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[前沿资讯 ] Makaibari Tea Treasures: An Infusion of the Modern into a Cup of Tradition 进入全文
World Tea News 网站
Nestled in the lush arboreal hills around Kurseong in Darjeeling District, India, Makaibari Tea Estate has evolved from plantation to legacy. Founded in the 19th century, the estate is one of the oldest and most iconic in the region, admired not only for the quality of its fine teas, but also for its commitment to sustainability, community, and innovation. Particularly since the 1980s, Makaibari has grown from a traditional estate into a globally recognized brand, with its packaged teas symbolizing biodynamic farming, organic cultivation, and ethical labor practices. It appeared to be a universal practice for Darjeeling tea companies to establish their reputations with their best teas sold abroad, and offer far lower quality tea to domestic consumers. Times are changing, and Indians want to be able, even in smaller quantities, to buy the same tea sourced from within Indian borders that is kept on the shelf in foreign boutiques. Previously, export quality tea was unavailable to the retail customer in India. The shift in demand is one of the motivating factors behind Luxmi Estates, which owns Makaibari Tea Estate, to launch a quality enhancement and consistency drive for its new packaged teas, which the company has named, Makaibari Tea Treasures.
[学术文献 ] Rapid Determination of 36 Pesticide Residues in Tea Soup Using Dispersive Liquid–Liquid Microextraction Technology Based On Hydrophobic Fatty Acid Combined With Effervescent-Assisted Extraction 进入全文
Separation Science Plus 期刊
Tea is one of the most popular beverages in the world. In tea plant (Camellia sinensis) cultivation, the application of pesticides and herbicides constitutes a common agricultural practice for integrated pest management and weed control. Researchers usually focus on the pesticide residues in tea itself and rarely study the pesticide residues in tea soup. This study presents a rapid quantitative analysis method for detecting 36 common pesticides in green tea soup. The method involves using effervescent-assisted extraction combined with dispersive liquid–liquid microextraction. Pesticides in tea soup are extracted with nonanoic acid, and during the extraction process, sodium carbonate solution (Na2CO3 solution) and sulfuric acid (H2SO4) are added to produce carbon dioxide for auxiliary extraction. The solidified substances are then dissolved in methanol and analyzed using LC–MS/MS. This study revealed that the 36 target pesticides exhibited strong linear responses across a concentration range of 1–50 ng mL−1, with correlation coefficients (R2) exceeding 0.99. The developed method demonstrated a limit of quantification (LOQ) of 0.1 µg L−1, accompanied by recovery rates ranging from 76.3% to 101.4% and relative standard deviations (RSDs) below 6.7% across all validation parameters. This approach is cost-effective, minimizes the use of organic reagents, and reduces environmental pollution. Overall, the combination of effervescent-assisted extraction and dispersive liquid–liquid microextraction is efficient for detecting pesticides in tea soup, making it suitable for routine analysis of commonly used pesticides in green tea soup.
[学术文献 ] Residue behavior, processing factor and dietary risk assessment of flupyradifurone and its metabolites during tea cultivation to consumption 进入全文
Journal of Food Composition and Analysis 期刊
The dissipation behavior and safety assessment of the commercial insecticide Sivanto® (Flupyradifurone 200 g L⁻¹ SL) in tea cultivation have not been previously studied in India. This study evaluated residue levels in fresh tea leaves and processed tea through field trials. Flupyradifurone was applied at two concentrations, 150 g a.i. ha⁻¹ and 300 g a.i. ha⁻¹ , with two applications at a 10-day interval. A modified QuEChERS technique was used for the extraction and purification of flupyradifurone and its three metabolites. Liquid chromatography-mass spectrometry (LC-MS) was used for detection and quantification. The method was validated for precision, accuracy, and linearity, with a detection limit of 0.01 mg kg⁻¹ and a quantification limit of 0.02 mg kg⁻¹ . The recovery of flupyradifurone and its metabolites ranged from 83.3 % to 113.3 %. The estimated half-life of total residues in tea leaves was 1.6 days. Brew factor was recorded as 0.06 for green tea and 0.03 for black tea. The proposed maximum residue limits (MRLs) were 9.0 mg kg⁻¹ for green tea and 30.0 mg kg⁻¹ for black tea. Based on brew factors, long-term dietary risk assessments indicated no significant health concerns when applied at recommended levels.
[学术文献 ] Phloem Redistribution of Pesticide Phenamacril in Plants Followed by Extensive Biotransformation 进入全文
Environmental Science & Technology Letters 期刊
Here, we evaluated the uptake and biotransformation mechanism of the systemic fungicide phenamacril in hydroponic/soil–plant systems. Phenamacril was preferentially accumulated in shoots with the translocation factor up to 3.5 (or 6.9) in wheat (or rice) during 144 h of the uptake kinetic experiment. Apart from upward xylem translocation, phenamacril could also be redistributed from shoots to roots (0.4%) through phloem transport and then released into the rhizosphere surrounding solution (1.7%) through plant excretion via a split-root experiment. Then, 76.4% (or 70.4%) of phenamacril was transformed to 14 (or 12) metabolites in hydroponic-wheat (or hydroponic-rice) systems after 28 days of exposure, with nine of them first identified based on nontarget analysis. The proposed metabolic pathways included hydroxylation, hydrolysis, isomerization, dehydrogenation, deamination, dehydration, decarboxylation, reduction, and conjugation reactions, which were modulated by genes overexpression of metabolic enzymes (e.g., cytochrome P450). Notably, metabolite M-157 was predicted to be more persistent in environments and more toxic to rats and aquatic organisms than phenamacril by theoretical calculation. This study highlights that phloem transport and plant excretion may result in cycling chemical contamination, and the transformation products may possess elevated toxicities, thus should be considered in estimating the contamination of pesticides in crops and environments.
[科技图书 ] The Role of Natural Antioxidants in Brain Disorders 进入全文
SpringerLink 网站
氧化应激和神经炎症被认为是帕金森氏症和阿尔茨海默氏症等各种神经系统疾病的致病因素。抗氧化剂是与氧化物种结合并消除其对生物分子造成损害的化学物质。抗氧化剂的主要来源是颜色鲜艳的水果、蔬菜、谷物、豆类和草药，其他非常有效的来源是浆果、绿茶和黑巧克力。这些化合物有可能阻碍神经退行性变，减少神经元死亡，改善记忆和认知功能。天然抗氧化剂在脑部疾病中的作用描述了各种神经保护作用及其由抗氧化剂介导的生理现象，以维持和调节针对脑部疾病的一般健康生物标志物。本书涵盖了抗氧化剂、饮食和生活方式在管理脑部疾病中的重要作用，以及它们与对抗氧化应激的传统疗法的结合使用。外源性和内源性抗氧化剂都得到了充分的探索。通过关注氧化应激作为各种脑部疾病的触发机制的作用，以及抗氧化食品与传统疗法结合使用来对抗和预防这些疾病，这对食品科学、营养学、健康科学和生理学的研究人员来说是一个有价值的来源。
[学术文献 ] Determination of tolfenpyrad residues in green tea by GC-MS/MS based on acetonitrile extractant, dispersion solid phase extraction purification 进入全文
Journal of Environmental Science and Health, Part B 期刊
Green tea is one of people’s favorite drinks. However, pesticide residues in green tea can cause harm to the human body, and therefore, detection of pesticide residues in green tea is very important. In recent years, the detection of pesticide residues in tea has become a research hotspot. In this paper, a gas chromatography-mass spectrometry/mass spectrometry (GC-MS/MS) detection method of tolfenpyrad pesticide residues in green tea was established by using acetonitrile extractant, dispersive solid-phase extraction purification, temperature programming and application retention time lock with the database. After the sample was extracted with acetonitrile, then the sample was purified by QuEChERS extraction purification tube, afterward isomer B was used as the internal standard for the determination by multiple reaction monitoring mode (MRM) of GC-MS/MS. The results indicated that the experimental data accorded with the criterion on quality control of laboratoris(chemical testing of food), and the requirements of recovery, calibration curve, precision.This method was used to detect tolfenpyrad residues in actual green tea samples in multiple batches, and the satisfactory results were obtained.
