茶叶质量与矿物质,微量元素及蛋白质含量的关系

测定５份龙井茶叶质量与矿物质、微量元素及蛋白质的含量，并观察茶叶的质量和元素含量、浸泡后溶出量和溶出率的关系。常量元素有Ｎａ、Ｋ、Ｃａ和Ｍｇ、必需微量元素Ｚｎ、Ｃｕ，Ｆｅ、Ｍｎ和Ｃｒ，及毒性元素Ｐｂ、Ａｓ和Ｃｄ。茶叶中元素的含量在同一产地的茶中基本一致，元素浸出率基本相同，茶叶泡３次后，其中的元素含量极低。能溶出的元素量有限，所有茶样中能溶解在水中的成分浸出率均在３０％以上。蛋白质的含量与茶样质量有关，质量好则蛋白质含量较高；浸泡后茶渣蛋白质含量高达３５％～４０％。     

茶叶中金属元素含量的测定及其浸出特性的研究

目的研究测定不同产地12种茶叶及茶汤中的Pb、Cr、Cd、As、Al、Mn、Fe、Co、Ni、Cu、Zn、Se等金属元素含量。方法采用微波消解ICP-MS测定茶叶中元素含量,通过茶叶标准物质分析结果的验证。用沸水浸泡茶叶测定茶汤中元素含量及分析各元素溶出率。结果 12种茶叶中Pb、Cr、Cd、As 4种有毒金属含量均低于国家标准限值,Al、Mn、Fe元素含量较高,不同品种茶叶中元素含量不同且差别较大。茶叶中As、Ni、Co元素溶出率较高,一浸、二浸平均溶出率之和分别为62.3%、50.9%、45.4%;Cr、Fe、Pb元素溶出率较低,一浸、二浸平均溶出率之和低于10%;Al、Mn 2种元素溶出率相对不高,但在茶叶中含量较高,茶汤中的含量也较高。结论本文研究结果对茶叶质量控制及茶饮品的合理开发利用有重要意义,同时也为健康安全饮茶提供有益参考。     

贵州茶矿质元素含量分析与茶叶质量的关系

用原子吸收光谱法测定贵州茶叶中Ｃａ、Ｍｇ、Ｚｎ、Ｍｎ、Ｃｕ、Ｆｅ６种矿质元素的含量。结果表明，其中以Ｍｇ含量最高（１８５５．２３μｇ／ｇ），Ｃｕ含量最低（１９．５６μｇ／ｇ）。这些元素的含量排序为Ｍｇ＞Ｃａ＞Ｍｎ＞Ｆｅ＞Ｚｎ＞Ｃｕ。同时还测定了茶叶用沸水浸泡后，上述６种元素的溶出量和溶出率。     

海南苦丁茶和绿茶叶中微量元素溶出率的比较分析

采用电感耦合等离子体质谱法(ICP—MS)同时测定海南苦丁茶和绿茶叶及不同条件水浸泡液中9种微量元素(Mn、Fe、Co、Ni、Cu、Zn、Mo、Cd、Pb)的含量,并计算出茶叶水浸泡液中各微量元素的溶出率。结果表明,海南苦丁茶和绿茶茶叶中元素的溶出率受浸泡条件的影响,同条件下,茶叶中不同元素的溶出率存在一定差异,其中Zn、Ni、Co元素的溶出率较高,在30%~70%之间,Fe元素溶出率较低,为3%~5%之间。该研究结果有利于人们认清海南苦丁茶与绿茶的实际功效。     

利用X—荧光光谱仪对14种茶叶及茶汤中不同元素进行定量分析

以14种市售的不同价格、不同产地、不同品级的茶叶为供试材料,利用X—荧光光谱仪对其所含元素成分进行定量分析,同时也对4种不同产地的茶叶浸泡,取不同时间段、不同层的茶水进行元素含量分析,此外还利用显微红外光谱仪对3种不同品种茶叶的有机官能团进行了测定。结果显示,不同品种茶叶中所含元素种类基本一致,但其含量存在一定差异,大多数元素在冲泡的前20 min便溶出到茶汤中、并大多集中在中上层。而3种茶叶中的有机官能团却基本相同。本实验结果为进一步研究茶叶的保健作用和冲泡方式等提供了较为科学的资料和数据。     

海南苦丁茶和绿茶叶子中微量元素溶出率的比较分析

采用电感耦合等离子体质谱法(ICP_MS)同时测定海南苦丁茶和绿茶叶及不同条件水浸泡泣中9种微量元素(Mn、Fe、Co、Ni、Cu、Zn、Mo、Cd、Pb)的含量,并计算出茶叶水浸泡液中各微量元素的溶出率.结果表明,海南苦丁茶和绿茶茶叶中元素的溶出率受浸泡条件的影响,同条件下,茶叶中不同元素的溶出率存在一定差异,其中Zn、Ni、C0元素的溶出率较高,在30%～70%之间,Fe元素溶出率较低,为3%～5%之间.该研究结果有利于人们认清海南苦丁茶与绿茶的实际功效.     

不同冲泡条件下普洱茶稀土元素析出水平及其影响因素分析

目的了解不同冲泡条件下普洱茶稀土元素析出水平及其影响因素,评估人群经普洱茶摄入稀土元素健康风险。方法以2013—2015年广东省广州市售普洱茶稀土元素监测结果为基础,根据稀土元素含量将茶叶样品分为0~2.0、 2.0~5.0和 5.0 mg/kg 3个层级,从每个层级中随机选取5份普洱茶,每份50 g,充分混匀后制成1份总重量为750 g的混合样品,模拟普洱茶在餐饮消费环节及功夫茶冲泡方式,开展茶汤冲泡实验,采用电感耦合等离子体质谱法测定冲泡后茶渣、冲泡用水以及冲泡茶汤中稀土元素含量。结果餐饮消费环节茶叶冲泡方式下,稀土元素从普洱茶析出至茶汤的平均比例为5.73%,冲泡过程中普洱茶稀土元素析出水平受茶叶量、水温、时间3个因素的影响,析出率与茶叶量呈反比,与冲泡间隔时间和水温呈正比。功夫茶冲泡方式下,稀土元素从普洱茶析出至茶汤的平均比例为7.01%,以第3泡茶茶汤稀土元素析出率最高(1.80%~3.13%)。结论不同冲泡方式下,稀土元素从普洱茶析出至茶汤中的比例较低,人群经普洱茶摄入稀土元素的量很少,按照消费者日常饮茶习惯,经饮用普洱茶汤摄入稀土元素产生健康风险的概率很小。     

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     

牛蒡茶中微量元素溶出率及化学形态研究

目的:通过对牛蒡茶及浸泡液6种微量元素含量的检测,比较不同实验条件溶出率的差异。方法:采用不同浸泡水温和浸泡时间、不同浸泡次数及牛蒡茶清洗前后和浸泡液消化与否处理,用原子吸收法测定牛蒡茶及待测液的6种微量元素含量,比较溶出率的差异元素存在化学形态的关系。结果:牛蒡茶微量元素含量高,溶出率的顺序钙>锶>锰>锌>铜>铁,并且与浸泡时间和次数密切相关,溶出率高低与存在形态也相关。结论:结合微量元素含量和溶出率,牛蒡茶是一种很好的健康的微量元素补充食品,有开发利用价值。     

原子吸收法测定茶叶中铅铜砷含量及其溶出特性

目的：探讨3种茶叶金坛**、茅山**、炒青不同浸泡时间和不同冲泡次数铅铜砷的溶出特性。方法：采用微波消解、原子吸收法测定了这3种茶叶中铅铜砷的含量。并用茶叶标准物质(GBW07605)对测定方法的准确度进行了验证。结果：结果表明方法的回收率介于90％～110％之间，结果准确可靠。结论：茶叶中不同元素在不同浸泡时间和不同浸泡次数时其溶出特性各不相同。     

SPME-GC/MS结合主成分分析检测竹叶青茶挥发性香气成分

目的 建立SPME-GC/MS检测竹叶青茶挥发性香气成分的方法,结合主成分分析法探究茶叶特征风味成分。方法 通过系统考察程序升温、载气流速、溶剂延迟时间等GC/MS条件和萃取头种类、萃取时间、萃取温度等SPME条件,确定了最佳试验参数;分析竹叶青茶的VFCs,并采用主成分分析提取其特征风味成分。结果 鉴定出109种VFCs,主要为醇类、醛类、酮类、酯类和烷烃类。结论 SPME-GC-MS法能够有效提取、分离、检测茶叶挥发性香气成分;主成分分析法有助于综合评价茶叶特征风味物质,可用于茶叶的鉴别。     

茶叶中微量元素Cr、Cu、Fe、Mn、Ni、Zn的溶出率及化合态研究

用电感耦合等离子体－光发射光谱法（ＩＣＰ－ＯＥＳ）测定市售茶叶中Ｃｒ、Ｃｕ、Ｆｅ、Ｍｎ、Ｎｉ、Ｚｎ等微量元素的含量及各元素沸水溶出率,平均溶出率分别为Ｃｒ３９．８％、Ｃｕ４２．５％、Ｆｅ８．６％、Ｍｎ４５．５％、Ｎｉ８７．１％、Ｚｎ７１．０％。溶出率随浸泡次数增加而降低,总溶出量中８０％的Ｃｒ、Ｃｕ、Ｍｎ、Ｎｉ、Ｚｎ及６０％的Ｆｅ在第一次浸泡中溶出。另外测定了６种元素在茶水中的化学形态,其中有机态     

Tea and coffee as sources of some minerals in the New Zealand diet

Daily intakes of tea and coffee of a representative sample of adult New Zealanders (865 men and 1100 women) were calculated from 24-h dietary recalls. The mineral concentrations in tea and coffee samples were determined by atomic absorption spectrometry and used to estimate daily mineral intakes from these beverages. More than 80% consumed tea and about 60% consumed coffee on the day of the recall. The men drank significantly more tea than the women (p less than 0.001), but coffee intakes were similar. The results indicate that for New Zealand adults tea is a very good source of manganese and it also contains appreciable amounts of potassium. Coffee is a better source of potassium than tea, has appreciable amounts of magnesium, and may contribute significantly to manganese intakes in some instances. The amounts of copper, zinc, sodium, calcium, and iron extracted from tea leaves and coffee beans in the brewing processes are too low to be of any nutritional significance but minerals in the water used in their preparation may make a significant contribution to dietary intakes.     

Determination of antioxidant activity,rutin, quercetin,phenolic acids and trace elements in tea infusions: Influence of citric acid addition on extraction of metals

Antioxidant activity of tea, content of bioactive compounds (rutin, quercetin, phenolic acids including: gallic, chlorogenic, protocatechuic, p-coumaric, caffeic, ferrulic, syringic and sinapic as well as other selected organic acids) and trace elements (Mn, selected as a metal playing a role in oxidative metabolism; Al; Cd; and Pb – the so-called heavy or noxious metals) were studied as these parameters greatly influence the quality of tea infusions. A number of different samples were tested including white, green, black and lemon-flavored teas, as well as the Red Lapacho tea. Antioxidant activity was measured using DPPH and ABTS tests, and a strong correlation between obtained results was observed. Infusions made from lemon teas packed in bags showed increased levels of rutin, quercetin and phenolic acids. Nevertheless, the positive effect of the increased level of phenolic compounds extracted is also connected with higher level of extracted noxious elements. Citric acid added to tea and herbal Red Lapacho infusions significantly increased Al, Cd, and Pb trace elements concentrations. Nevertheless, the infusions prepared from the lemon tea bags contained even the 10–70-fold higher content of these elements. On the other hand, addition of citric acid to tea infusions increased amount of extracted Mn only in black teas and Red Lapacho.     

从绿茶中同时提取茶多酚和咖啡碱

以绿茶为原料，同时提取茶多酚和咖啡碱，对影响浸提过程的因素进行了分析。结果显示：随着浸提时间的增加，浸提液中茶多酚和咖啡碱的含量逐步增加；随着浸提次数的增加，浸提液中茶多酚和咖啡碱的含量逐渐减少，并探讨了ｐＨ对茶多酚钙沉淀的影响。     

茶中氟化物安全性的讨论 --历史与现实的回顾

针对人们对待食品安全的2种不同态度,回顾了茶型氟中毒的出现及研究历史,茶树以及茶产品的氟含量特点;主要茶消费国的饮茶史及茶文化特征。通过文献分析认为,使用粗老茶制造的某些红茶品种、砖茶、速溶茶和茶饮料有可能导致饮茶者的氟损害。基于茶的文化特征,茶产品和饮茶方式的改变,绿茶多酚保健作用研究结果的深入人心,氟中毒的缓慢进程以及氟中毒症状的非典型性使人们忽视了使用粗老茶制造的茶产品的安全性。提出了加强茶型氟中毒研究的方向与重点,以及制定茶标准的建议。     

不同产地茶叶矿物质元素含量的调查分析

选取海南、福建等四个产地不同品种茶叶,测定其中水分、灰分等含量,并采用电感耦合等离子体原子发射光谱法(ICP-AES法)对10种茶叶中的17种常量和微量矿质元素含量进行分析。结果表明,不同种类茶叶的水分含量在6.4%～8.9%之间,灰分含量在4.0%～16.5%之间。不同产地的特产茶叶中17种矿质元素含量丰富,产地不同对茶叶常量元素与微量元素组成影响不大,所测得10种茶叶中元素含量由高到低依次为常量元素钾、钙、硫、镁、锰、铁和微量元素锌、锡、钡、铜、钠、镍、钪、铬、钴、镧、锂等。     

Anti-hyperglycemia properties of Tea (Camellia sinensis) bioactives using in vitro assay models and influence of extraction time

Tea (Camellia sinensis) has well-known health benefits, which are attributed to its polyphenolic metabolites. This research explored the potential of regular tea consumption and influence of extraction time typically used in daily consumption of tea, as a therapeutic dietary support for potential management of early stage type 2 diabetes using in vitro assay models. Extraction times of 2 and 5 minutes were compared. The 5-minute extraction time had significantly higher total phenolic content compared with the 2-minute extraction time. Choice Darjeeling 5-minute extraction yielded the highest amount of total phenolics (299.6 ± 5.9 mg/g), followed by Tazo Black 5-minute extraction (240 ± 9.7 mg/g), whereas Bigelow Green 2-minute extraction had the lowest total phenolic content (53 ± 8.2 mg/g). 1,1-Diphenyl-2-picrylhydrazyl scavenging-linked antioxidant activity was high (81-91%) for all types evaluated, and for most samples it was influenced by the extraction time. Similarly, high in vitro α-glucosidase inhibition was observed in almost all the samples assayed, and for most samples the 5-minute extraction had significantly higher inhibition compared with the 2-minute extraction time. The most fermented teas showed highest α-amylase inhibition: Choice Darjeeling 5-minute extraction had the highest inhibition (84.1%), followed by Tazo Black 5-minute extraction (71.6%). Angiotensin converting enzyme inhibition was not observed in any sample. Overall, the 5-minute extraction time was found to have more relevance for potential benefits for managing hyperglycemia than the 2-minute procedure. This research suggests that tea offers an attractive potential strategy to regulate postprandial hyperglycemia toward an overall dietary support for type 2 diabetes management.