Search Results (148)

Background/Objectives: Tea and coffee, two of the most widely consumed beverages worldwide, play important roles in supporting overall health. Changes in the urine proteome reflect the changes in the body influenced by beverage consumption, rather than beverage metabolites. In this study, the effects of teas with different fermentation levels and black coffee on the body were explored via urine proteomics analysis. Methods: Urine samples were collected from rats before and after seven consecutive days of consuming green tea, oolong tea, black tea, Pu-erh tea, or black coffee. Both before-and-after comparisons and between-group comparisons were performed, and the samples were analyzed using liquid chromatography coupled with tandem mass spectrometry. Results: The urine proteome reflected the changes in rats after consumption of teas or black coffee for one week. Biological processes and pathways enriched with differential proteins included fat cell differentiation, lipid metabolism, glucose metabolism, fatty acid transport, and immune response. The effects of teas with different fermentation levels and black coffee on the body exhibited a high degree of specificity. Additionally, several identified differential proteins have been reported as biomarkers for diseases such as cancer and cardiovascular diseases. This suggests that beverage consumption, including tea and black coffee, should be considered in urine biomarker research. And the use of biomarker panels may be necessary to improve accuracy. Conclusions: The urine proteome provides a comprehensive and systematic reflection of the effects of all components in teas and black coffee on the body and allows for the distinction of changes in the body after consumption of teas with different fermentation levels and black coffee. Full article

The fermentation process of oolong tea is a critical step in shaping its quality and flavor profile. In this study, the fermentation degree of Anxi Tieguanyin oolong tea was assessed using image and hyperspectral features. Machine learning algorithms, including Support Vector Machine (SVM), Long Short-Term Memory (LSTM), and Gated Recurrent Unit (GRU), were employed to develop models based on both single-source features and multi-source fused features. First, color and texture features were extracted from RGB images and then processed through Pearson correlation-based feature selection and Principal Component Analysis (PCA) for dimensionality reduction. For the hyperspectral data, preprocessing was conducted using Normalization (Nor) and Standard Normal Variate (SNV), followed by feature selection and dimensionality reduction with Competitive Adaptive Reweighted Sampling (CARS), Successive Projections Algorithm (SPA), and PCA. We then performed mid-level fusion on the two feature sets and selected the most relevant features using L1 regularization for the final modeling stage. Finally, SHapley Additive exPlanations (SHAP) analysis was conducted on the optimal models to reveal key features from both hyperspectral bands and image data. The results indicated that models based on single features achieved test set accuracies of 68.06% to 87.50%, while models based on data fusion achieved 77.78% to 94.44%. Specifically, the Pearson+Nor-SPA+L1+SVM fusion model achieved the highest accuracy of 94.44%. This demonstrates that data feature fusion enables a more comprehensive characterization of the fermentation process, significantly improving model accuracy. SHAP analysis revealed that the hyperspectral bands at 967, 942, 814, 784, 781, 503, 413, and 416 nm, along with the image features H_σ and H, played the most crucial roles in distinguishing tea fermentation stages. These findings provide a scientific basis for assessing the fermentation degree of Tieguanyin oolong tea and support the development of intelligent detection systems. Full article

Oolong tea presents notable variations in taste profile and aroma characteristics under different cultivation conditions, particularly across altitudes. However, systematic investigations into the altitude-induced differences in key taste compounds and aroma composition remain limited. In this study, we examined six oolong tea cultivars, comparing their taste-related chemical constituents and aroma profiles under high- and low-altitude cultivation. Sensory evaluation, high-performance liquid chromatography (HPLC) and headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) were employed to characterize these differences. Sensory evaluation revealed that high-altitude oolong teas exhibited enhanced umami, sweetness, and floral intensity. In most cultivars, the levels of free amino acids, polyphenols, and soluble sugar were relatively higher under high-altitude conditions. HS-SPME-GC-MS identified 55 common volatile organic compounds (VOCs), with terpenes and esters comprising the largest number of compounds. Identification by partial least squares discriminant analysis (PLS-DA) combined with relative odor activity value (rOAV) screening yielded 22 candidate differential volatile organic compounds. Floral monoterpenes, including linalool, linalool oxide II and geraniol, were consistently higher in high-altitude teas, whereas most other volatiles varied primarily with cultivar rather than altitude. These chemical patterns are consistent with the sensory finding of stronger floral intensity in high-altitude samples. This study provides theoretical insights for cultivar selection and quality improvement of oolong tea grown in high-altitude regions. Full article

Wuyi Mingcong (WYMC) is a distinctive tea germplasm resource from Wuyi Mountain, known for its unique aroma and quality characteristics. However, the aroma quality of WYMC has been insufficiently studied. In this study, the aroma profiles of seven characteristic tea plant resources WYMC tea samples were characterized using sensory evaluation combined with headspace solid-phase microextraction and gas chromatography–mass spectrometry (HS-SPME-GC-MS). The results revealed that “floral,” “fruity,” “clean and refreshing,” “woody,” and “sweet” were the main aroma characteristics. A total of 37 volatile compounds were found to contribute significantly to the aroma profiles of the seven WYMC tea samples, with dihydrolinalool and (E)-β-ionone likely being the key contributors to their floral and fruity notes. Ten key volatile markers were identified as responsible for aroma differences between the Fujian Shuixian (SX) and seven WYMC tea samples. Phenylethyl alcohol, cis-3-hexenyl benzoate, δ-cadinene, nerol, and β-myrcene may be critical for the formation of WYMC’s characteristic aroma. cis-3-hexenyl benzoate and nerol may act as “broad-spectrum” aroma contributors, enhancing the overall intensity or layered nature of WYMC’s scent. The results of this study enrich the understanding of the aroma characteristics of WYMC and provide a theoretical foundation for the development and utilization of tea germplasm resources in the Wuyi Mountain. Full article

In the context of smart agriculture, the tea industry is undergoing a transformative shift toward intelligent development. As the birthplace of tea, China holds a significant position in the global tea industry, with Anxi County in Quanzhou City, Fujian Province—renowned as the origin of Tie Guan Yin—standing as the world’s largest oolong tea production area. Its intelligent transformation of the tea industry is typical and representative. However, current research on the digital literacy of farmers is not yet mature, and there is a lack of systematic research on this specific group of tea farmers, which to some extent restricts the transformation of the tea industry towards intelligent development. The level of digital literacy among tea farmers is crucial for the intelligent development and transformation of the tea industry. Improving the digital literacy of tea farmers is the key to promoting the intelligent development of the tea industry. Therefore, studying the digital literacy of tea farmers has significant practical significance. This article takes Anxi County as the research area and focuses on moderate-scale tea farmers as the research object. Based on the United Nations Global Framework for Digital Literacy and taking into account the actual situation of tea farmers, an evaluation index system and analysis framework for tea farmers’ digital literacy have been constructed from seven dimensions: equipment and software operation skills, digital information literacy, digital communication and collaboration literacy, digital content creation literacy, digital security literacy, problem-solving literacy, and professional digital literacy. Using literature review, questionnaire survey, interview, and quantitative analysis methods, a questionnaire containing the above-mentioned dimensions was designed. After collecting data, the rationality of the questionnaire structure was verified using SPSS software. The digital literacy level of 440 medium-sized tea farmers from 11 major tea-producing townships in Anxi County was measured, analyzed, and Two-Tailed correlation tests were conducted. The results indicate that there are currently six aspects of digital literacy among tea farmers that are at a moderate level, and professional digital literacy is the weakest among the seven digital literacy. The overall digital literacy level of tea farmers needs to be strengthened. Large-scale tea farmers have the conditions to apply smart agricultural equipment and technology, which can achieve intelligent and refined management of tea gardens and intelligent upgrading of the entire industry chain. Based on the research results of the seven digital literacy of tea farmers, this article proposes improvement measures corresponding to the seven digital literacy of tea farmers from the perspectives of “government, industry associations, and training institutions”, providing reference for Anxi County and other tea-producing areas in the world. Full article

Background/Objectives: Tea, the world’s second most consumed beverage after water, contains diverse phytochemicals that have garnered growing interest for their potential ability to modulate inflammasome activation. This study examined the antioxidant and anti-inflammatory properties of oolong tea (OLT) extracts, with a specific focus on their regulatory effects on NLRP3 inflammasome assembly—a critical mediator in chronic inflammatory diseases. Methods: OLT extracts were prepared from the Jin-Xuan cultivar with quantification for bioactive components (total phenolics, flavonoids, condensed tannins, and proanthocyanidins). J774A.1 murine macrophages were primed with LPS and stimulated with ATP to induce inflammasome activation. Therapeutic potentials of OLT extracts were assessed by measuring cytokine secretion, expression of NLRP3 inflammasome-related proteins (NLRP3, ASC, Caspase-1, and IL-1β), inflammasome complex formation, and ROS generation via biochemical assays, immunoblotting, and fluorescence microscopy. Results: OLT extracts, particularly at 100 µg/mL, markedly suppressed both the priming and activation phases of NLRP3 inflammasome formation. OLT treatment reduced IL-1β secretion by more than 50%, attenuated ASC oligomerization and speck formation, inhibited caspase-1 cleavage, and lowered intracellular ROS levels by approximately 50%. Conclusions: These findings suggest that OLT extracts exert potent anti-NLRP3 inflammasome activity and offer immunomodulation potential in preventing inflammation-related diseases such as infections, cancer, and neurodegenerative disorders. Further in vivo investigations, followed by clinical applications and epidemiological studies, are warranted to validate these preventive effects in human populations. Full article

Both China and Korea have significant markets for tea; however, both the availability and preference for oolong and black oolong tea vary across the two markets. Although this difference has been highlighted in previous studies, the group differences in the two markets based on preferences and sensory perceptions have not been assessed. Therefore, this study aimed to investigate the overall oolong and black oolong tea preferences based on specific characteristics of the tea samples and the sensory perceptions of young Chinese and Korean consumers residing in South Korea. Twelve tea samples were selected for on-site evaluations. A Check-All-That-Apply (CATA) method with 20 sensory characteristics was used to identify the sensory characteristics perceived, supplemented by intensity ratings for key attributes. The CATA-Penalty analysis revealed sensory characteristics that significantly impacted overall liking. The results indicated that while Chinese and South Korean consumers exhibited some differences in overall preference trends, they shared similar preferences within specific tea categories. This reflects differences in preferences between Chinese and South Korean consumers for oolong and black oolong tea beverages and the possible impact of different cultural backgrounds on consumption habits. These findings provide insights into cross-cultural sensory preferences and the impact of the cultural background on tea beverage perception. Full article

In a survey of Bajiaozhai National Forest Park (Guilin, China), several specimens of an Euseius sp. were collected. These specimens were very similar to Euseius nicholsi and Euseius oolong, based on morphological observations. However, some morphological characters, such as the body size, number of solenostomes on the dorsal plate, calyx shape of the spermatheca, the shape and number of metapodal platelet, teeth number on the fixed digit, length of setae j3, and macroseta Seg IV, Sti IV, and St IV were different between these specimens and E. nicholsi and E. oolong. To ascertain whether these morphological differences were interspecific or intraspecific variations, molecular analyses were conducted using mitochondrial DNA COI, 12S rRNA, and nuclear ITS markers. Based on the three molecular markers, minimal genetic distances were observed (COI 0–4%, 12S rRNA 0–2%, and ITS 0%) among the putative Euseius sp., E. nicholsi (collected from Bauhinia purpurea in IZGAS and from Eurya macartneyi and Ficus hispida in Shaoguan City), and E. oolong (collected from B. purpurea in IZGAS). Amblyseius swirskii was used as the outgroup. Using the maximum likelihood method, the phylogenetic tree showed that these specimens of Euseius sp., E. nicholsi, and E. oolong clustered in a single clade. Therefore, we propose that this putative Euseius sp. is E. nicholsi, and E. oolong is a junior synonym of E. nicholsi. This study demonstrates the importance of integrative taxonomy for the proper identification of phytoseiid mites. Full article

Background/Objectives: Camellia sinensis (L.) Kuntze or tea contains bioactive compounds such as catechin and caffeine, known for their antimicrobial and health-promoting properties. Colibactin-producing Escherichia coli are linked to genotoxicity in colon epithelial cells, potentially contributing to colorectal disease. This study aimed to evaluate the inhibitory effects of tea extracts (green, oolong, and black) and the phytochemicals catechin and caffeine on E. coli pathogenesis mediated by colibactin toxins, including transient infections, DNA damage, and cell cycle alterations in Caco-2 colon cells. Methods: Tea extracts were analyzed by HPLC for phytochemical content. Their antimicrobial activity against colibactin-producing E. coli (ATCC 25922) was assessed. Caco-2 cells were infected with the bacteria and treated with tea extracts or compounds. Cell viability was measured by MTT assay, DNA damage was measured by alkaline comet assay, and the expression of CDK-1, CDK-2, and Ki-67 genes was measurd by qRT-PCR. Results: Tea extracts and catechin inhibited colibactin-producing E. coli and significantly protected Caco-2 cells. Oolong tea showed the highest protection (90.78 ± 2.76%), with others maintaining viability above 80%. DNA damage was markedly reduced, and cell cycle regulation improved. All extracts upregulated CDK-1 and downregulated CDK-2, aiding in cell cycle restoration. Ki-67 expression indicated enhanced cell proliferation during infection. Conclusions: This study highlights new findings showing that tea extracts, including green, oolong, and black tea, as well as the tea compounds catechin and caffeine, can protect against DNA damage and help maintain the normal cell cycle of colon cells infected with E. coli-producing colibactin toxin. These results support their potential role in preventing and mitigating infections caused by such E. coli strains while promoting colon cell health. Full article

The objective of this study was to assess the content of selected elements—fluorine, calcium and inorganic phosphorus—in infusions prepared from selected commercial leaf teas available on the Polish market. A comprehensive analysis was conducted based on tea type and geographical origin. In addition, the Target Hazard Quotient (THQ) was calculated to estimate the non-carcinogenic health risk associated with fluoride intake from tea consumption. Methods: A total of 98 leaf tea samples were analyzed, including 55 black, 27 green, 9 oolong, and 7 white teas. Standardized brewing protocols were applied. Measured parameters included pH, calcium and inorganic phosphorus content, buffer capacity, and titratable acidity. Fluoride concentrations were determined using an ion-selective electrode. Statistical analysis was performed using non-parametric methods (Kruskal–Wallis ANOVA with DSCF post hoc test), and heatmaps were generated to illustrate the distribution of THQ across different models. Results: Black teas exhibited significantly lower pH values and higher titratable acidity, buffer capacity, and inorganic phosphorus levels compared to other tea types, indicating distinct physicochemical properties. Although all THQ values for fluoride remained well below the safety threshold (THQ < 1), the highest values were observed in elderly individuals with low body weight, particularly women consuming green tea, suggesting increased vulnerability in this subgroup. Conclusions: Among the analyzed samples, black teas demonstrated the most distinct chemical profile, characterized by the lowest pH and the highest acidity, buffer capacity, and fluoride and phosphorus content—especially in teas originating from Africa and Central Asia. While fluoride exposure from leaf tea infusions does not appear to pose a direct health risk, older adults, particularly low-weight women, may be more susceptible to potential non-carcinogenic effects and should moderate their intake of high-fluoride teas. Full article

Dancong tea is a representative type of oolong tea typically stored for over six months before sale to reduce gastrointestinal irritation. The effects and mechanisms of this storage on gastrointestinal damage remain unclear. Therefore, this study investigated hydrochloric acid and ethanol (HCl/EtOH)-induced gastric injury in mice. The results indicate that six-month-stored Dancong tea (OldT) alleviated gastric injury at low doses but showed no protective effect at high doses; in fact, high-dose OldT exacerbated injury. In contrast, fresh tea (NewT) aggravated gastric injury at both low and high doses. Hematoxylin and eosin (H&E) staining revealed that low-dose OldT significantly attenuated gastric histopathological injury. Mechanistically, low-dose OldT reduced injury via antioxidant and anti-inflammatory pathways (Nrf-2/HO-1 activation and NF-κB inhibition), and inhibiting lipid peroxidation, reactive oxygen species (ROS), nitric oxide (NO), and inflammatory mediators (iNOS, COX-2, IL-6, TNF-α). These findings suggest that storage reduces the gastrointestinal irritant properties of fresh Dancong tea, providing a scientific basis for industrial practice and guiding consumption. Full article

Taiwan accounts for 90% of the total oolong tea production and enjoys a good global reputation for its quality. In recent years, oolong tea from neighboring countries has been imported into Taiwan and sold as Taiwanese oolong at high prices. This study aimed to rapidly classify oolong tea from four geographical origins (Taiwan, Vietnam, China, and Indonesia) using an electronic nose (E-nose) combined with machine learning. Color measurements were also conducted to support the classification. The electronic nose (E-nose) was utilized to analyze the aroma profiles of tea samples. To classify the samples, five machine learning models—linear discriminant analysis (LDA), support vector machine (SVM), K-nearest neighbor (KNN), artificial neural network (ANN), and random forest (RF)—were developed using 70% of the dataset for training and tested on the remaining 30%. Gray relational analysis (GRA) was applied to measure the relationship between sensor responses and reference tea origins. Multivariate analysis of variance (MANOVA) indicated a statistically significant effect of tea origin on color parameters, as confirmed by both Pillai’s trace and Wilks’ Lambda (Λ) tests (p = 0.000 < 0.05). Among the tested models, LDA and ANN achieved the highest overall classification accuracy (98.33%), with ANN outperforming in the discrimination of Taiwanese oolong tea, achieving 98.89% accuracy. GRA presented higher gray relational grade (GRG) values for Taiwanese tea samples compared to other origins and identified sensors S4, S6, and S14 as the dominant contributors. In conclusion, the E-nose combined with machine learning provides a rapid, non-destructive, and effective approach for geographical origin classification of oolong tea. Full article

The impact of seasonality on the aroma quality of tea has been documented in various tea types, but not specifically in oolong tea. This study is the first to explore the complex relationships between seasonality, volatile compounds, and aroma quality in oolong tea. Using Headspace Solid-Phase Microextraction Gas Chromatography–Mass Spectrometry (HS-SPME-GC-MS)-based untargeted metabolomics, we analyzed 266 samples of Tieguanyin oolong tea. The data identified linalool, linalool oxides (trans-linalool oxide (furanoid) and trans-linalool oxide (pyranoid)), and their metabolites (diendiol I; hotrienol) as key seasonal discriminants. Four out of the top ten key differential compounds for distinguishing aroma scores were metabolites from fatty acid degradation, namely trans-3-hexenyl butyrate, trans-2-hexenyl hexanoate, hexyl hexanoate, and hexyl 2-methyl butyrate. Approximately one-fifth of the seasonal discriminant volatile compounds were significant in influencing aroma quality. Overall, the impact of seasonality on the aroma quality of finished Tieguanyin oolong tea is marginal. These findings enhance our understanding of the interplay between seasonal variations, volatile composition, and aroma quality in oolong tea. Full article

This study aimed to determine the caffeine and L-theanine contents in tea infusions prepared under varying fermentation degrees, brewing conditions (temperature and time), and serving methods (tea bag/loose-leaf). Infusions of six tea types (green, white, yellow, oolong, black, and Pu-erh) and various serving forms of green, white, and black tea were brewed at 80 °C and 100 °C for 2, 5, and 10 min. Contents were analyzed using reversed-phase high-performance liquid chromatography. Caffeine levels were highest in black and yellow tea (14 ± 1.0 mg/200 mL and 13.8 ± 0.2 mg/200 mL, respectively), both of which were significantly higher than the levels in green, white, and oolong tea (11 ± 2.1 mg/200 mL; 5.8 ± 0.7 mg/200 mL; and 4 ± 1.6 mg/200 mL, respectively; p < 0.001), whereas Pu-erh tea (13 ± 2.9 mg/200 mL) had caffeine levels comparable to that of black tea (p > 0.05). L-Theanine levels were highest in black and green tea (12.3 ± 2.8 mg/200 mL and 12.5 ± 2.5 mg/200 mL, respectively), and these levels were significantly higher than those in the other tea types (p < 0.001). Brewing temperature only affected caffeine levels n, whereas L-oolong tea (4.4 → 13.5 mg/200 mL, p < 0.05); theanine remained stable (p > 0.05). Longer brewing times significantly raised both components (e.g., yellow tea caffeine levels rose to 53 ± 16.9 mg/200 mL at 10 min; p < 0.05). In black tea, cup-sized bags yielded higher caffeine levels (39 ± 9.9 mg/200 mL) than loose-leaf (24 ± 7.2 mg/200 mL) and teapot bags (p < 0.001). Serving method had no effect on green and white teas (p > 0.05). In conclusion, fermentation rate, brewing conditions, and serving method were found to influence the caffeine and L-theanine levels of tea infusions. Full article

Neonicotinoids (NEOs) are a class of systemic insecticides widely used in agriculture owing to their high efficacy and selectivity. As one of the most globally consumed beverages, tea may represent a potential dietary source of pesticide residues. However, limited research has examined NEO contamination in tea and its implications for human exposure, highlighting the need for further investigation. Therefore, this study comprehensively evaluated the residue characteristics, processing effects, and human exposure risks of six NEOs—dinotefuran (DIN), imidacloprid (IMI), acetamiprid (ACE), thiamethoxam (THM), clothianidin (CLO), and thiacloprid (THI)—in Chinese tea products. According to the findings, the primary pollutants, ACE, DIN, and IMI, accounted for 95.65% of the total NEO residues in 137 tea samples, including green, oolong, white, black, dark, and herbal teas. The highest total target NEO (∑₆NEOs) residue level was detected in oolong tea (mean: 57.86 ng/g). Meanwhile, IMI exhibited the highest residue level (78.88 ng/g) in herbal tea due to the absence of high-temperature fixation procedures. Concentrations of DIN in 61 samples (44.5%) exceeded the European Union’s maximum residue limit of 10 ng/g. Health risk assessment indicated that both the chronic hazard quotient (cHQ) and acute hazard quotient (aHQ) for adults and children were below the safety threshold (<1). However, children required special attention, as their exposure risk was 1.28 times higher than that of adults. The distribution of NEO residues was significantly influenced by tea processing techniques, such as full fermentation in black tea. Optimizing processing methods (e.g., using infrared enzyme deactivation) and implementing targeted pesticide application strategies may help mitigate risk. These results provide a scientific foundation for enhancing tea safety regulations and protecting consumer health. Full article