湛江市不同茶场出品的红绿茶茶水中微量元素分析

采用原子吸收分光光度法分别测定了湛江两个茶场出品的红、绿茶茶水中的锌、铜、铁、钙、镁、锰、镉、镍、铅的含量 ,并与云南产的红、绿茶比较。结果显示 ,红、绿茶茶水中都含有较丰富的多种矿物元素和人体必需的微量元素 ,同一茶场出品的红、绿茶茶水中微量元素的含量有所不同 ,绿茶中的Mn、Ni明显比红茶的含量高 ,不同茶场出品的红、绿茶茶水中微量元素的含量也有所不同 ,浸泡次数不同微量元素的含量也不同 ,第1次浸泡的茶水中微量元素的含量明显大于第 2次浸泡的     

半夏中锌含量测定的比较研究

目的：为半夏中锌含量的测定提供一定的方法和数据参考。方法：采用原子吸收光谱法和分光光度法测定半夏中Zn的含量。结果：分光光度法测量值是53．20μg／g,火焰原子吸收光普法测定值是48．56μg／g,说明半夏中富含微量元素Zn。结论：原子吸收光谱法和分光光度法都可用于测定半夏中的微量元素锌,但原子吸收光谱法准确度高于分光光度法,因此测定半夏中的微量元素最好的方法是原子吸收光谱法。     

环境样品中微量元素硒的分析方法

对国内环境样品中微量元素硒的分析方法研究进展作一介绍。包括分光光度法,荧光分光光度法,原子吸收分光光度法,电感耦合等离子发射光谱法,极谱法,催化光度法和中子活化法。     

马兰草中微量元素研究

目的:对不同产地马兰草中微量元素含量进行考察。方法:用原子吸收分光光度法和原子荧光分光光度法测定马兰草中Cu、Se、Hg、Pb、Cd、As、Cr的含量。结果:不同产地马兰草中微量元素含量有显著性差异。结论:大转弯的马兰草中有害微量元素含量最低,有益微量元素含量最高。     

中药及其制剂中微量元素锗的分析方法进展

就国内近年来采用分光光度法，荧光分光光度法，原子吸收分光光度法，电感耦合等离子发射光谱法，极谱法，化学淬灭法，色谱法等在中药及其制剂中微量元素的分析方法进展作一综述     

紫外分光光度法测定微量元素硒

紫外分光光度法测定微量元素硒李富（黑龙江省大骨节病研究所哈尔滨１５０００１）微量元素硒的测定通常采用２，３－二氨基萘萤光测定法，但因操作条件复杂，仪器设备昂贵，有此条件的实验室不多。因此本实验介绍采用紫外分光光度法测定微量元素硒，适于基层实验室应用，...     

贵阳地区不同产地的箭叶淫羊藿微量元素及总黄酮含量测定

用原子吸收分光光度法和紫外分光光度法分别测定了贵阳地区三个不同地点同一季节采集的箭叶淫羊藿片中 1 0种微量元素及总黄酮的含量。结果表明 :虽然同是箭叶淫羊藿 ,但因产地的具体地理环境条件不同 ,其药理活性成分的含量也会出现较大差异。     

铁筷子中微量元素的研究

目的:对不同产地铁筷子中微量元素含量进行分析。方法:用原子吸收分光光度法和原子荧光分光光度法测定铁筷子中Cu、Hg、As、Cr、Se、Cd、Pb的含量。结果:不同产地铁筷子中微量元素Cu、Hg、As、Cr、Se、Cd、Pb含量有显著性影响。结论:革东村的铁筷子中有害微量元素含量最低,有益微量元素含量最高。     

粗毛淫羊藿不同部位微量元素及总黄酮含量测定

用原子吸收分光光度法和紫外分光光度法分别测定了粗毛淫羊藿根、茎、叶片中 1 0种微量元素及总黄酮的含量。结果表明 :粗毛淫羊藿全草均有药用价值 ,而根部、叶片价值更高     

山豆根中的微量元素含量分析

用原子吸收分光光度法测定了山豆根中的6种微量元素。结果表明:山豆根中含有丰富的人体必需的微量元素和极微量的有害元素镉和铅。     

芦荟茶及其茶水中常量和微量元素的测定分析

采用原子吸收法测定了芦荟茶和其茶水中钾、钠、钙、镁、铜、锌、铁、锰、锶、硒的含量 ,结果显示芦荟茶及其茶水中含有较丰富的多种矿物元素和人体必需的微量元素。无论是茶叶还是茶水中均含有较高的锰元素 ,且在热水中的总溶出率达 5 0 %以上 ,高锰是该系列保健茶的显著特点。本实验结果为探讨芦荟保健茶中微量元素与保健功能之间的关系提供了有用的数据     

茶叶中硒含量、浸出率及浸出液中硒的存在形式

本文分析了正常地区、较高硒水平地区和慢性硒中毒地区的28份茶叶样品中硒的含量,并对其在水中溶解度、存在形式以及对硒摄入量的影响进行了研究。三个地区的茶叶样品中总硒含量分别为0.085±0.030,0.206±0.186和4.027±3.033ppm。茶叶中硒的浸出率分别为20.2％,20.8％和13.5％;范围分别为11.9～30.1％,14.2～24.4％和10.0～16.9％。浸出茶水中硒的存在形式,主要有无机Se~(6+),Se~(4+)和Se~(4+)以下硒,在正常地区分别占61.4±12.2％,13.8±7.7％和24.8±14.9％,较高硒水平地区分别占59.5±18.7％,11.3±9.0％和29.2±26.4％;慢性硒中毒地区分别为36.8±8.4％,9.5±3.5％和53.7±11.3％。与当地居民的其它食物的进食量相比,饮茶水对每日硒摄入量的影响甚微。如果把慢性硒中毒地区所产的茶叶转运到低硒地区,似有一定意义。     

The fluoride content of select brewed and microwave-brewed black teas in the United States

Fluoride (F) intake is recognized to be important for dental health. Tea leaves are known F accumulators and brewed tea as well as the water used for brewing may contribute significantly to individual intake. The USDA's Nutrient Data Laboratory determined the F content of brewed and microwaved teas using geographically matched tap water samples. Two brands of top-selling regular and one of decaffeinated teabags were purchased in 36 locations and brewed either by steeping in boiled water or with microwave heating followed by steeping. The mean F content for caffeinated regular brewed tea was 373 ± 49 μg/100 g (n = 63) and for decaffeinated tea was 270 ± 46 μg/100 g (n = 34). The overall mean for F in microwaved regular tea was lower than regular brew (364 ± 40 μg/100 g vs. 322 ± 30 μg/100 g (n = 36)). In all cases, prepared tea using water from the Midwest had the highest F-values. The mean F content of the brewed teas was 3–4 times higher than the national mean of the tap water, analyzed separately (71 ± 33 μg/100 g). These data are the first nationally representative F-values for brewed teas, and will provide valuable information to the dental and medical research communities in assessment of fluoride intake and impact on dental health.     

Ethyl acetate extract from black tea prevents neuromuscular blockade by botulinum neurotoxin type A in vitro

Botulinum neurotoxin produced by Clostridium botulinum is the strongest neurotoxin and causes botulism in mammals. The current study aimed to find an inactivator for botulinum neurotoxin in black, oolong, roasted, and green teas. The ability of the four teas to inactivate the neuromuscular blocking action of botulinum neurotoxin was determined. Water extracts from black, oolong, and roasted teas protected against the toxicity of botulinum neurotoxin type A in mouse phrenic nerve–diaphragm preparations. The order of potency of the water extracts was black tea?>?oolong tea?>?roasted tea?>?green tea (no effect). The effects of several organic solvent extracts of black tea water extract were examined, and the order of potency was ethyl acetate extract?>?butanol extract?=?remaining extract?>?chloroform extract (no effect). Ethyl acetate extracts from oolong, roasted, and green tea water extracts also exhibited a stronger protecting effect than chloroform, butanol, and remaining extracts from these teas, but they had weaker protective effect than ethyl acetate extract from black tea water extract. These protective effects occurred only when each extract was pre-mixed with the toxin before the assay, and they were not modified by mixing each extract with bovine serum albumin (BSA) before adding the toxin. These results indicate that ethyl acetate extract from black tea is the best source for searching for tea-derived inactivating substance(s) of botulinum neurotoxin.     

深圳市南山区居民饮水习惯调查

目的了解深圳市居民饮水习惯。方法采用多阶段随机抽样的方法,由经过专业培训的调查者对调查对象进行一对一的问卷调查,问卷经核实后输入计算机。结果 401名入选居民,平均年龄为(39.6±10.8)岁,男女约各占一半,汉族为主,文化程度以大专为主,家庭收入在5 000~9 999元/月之间居多。调查结果表明,男性饮水摄入总量、饮茶量多于女性,豆浆及乳类摄入量少于女性,白开水、豆浆及乳类摄入人数少于女性;不同年龄段居民瓶装水、桶装水、饮料、饮茶、豆浆及乳类摄入量差异有统计学意义,瓶装水、桶装水、饮料、咖啡摄入人数差异有统计学意义;不同文化程度居民白开水、瓶装水、饮茶、豆浆及乳类、咖啡摄入量差异有统计学意义,饮茶、咖啡、豆浆及乳类摄入人数差异有统计学意义;不同家庭收入居民饮水摄入总量、饮茶、豆浆及乳类、咖啡摄入量差异有统计学意义,白开水、桶装水摄入人数差异有统计学意义;吸烟者饮水摄入总量,饮料摄入量多于非吸烟者,饮茶摄入量少于非吸烟者,吸烟者饮茶人数少于不吸烟者;饮酒者饮料摄入量多于不饮酒者,饮料、豆浆及乳类饮用人数多于不饮酒者;不同体质指数居民饮料、豆浆及乳类、咖啡摄入量差异有统计学意义,咖啡摄入人数差异有统计学意义...     

Can black tea influence plasma total homocysteine concentrations?

BACKGROUND: Polyphenols can act as acceptors of methyl groups during the metabolism of methionine to homocysteine. This may result in elevations in plasma total homocysteine (tHcy) concentrations after ingestion of polyphenol-rich beverages such as tea. OBJECTIVES: Our major objective was to determine whether regular, moderate-to-high intakes of black tea alter tHcy concentrations. We also assessed the relation between the degree of O-methylation of tea-derived polyphenols and the change in tHcy with regular ingestion of tea. DESIGN: Twenty-two subjects completed a randomized, controlled crossover study. Subjects consumed 1250 mL black tea/d (5 cups each containing 2 g tea leaves in 250 mL boiled water) and 1250 mL hot water/d for 4 wk each. Fasting tHcy concentrations and 24-h urinary excretion of 4-O-methylgallic acid (4OMGA, the major O-methylated metabolite of gallic acid) were measured at the end of each period. 4OMGA was used as a marker of overall O-methylation of tea-derived polyphenols. RESULTS: Black tea did not significantly alter mean (+/- SEM) tHcy concentrations (9.9 +/- 0.5 and 10.0 +/- 0.5 micro mol/L for the hot water and black tea periods, respectively). However, the increased excretion of 4OMGA as a consequence of black tea consumption was positively associated with the change in tHcy from the hot water period to the black tea period (r = 0.55, P = 0.008). Subjects in the bottom quartile of increase in 4OMGA excretion had a significant decrease in tHcy (-0.28 +/- 0.10 micro mol/L; P = 0.046), and those in the top quartile had a significant increase in tHcy (0.78 +/- 0.16 micro mol/L; P = 0.005). CONCLUSIONS: Overall, regular ingestion of black tea did not alter mean tHcy concentrations. However, individual differences in O-methylation of polyphenolic compounds may influence the ultimate effects of black tea on tHcy.     

Black tea is not significantly different from water in the maintenance of normal hydration in human subjects: results from a randomised controlled trial

There is a belief that caffeinated drinks, such as tea, may adversely affect hydration. This was investigated in a randomised controlled trial. Healthy resting males (n 21) were recruited from the general population. Following 24 h of abstention from caffeine, alcohol and vigorous physical activity, including a 10 h overnight fast, all men underwent four separate test days in a counter-balanced order with a 5 d washout in between. The test beverages, provided at regular intervals, were 4 × 240 ml black (i.e. regular) tea and 6 × 240 ml black tea, providing 168 or 252 mg of caffeine. The controls were identical amounts of boiled water. The tea was prepared in a standardised way from tea bags and included 20 ml of semi-skimmed milk. All food taken during the 12 h intervention period was controlled, and subjects remained at rest. No other beverages were offered. Blood was sampled at 0, 1, 2, 4, 8 and 12 h, and a 24 h urine sample was collected. Outcome variables were whole blood cell count, Na, K, bicarbonate, total protein, urea, creatinine and osmolality for blood; and total volume, colour, Na, K, creatinine and osmolality for urine. Although data for all twenty-one participants were included in the analysis (mean age 36 years and mean BMI 25·8 kg/m(2)), nineteen men completed all conditions. Statistical analysis, using a factorial ANOVA approach within PROC MIXED, revealed no significant differences between tea and water for any of the mean blood or urine measurements. It was concluded that black tea, in the amounts studied, offered similar hydrating properties to water.     

Influence of steeping conditions (time,temperature, and particle size) on antioxidant properties and sensory attributes of some white and green teas

Abstract

The influence of commonly used steeping times and temperatures, as well as leaf size on the antioxidant activity and sensory attributes of tea were studied. Five unblended white and green tea samples from China and Malawi, infused in hot (70?°C and 90?°C; 7?min) or cold water (room temperature: 15, 30, 60, or 120?min) either as whole leaves or as milled, were analyzed. Total phenolic and flavonoid contents as well as antioxidant power (ABTS assay) were measured. The results show that the maximum extraction efficiency occurs with cold water for 120?min and with hot water at 90?°C and that only in the case of teas from whole, large leaves, the extraction was greater in cold than in hot infusions. Moreover, tea infusions prepared from milled leaves have the greatest antioxidant activity. In the sensory evaluation of some of the tea infusions, white teas were perceived more fragrant than green ones and were judged as the most favorite by the majority of the judges, especially for the brew prepared in cold water from whole leaves; all infusions obtained from the milled leaves in fact have a more bitter and astringent taste.     

Inhibition by White Tea of 2-Amino-1-Methyl-6-Phenylimidazo[4,5-b]Pyridine-Induced Colonic Aberrant Crypts in the F344 Rat

There is growing interest in the potential health benefits of tea, including the anticarcinogenic properties. We report here that white tea, the least processed form of tea, is a potent inhibitor of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)-induced colonic aberrant crypts in the rat. Male Fischer 344 rats were treated for 8 wk with white tea (2% wt/vol) or drinking water alone, and on alternating days in experimental Weeks 3 and 4 the animals were given PhIP (150 mg/kg body wt po) or vehicle alone. At the end of the study there were 5.65 ± 0.81 and 1.31 ± 0.27 (SD) aberrant crypt foci per colon in groups given PhIP and PhIP + white tea, respectively (n = 12, P ? 0.05). No changes were detected in N-acetyltransferase or arylsulfotransferase activities compared with controls, but there was marked induction of ethoxyresorufin O-deethylase, methoxyresorufin O-demethylase, and UDP-glucuronosyltransferase after treatment with white tea. Western blot revealed corresponding increases in cytochrome P-450 1A1 and 1A2 proteins. Enzyme assays and Western blot also revealed induction of glutathione S-transferase by white tea. There was less parent compound and 4?-hydroxy-PhIP but more PhIP-4?-O-glucuronide and PhIP-4?-O-sulfate in the urine from rats given PhIP + white tea than in urine from animals given carcinogen + drinking water. The results indicate that white tea inhibits PhIP-induced aberrant crypt foci by altering the expression of carcinogen-metabolizing enzymes, such that there is increased ring hydroxylation at the 4? position coupled with enhanced phase 2 conjugation.