75 μg/kg. The average recoveries at 100, 500, 2500 μg/kg spiked levels ranged from 88.34%–103.21%, with relative standard deviations of 0.56%–7.63%.

The proposed method is simple,rapid, sensitive, accurate and reliable, making it well suited for the simultaneous rapid detection of various synthetic sweeteners in tea and tea products.

To optimize the extraction process for total flavonoids from pomelo flowers and investigate their antioxidant activity.

The extraction process of total flavonoids, the bioactive constituents from pomelo flower extracts, was optimized by single-factor experiments and orthogonal tests, while their antioxidant activities were evaluated.

The optimal extraction process conditions of total flavonoids from pomelo flowers were as follows:solid-liquid ratio 1:30 (g:mL), ethanol volume fraction 70% and ultrasonic time 50 min. Under these conditions, the extraction rate of total flavonoids was 12.44%. When the total flavonoid content was 49.86 mg/g, the scavenging rates of 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) disodium salt kation (ABTS⁺) and 1,1-diphenyl-2-picrylhydrazyl(DPPH) radicals reached 93.91% and 92.59%, respectively. The scavenging rate of hydroxyl radicals was as high as 99.51%, when the total flavonoid content was 24.93 mg/g.

Total flavonoids extracted from pomelo flowers exhibit excellent antioxidant capacity and possess superior application value in the food industry.

To comparatively study the Bact/Alert 3D microbiological detection system method(referred to as the instrument method) in the detection of commercial sterility items of ultra-high temperature instantaneous (UHT) sterilized milk, pure milk and room-temperature yogurt, with reference to the national standard methods.

The inclusivity of the instrument method was assessed by performing suitability tests on 36 kinds of microbial species. The sensitivity and detection time of the 2 methods were compared by detecting UHT pure milk artificially contaminated with Bacillus licheniformis and room-temperature yogurt artificially contaminated with Candida albicans using the GB 4789.26—2023 National food safety standard-Food microbiological examination-Commercial sterility testing (national standard method) and the instrument method; sensitivity was compared using 50% limit of detection (LOD₅₀), and the detection timeliness was evaluated. Additionally, the sensitivity was validated across 5 laboratories.

The instrument method demonstrated 100% inclusivity for the 36 kinds of microbial species tested. The LOD₅₀ of the instrument method was slightly lower than that of the national standard method for UHT pure milk with Bacillus licheniformis, but slightly higher for room-temperature yogurt with Candida albicans. The time to positivity for the instrument method was significantly shorter than that of the national standard method.

The instrument method shows good applicability for the 36 kinds of microbial species tested.While there are slight differences in sensitivity compared to the national standard method depending on the sample matrix, the instrument method offers superior timeliness.

To investigate the effects of different storage durations on the volatile flavor components of Osmanthus fragrans‑aged liqueur by gas chromatography‑tandem mass spectrometry (GC‑MS/MS).

Taking Chuanshanyan cave‑aged Osmanthus fragrans‑aged liqueur as the research object, 3 groups of samples were selected:initial bottling stage, after 2 years of storage durations and after 3 years of storage durations. GC‑MS/MSwas used to qualitatively detect and compare the volatile flavor components of the Osmanthus fragrans‑aged liqueur at different storage durations.

With increasing storage durations, the total number of volatile flavor compounds in the Osmanthus fragrans‑aged liqueur showed an initial increase followed by a decrease: 29 kinds of compounds were detected at the initial bottling stage, which increased to 32 kinds of after 2 years of storage durations, and further decreased to 27 kinds of after 3 years of storage durations. The number of alcohol species remained stable across all 3 stages, but their content gradually decreased with prolonged storage. The numbers of ester and aldehyde both exhibited an initial increase followed by a decline, with esters decreasing significantly after 3 years of storage, and acids increasing by one species at the 2‑year stage and then remaining stable. Other compounds gradually diminished during storage and completely disappeared after 3 years. During the aging process, unstable and pungent flavor components gradually diminished.

This study reveals the evolution patterns of volatile flavor compounds in Osmanthus fragrans‑aged liqueur during cave aging, clarifies the differential responses of various flavor components to the storage duration, and makes the aroma structure of structure more streamlined and coordinated. It can provide a reference for controlling reasonable storage durations and ensuring stable quality production of this type of characteristic fruit liqueur.

To investigate the flavor quality characteristics of sun-dried green tea from Mangjing Village, Jingmai Mountain.

Sun-dried green tea samples from different regions were selected as research objects. The quality components of tea samples were detected by biochemical component analysis, electronic nose technology and headspace solid-phase microextraction-gas chromatography-mass spectrometry, and the key aroma components were screened in combination with the relative odor activity value.

The biochemical components of sun-dried green tea from different regions showed certain differences, whereas the overall variation was relatively small. Electronic nose analysis indicated that all samples exhibited the highest response values on the W1S sensor. Although differences in volatile compounds were observed among samples, their overall odor profiles were highly similar. A total of 126 volatile compounds were identified by gas chromatography-mass spectrometry.Among them, linalool, hexanal, nonanal, octanal, heptanal, hexanol, α-ionone, α-terpineol and 1-octen-3-ol were identified as key aroma-active compounds in tea samples from different regions.

Under the same mountain ecological environment, regional differences exert relatively limited effects on the flavor characteristics of sun-dried green tea. This study provides a reference for revealing the regional flavor characteristics of sun-dried green tea from Mangjing Village, Jingmai Mountain.

To systematically evaluate the quality of Perilla frutescens seeds from diverse germplasm sources by integrating principal component analysis with the technique for order preference by similarity to ideal solution (TOPSIS) using a comprehensive multi-indicator framework, and to identify and screen for elite Perilla frutescens seed germplasm resources.

The total flavonoids, rosmarinic acid, thousand-seed weight, moisture content, oil content and relative content of fatty acids in the seeds of 31 purple Perilla frutescens germplasms were tested. Principal component analysis was used to screen the key indicators affecting the quality of purple Perilla frutescens seeds, and TOPSIS was employed for comprehensive quality evaluation. Systematic cluster analysis was used for resource classification.

The total flavonoids and rosmarinic acid contents of the 28th germplasm of purple Perilla frutescens seeds were significantly higher than those of other germplasms; the oil content of the 3th germplasm was the highest at 44.67%; the fatty acid test results indicated that the fatty acids in purple Perilla frutescens seeds were mainly composed of palmitic acid, stearic acid, oleic acid, linoleic acid and α-linolenic acid; the 4th germplasm resource had the highest α-linolenic acid content of 75.47%. Principal component analysis extracted 3 principal components with eigenvalues greater than 1. Based on the criterion that the absolute value of the loading value is greater than 0.4, the indicators with the largest loading values in different directions on each principal component were selected as the key indicators for comprehensive quality evaluation, and then the TOPSIS method was used for comprehensive evaluation. According to the relative proximity degree ranking, the 28th germplasm was the one with the highest comprehensive quality, possessing both high medicinal components and good oil quality. Systematic cluster analysis divided the 31 purple Perilla frutescens seeds into 4 categories: high medicinal component-high-quality oil use type, balanced medicinal and oil type, oil use specialized type and basic type.

This study established a multi-index comprehensive evaluation method for the quality of purple Perilla frutescens seeds, providing a theoretical basis for the development of purple Perilla frutescens functional oils and the selection of medicinal resources.

To explore the genomic characteristics and drug resistance of Salmonella Rissen in Yongchuan District, Chongqing from 2023 to 2025.

The 10 strains of foodborne Salmonella Rissen isolated in Yongchuan District, Chongqing City from 2023 to 2025 were identified, subjected to molecular identification, drug sensitivity tests and whole-genome sequencing. Based on sequencing data, molecular tracing and prediction of drug resistance genes were conducted.

The 10 strains of Salmonella Rissen had a resistance rate of 100.00% to tetracycline (TET), and the resistance rates to ampicillin (AMP), ampicillin/sulbactam (AMS), chloramphenicol (CHL),florfenicol (FFC) and trimethoprim/sulfamethoxazole (SXT) were greater than or equal to 50%, and all showed multi-drug resistance strains. All of the Salmonella Rissen carried a total of 94 drug resistance genes of 8 types. The prediction results of drug resistance genes were highly consistent with the drug resistance phenotype. A total of 9 virulence islands were carried. All isolates carried C63PI, SPI-1–3, SPI-5, SPI-8 and SPI-9 virulence islands.Phylogenetic analysis revealed that in this study, Salmonella Rissen was more closely related to the Eurasian branch, and there was clustering between the food strain and the case strain.

In Yongchuan District, the problem of drug resistance and multi-drug resistance of Salmonella Rissen in foodborne diseases is particularly prominent, the drug resistance phenotype is highly correlated with the genotype, and there is clustering between food isolates and human isolates. The quarantine of pathogenic bacteria and food hygiene education in the food trade and circulation links should be strengthened. Meanwhile, it is suggested to establish a whole-genome combined drug resistance analysis database of Salmonella in this region, strengthen gene monitoring and research on drug resistance mechanisms, achieve precise traceability of pathogenic bacteria, realize networked monitoring of pathogenic bacteria, thereby optimizing drug resistance prevention and control in the region, guiding clinical medication, and providing a scientific basis for achieving the health of the entire population.

To investigate the dynamic changes of metabolites in Betula pendula Roth juice during the harvesting period, and analyze their intrinsic associations with physicochemical indices including soluble solid content,pH and electrical conductivity.

Betula pendula Roth juice collected on 7 consecutive days from the Yakeshi production region in Inner Mongolia, China, was pretreated by methanol-water (7:3, V:V) ultrasonic extraction in an ice-water bath, centrifugation and 0.22 μm membrane filtration, and was then analyzed by ultra performance liquid chromatography-quadrupole-orbitrap high resolution mass spectrometry (UPLC-Q-Exactive-MS) based untargeted metabolomics. Principal component analysis (PCA) was used to examine the overall variation of the metabolome,differential metabolites were screened with variable importance in projection (VIP)>1 and P<0.05, key metabolic pathways were resolved by UpSet plots, volcano plots and Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment analysis, and the soluble solid content, pH and electrical conductivity were determined to construct a metabolite-physicochemical index correlation network by Spearman rank correlation analysis.

The results showed that the metabolome of Betula pendula Roth juice could be divided into 3 stages along the harvesting period:D1–D3, stress-responsive metabolites such as alkaloids and organic acids were up-regulated, with log₂FC of +0.88 for pilocarpine and +2.68 for alpha-ketoglutaric acid, and as many as 119 kinds of differential metabolites (41 kinds of them unique to this comparison) were detected between D1 and D2; D4–D6, carbohydrates, lipids and amino acids predominated, the pentose phosphate pathway, starch and sucrose metabolism and phenylpropanoid biosynthesis were significantly enriched and alpha-linolenic acid (log₂FC=+4.21) and methyl jasmonate (log₂FC=+2.95) peaked at this stage; D7, most functional metabolites were down-regulated whereas aroma-associated benzenoids increased selectively,and only 4 kinds of differential metabolites were detected between D6 and D7, indicating that the metabolome tended to be stable. During the harvesting period, the pH, electrical conductivity and soluble solid content of Betula pendula Roth juice ranged from 4.11 to 6.99, from 211.16 to 608.40 μS/cm and from 0.80 to 2.66 °Brix, respectively; the correlation network showed that the soluble solid content was strongly and positively correlated with various carbohydrates and organic acids, and DL-malic acid and acetic acid acted as metabolic hub compounds simultaneously linking multiple physicochemical indices.

The metabolite composition of Betula pendula Roth juice undergoes a clearly stage-dependent evolution within a harvesting period of only 7 d, D4–D6 represent the stage richest in functional metabolites, and DL-malic acid and acetic acid can serve as candidate markers for quality evaluation; these findings provide a theoretical basis for scientifically defining the harvesting window and for the quality evaluation and high-value utilization of Betula pendula Roth juice.