To analyze the effects of drying methods and raw material cultivars on the metabolite profile of Guangxi oil tea, and identify key differential markers.

Untargeted metabolomics technology coupled with multivariate statistical methods was employed to systematically investigate the effects of 4 kinds of processing techniques, including freeze vacuum drying, microwave vacuum drying, microwave drying and aroma-enhancing machine drying, as well as 2 kinds of raw material cultivars (Gongcheng and Longsheng group species) on the secondary metabolite profiles of Guangxi oil tea.

Freeze vacuum drying significantly enriched lipids, phenolic and carbohydrate compounds, whereas microwave vacuum drying significantly increased the content of organic acids and amino acid metabolites. Furthermore, samples produced from the Gongcheng green tea exhibited superior flavor and nutritional quality, with their content of phenolic compounds, organic acids and terpenoids being significantly higher than that from the Longsheng green tea. Sensory evaluation results corroborated the regulatory role of small-molecule metabolites on the flavor quality of oil tea, and the treatment group using Gongcheng green tea combined with freeze vacuum drying achieved the highest overall sensory score of 94.63 among all groups. Subsequently, Pearson correlation analysis identified 18 kinds of marker metabolites significantly positively correlated with flavor attributes, which could serve as important quality control indicators for oil tea.

This study clarifies the significant advantages of the freeze vacuum drying technique and the Gongcheng green tea raw material in enhancing oil tea quality, which can provide key scientific evidence for establishing standardized processing techniques, selecting high-quality raw materials and implementing quality control within the Guangxi oil tea industry.

To investigate the effects of different drying methods on Millettia speciosa Champ.quality.

Millettia speciosa Champ. samples were processed into powder using vacuum microwave drying(VMD), vacuum drying (VD) and hot-air drying (HAD). Their microstructures were observed, and color difference, total flavonoids, total phenolics, polysaccharides and starch content were measured. Additionally, their ability to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulfonate acid) diammonium salt (ABTS) positive ion free radicals was assessed.

The VMD group exhibited the highest levels of total flavonoids (1.95±0.01) mg/g, total phenols (18.14±0.18) mg/g and polysaccharides (280.73±1.35) mg/g. The radical scavenging rate of DPPH (54.17±0.09)% and the positive ion radical scavenging rate of ABTS(37.37±0.00)% were both the best. VD yielded the second-highest values, while HAD produced the lowest, with significant differences among all 3 groups (P<0.05).

VMD optimally preserves Millettia speciosa Champ. components, including total flavonoids, total phenolics and polysaccharides, while enhancing radical scavenging capacity, making it the most suitable drying method.

To investigate the protective effects of Camellia nitidissima leaves extract on alcoholic liver injury in mice.

The 60 male Kunming mice were randomly divided into control group, model group, low-dose group (0.75 g crude drug /kg), medium-dose group (1.50 g crude drug /kg) and high-dose group (3.00 g crude drug /kg) (n=12 per group). The control and model groups were administered pure water by gavage, while extract groups received different doses of extract (20 mL/kg). After 5 hours, 40% elthanol (10 mL/kg) was administered to all groups except the control group for 14 consecutive days. After fasting for 16 hours following the last administration, 20 mL/kg ethanol was administered. Serum biochemical indicators, liver homogenate antioxidant markers (superoxide dismutase, glutathione, malondialdehyde, protein carbonyl) and inflammatory cytokines(interleukin-1β, interleukin-6 and tumor necrosis factor-α) were analyzed. The pathological changes of liver in mice were observed by hematoxylin-eosin (HE) staining.

Compared with the model group, the serum triglyceride, alanine aminotransferase, aspartate aminotransferase and tumor necrosis factor-α levels in the high dose group decreased by 21.76%, 15.88%, 12.23% and 37.17%, respectively. The content of superoxide dismutase in the liver of the high dose group increased by 14.96%, and the content of malondialdehyde decreased by 17.41%. The content of glutathione in the middle and high dose groups increased by 18.32% and 24.10%, respectively. The protein carbonyl content in the middle and high dose groups decreased by 15.38% and 19.33%, respectively. The serum interleukin-1β in the middle and high dose groups decreased by 43.27% and 49.72%, respectively. The interleukin-6 content in the low, middle and high dose groups decreased by 25.06%, 28.30% and 32.59%, respectively (P<0.05). HE staining showed that hepatocyte edema and ballooning were improved in the medium and high dose groups.

Camellia nitidissima leaves extract has a good protective effect on alcoholic liver injury in mice, which may be related to antioxidant and anti-inflammatory mechanisms. This study provides experimental basis for the in-depth development and utilization of Camellia nitidissima.

To isolate and screen a “golden flower fungus” from Hubei Qingzhuan tea for application in the microbial liquid fermentation of Siraitia grosvenorii, leverage microbial decomposition and transformation to enhance the dissolution and biotransformation of its functional bioactive components.

The isolated strain was identified based on morphological characteristics and internal transcribed spacer (ITS) phylogenetic analysis, supplemented by resequencing. The Siraitia grosvenorii substrate was subjected to static liquid fermentation with this strain at 28 °C for 8 d. The content of bioactive compounds, including mogrosides, sugars, total phenolics and flavonoids, were quantified using high performance liquid chromatography, the phenol-sulfuric acid method, the dinitrosalicylic acid method, the vanillin-sulfuric acid method, the Folin-Ciocalteu method and the sodium nitrite-aluminum nitrate method. Key enzyme activities and antioxidant capacity during fermentation were assessed using the dinitrosalicylic acid method, the Folin method and the potassium ferricyanide method.

The strain was identified as Eurotium sp.. Liquid fermentation of Siraitia grosvenorii with this strain significantly increased the content of total sugars, reducing sugars, total mogrosides and mogroside V, reaching maximum mass concentrations of 11.029, 8.390, 1.619 and 0.540 mg/mL, respectively. These values correspond to 1.029, 1.336,1.278 and 2.030 times the levels in the unfermented group. The peak activities of cellulase, hemicellulase, pectinase, α-amylase and protease during fermentation reached 20.250, 14.100, 27.513, 14.399 and 7.045 IU, respectively. The highest bioactivity was observed on the second day of fermentation, with the total reducing power reaching 0.478, the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging rate reaching 63.767%, and the α-glucosidase inhibitory activity reaching 61.604%, which were 1.046, 1.314 and 1.364 times those of the unfermented control.

Fermentation of Siraitia grosvenorii with the “golden flower fungus” effectively enhances the content of mogroside V and improves antioxidant activity. This study provides a promising microbial strain and technical foundation for advancing biotransformation technologies and product development utilizing Siraitia grosvenorii.

To compare the pretreatment methods for the determination of aflatoxin in tea by ultra performance liquid chromatography-tandem mass spectrometry.

The 3 kinds of different pretreatment methods, immunoaffinity column method, QuEChERS and multifunctional column were adopted to pretreat the tea, the aflatoxin B₁ (AFB₁), aflatoxin B₂ (AFB₂), aflatoxin G₁ (AFG₁) and aflatoxin G₂ (AFG₂) in tea were detected by ultra performance liquid chromatography-tandem mass spectrometry, and the effects of 3 kinds of different pretreatment methods on the determination results were compared. The purification effect, matrix effect, stability, repeatability, limits of detection and recovery rates of the 3 kinds of pretreatment methods were compared.

The immunoaffinity column method had low matrix effects and less impurities. The 3 kinds of different pretreatment methods exhibited a good linear relationship for aflatoxin in the concentration range of 1–60 μg/L, the correlation coefficients were not less than 0.999. The average recoveries ranged from 78.6%–107.1% with relative standard deviations of 1.3%–3.1%. The limits of detection ranged from 0.04–0.22 μg/kg. There was no significant difference in the limits of detection between immunoaffinity column method and multifunctional column method, but the results of limit of detection showed that immunoaffinity column method and multifunctional column method were better than QuEChERS method. The results obtained from the quality control samples of tea matrix after 3 kinds of pretreatment methods were used, the difference was within the acceptable range. The 3 kinds of methods could meet the experimental requirements in the detection of AFB₁, AFB₂, AFG₁, AFG₂ in tea matrix.

These 3 kinds of methods are all suitable for the determination of AFB₁, AFB₂, AFG₁, AFG₂ in tea. The immunoaffinity column method has low matrix effects and high sensitivity, and therefore can be used to determine low concentration samples. QuEChERS method is better in terms of simple operation and instrument maintenance cost saving than multifunctional column. QuEChERS method is simple and efficient, and it is suitable for large-scale samples detection.

To establish a method for determination of 21 kinds of pyrrolizidine alkaloids in tea by QuEChERS pretreatment combined with ultra performance liquid chromatography-tandem mass spectrometry.

Tea samples were first hydrated with water, extracted by 0.1% formic acid acetonitrile, purified by QuEChERS, and then filtered by microporous filter membrane, the filtrate was directly for analysis. The samples were measured in electrospray positive ion source and multi-reaction monitoring mode.

Within each specified concentration range, 21 kinds of pyrrolizidine alkaloids showed excellent linearity, with the correlation coefficient (r²) exceeding 0.998. The limits of detection were 0.03–3.00 μg/kg, limits of quantitation were 0.10–10.00 µg/kg. while the average recovery rates varied from 81.3% to 116.3% and the relative standard deviations were between 0.5% and 10.6%.

The method is simple and rapid, and can meet the detection requirements of pyrrolizidine alkaloids in tea. Meanwhile, when applied to the detection of commercially available tea samples, it is found that some samples contained lycopsamine, lycopsamine N-oxide and intermedine.

To establish a method for the determination of abietic acid, dehydroabietic acid and piperic acid content in food by liquid chromatography-tandem mass spectrometry.

By optimizing the mass spectrometry analysis conditions, the sample was extracted using acetonitrile as the extraction solvent and subjected to ultrasonic extraction, enriched and purified by a mixed strong anion exchange reverse phase solid-phase extraction column, concentrated to near dryness by nitrogen blowing, diluted with methanol and centrifuged at high speed. The solution was then analyzed by liquid chromatography-tandem mass spectrometer.

The peak shapes of 3 kinds of compounds were good, and the separation and response met the detection requirements. The linear range of abietic acid was 4–500 ng/mL, with a limit of detection of 1.0 μg/kg and a limit of quantitation of 3.0 μg/kg. The linear range of dehydroabietic acid was 20–2500 ng/mL, with a limit of detection of 2.5 μg/kg and a limit of quantitation of 7.5 μg/kg. The linear range of piperic acid was 4–500 ng/mL, with a limit of detection of 0.5 μg/kg and a limit of quantitation of 1.5 μg/kg. Within the range of 5–40 μg/kg of abietic acid and piperic acid and 15–100 μg/kg of dehydroabietic acid, the recovery rates of abietic acid, dehydroabietic acid and piperic acid were 84.9%–99.7%, 84.7%–101.9% and 88.1%–104.7%, respectively, with relative standard deviations within 10%. The method was used for actual sample analysis, detecting abiietic acid, dehydroabietic acid and piperic acid in multiple foods.

This method is sensitive, accurate, and can simultaneously determine abietic acid, dehydroabietic acid and piperic acid. It lays the foundation for developing specific migration limit standards for rosin like substances in paper packaged foods.

To investigate the developmental toxicity and molecular mechanisms of the water extracts from Ustilaginoidea virens-infected Oryza sativ [mainly containing ustiloxin A (UA)] in Danio rerio embryos.

Danio rerio embryos were exposed to 0.1, 0.5 and 2.5 mg/L of the water extracts from Ustilaginoidea virens-infected Oryza sativ (calculated based on UA concentration) for 120 h. Developmental parameters, including mortality, body length, heart rate, pericardial edema rate and spinal curvature rate, were evaluated. Quantitative real-time polymerase chain reaction was used to determine the messenger ribonucleic acid (mRNA) expression of cardiac development-related genes (Nkx2.5, Tbx5, Tnnt2, Gata4, Nppa, Nppb) and skeletal development-related genes(Col8a1a, Bmp2b, Ngs, Ihh, Shh).

Compared with the control group (Danio rerio culture medium without the water extracts), all exposure groups exhibited significantly higher mortality and pericardial edema rates. In the 0.5 mg/L and 2.5 mg/L groups, spinal curvature incidence significantly increased and body length significantly reduced. Moreover, the heart rate of Danio rerio embryos in the 2.5 mg/L exposure group significantly increased (P<0.05). Gene expression analysis revealed that in the 0.1 mg/L group, the expression of Tbx5, Nppa, Nppb, Bmp2b and Ihh was significantly downregulated. With increasing exposure mass concentrations (0.5 mg/L and 2.5 mg/L), nearly all examined key genes involved in cardiac and skeletal development were markedly suppressed.

The water extract prepared from Ustilaginoidea virens-infected Oryza sativinduces significant developmental toxicity in Danio rerio embryos, particularly impairing cardiac and skeletal development. These effects are likely mediated by the dose-dependent suppression of key developmental genes, suggesting that long-term consumption of Ustilaginoidea virens-infected rice may pose potential health risks to animals.