Study on the Retention Rate of Green Tea Catechins Components and Tea Polyphenol by Different Processing Technology

The aim of this research was to explore the effect of fixation,rolling,and drying processing technology on the retention rate of green tea catechins components and tea polyphenol.Different fixation processes(rotary drumfiring,microwave,steam-blasting),rolling process(weight of rolling,gently press rolling and traditional rolling),drying process(stove drying,roasting dehydration,baked fried drying) were adopted.The effect of different tea processing technology on the retention rate of catechins component and tea polyphenol was analyzed.It showed that the microwave fixation process,gently press rolling process,baked fried dry process were beneficial to keep high levels of EGCG,C,EGC,EC,ECG.

Green tea catechins inhibit microglial activation which prevents the development of neurological disorders

The over-activated microglial cells induce neuroinflammation which has the main role in neurological disorders.The over-activated microglia can disturb neuronal function by releasing inflammatory mediators leading to neuronal dysfunctions and death.Thus,inhibition of over-activated microglia may be an effective therapeutic approach for modulating neuroinflammation.Experimental studies have indicated anti-neuroinflammatory effects of flavonoids such as green tea catechins.The current research was aimed to review the effect of green tea catechins in inhibiting microglial cells,inflammatory cascades,and subsequent neurological diseases.

Effect of a Commercial Extract of Green Tea and a Pure Catechin on Two Veillonella strains

The catechin Epigallocatechin-3-O-Gallate (EGCG) which is found in of Green Tea extracts (GTE), displays a variety of microbicidal properties. It is largely believed that EGCG inhibits the growth of cariogenic and periodontopathic bacteria. Objective: In this paper we compared the inhibitory activity of EGCG and a commercial GTE on the growth of Veillonella parvula. Chlorhexidine was used as positive control. Methodology: V. parvula ATCC 10790 and a clinical isolate obtained from a periodontal disease patient were cultured in the presence of EGCG or a commercial GTE, and the measurements of bacterial growth inhibition were compared to the values obtained with 0.12 and 0.2% chlorhexidine. Results: Chlorhexidine inhibited bacterial growth, however in contrast to a previous report, neither EGCG nor the GTE showed any effect on bacterial growth. Conclusions: The data show and confirm that chlorhexidine is a growth inhibitor of V. parvula while EGCG and GTE do not display such effect.

Green tea catechins prevent obesity through modulation of peroxisome proliferator-activated receptors

Epidemiological evidence and experimental studies suggest that drinking green tea is associated with a lower risk of obesity and related diseases. However, the mechanisms of these effects are not clear. In the present study, we investigated the anti-obesity mechanisms of green tea catechins (GTCs) through modulation of peroxisome proliferator activated-receptor (PPAR) pathways in high-fat diet-induced obesity in rats. GTC supplementation significantly attenuated the increased body and liver weights and the elevated serum and liver triglyceride levels. Meanwhile, GTCs increased the PPARγ levels in subcutaneous white adipose tissue (SWAT) and decreased the PPAR levels in visceral white adipose tissue (VWAT). In addition, GTC treatment up-regulated the levels of PPARδ in SWAT, VWAT, and brown adipose tissue and increased the expression of genes involved in fatty acid oxidation in brown adipose tissue. Our results suggest that GTCs exert their anti-obesity mechanism in part by modulating PPAR signaling pathways.

Qualitative analysis of catechins from green tea GMB-4 clone using HPLC and LC-MS/MS

Objective:To identify the bioactive compounds in catechins isolation and its components from green tea GMB-4 clone.Methods:Green tea GMB-4 clones were extracted with distilled water at 90C.Samples were eluted into the column with 10%ethanol.Subsequently,the column was eluted with95%ethanol and evaporated separately.Green tea extract was identified by thin layer chromatography.Catechins were separated by the stationary phase in column chromatography using polyamide with 10%ethanol eluent and 95%ethanol.The results of isolations were analyzed by high performance liquid chromatographic(HPLC)and LCMS/MS.Analysis of catechins by HPLC was done by external standard.Results:Fraction from 10%ethanol showed that four major peaks at retention time of1.663,2.367,2.950 and 4.890,indicated the presence of four catechins components including catechin,epicatechins,gallocatechin and epigallocatechin.Whereas,fraction from 95%ethanol showed two main peaks at retention time of 5.167 and 9.82,which indicated the presence of epigallocatechin gallate(EGCG)and epicatechin gallate(ECG).EGCG(m/z 459),epigallocatechin(m/z 307),ECG(m/z 443),and epicatechin(m/z 291)were isolated and separated successfully using HPLC and LC-MS/MS.Conclusions:The HPLC and LC-MS/MS methods were successfully tuned for the qualitative analysis of green tea extract with EGCG and ECG.Four major catechins were separated and identified by LC-MS/MS,such as EGCG,epigallocatechin,ECG and epicatechin.The result of HPLC analysis showed that EGCG and ECG were main components from catechins isolation of green tea GMB-4 clone.

Effect of Drinking Green Tea on Mental State of Humans

Tea is one of the most widely consumed beverages in the world,among which green tea is most common in China and Korea.Green tea constituents possess a great value to human health wherein lots of clinical studies and investigations were conducted by researchers and experts.However,there are still increasing demands and interest on the health properties of green tea,especially its effects on mental state of human brains.Based on the collated clinical studies,green tea was used to improve mental alertness and thinking.Thus,higher consumption of green tea was associated with a lower prevalence of cognitive impairment.This review summarizes the effects of drinking green tea on the mental state of human brains.Green tea contains a unique set of L-theanine and epigallocatechin gallate(EGCG) that possess biological activities in antioxidant,anti-memory loss,and antiproliferative assays potentially relevant to the prevention and treatment of various forms of brain damage.Theanine in green tea may play a role in reducing stress.The use of highly innovative method of reading and mental behavior of the human brain's response with the intake of green tea thru neuroimaging was also covered in this review.

Applications of Green Tea Extract in Bakery Products

Green tea extract(GTE) is a rich source of tea catechins with antioxidative,anticarcinogenic and antiarteriosclerotic activities and it has been applied in food such as bakery products to provide health benefits and extend the shelf life.This review outlines the stability of green tea catechins during baking process of bakery products supplemented with GTE and the effects of GTE on the functional properties,sensory properties,physical characteristics and Maillard reaction of bakery products.

绿茶及其副产物在蛋鸡生产中的应用研究进展

在饲料禁抗和畜禽绿色健康养殖的趋势下,研究和开发新型植物源饲料原料和饲料添加剂备受关注。绿茶及其副产物含有茶多酚、茶多糖、茶氨酸和咖啡碱等多种生物活性物质,具有抗氧化、抗菌、降血脂和改善肉蛋品质等生理功能以及作为一种植物源饲料或添加剂在畜禽生产中应用的潜在价值。文章综述了绿茶及其副产物的营养成分、生物活性物质与生理功能及其在蛋鸡生产中的应用研究进展,旨在为其在蛋鸡生产中的应用提供参考。

基于近红外光谱的婺源绿茶感官品质评价

该文以不同品种和品质等级的婺源绿茶为研究对象,基于近红外光谱无损检测技术,分别建立了多品种婺源绿茶的感官评分和儿茶素含量预测模型,比较了不同预处理算法、变量筛选方法和建模方法对预测精度的影响。首先,将原始光谱预处理后,使用主成分分析进行降维处理,随后通过竞争自适应重加权采样法(competitive adaptive reweighted sampling, CARS)、随机蛙跳跃算法和变量空间迭代收缩法筛选出与感官评分和儿茶素含量有关的特征波段,分别建立了偏最小二乘法和随机森林(random forest algorithm, RF)预测模型。结果表明,感官评分最佳的预处理和变量筛选算法分别为标准正态变量变换和CARS,儿茶素含量的最佳的预处理和变量筛选算法分别为标准化和CARS,非线性RF模型效果最佳,对感官评分和儿茶素含量的预测精度分别达到了0.927和0.939,相对标准偏差值均>2,表明模型预测性能较好,鲁棒性较强。研究表明近红外光谱技术可用于不同品质等级的婺源绿茶感官评分和儿茶素含量的快速预测。

不同茶树品种“梁野炒绿”理化品质分析

【目的】探明不同品种制作的武平绿茶——“梁野炒绿”的理化成分差异,为筛选适制梁野炒绿的品种及后续产品品质提升提供理论基础。【方法】本研究对‘福云6号’‘梅占’‘乌牛早’‘龙井43’这4个品种制作的“梁野炒绿”进行了感官与生化成分鉴定。【结果】感官审评发现,乌牛早品种炒绿内质综合得分最高,极显著高于其他3个品种(P<0.01),其次是梅占品种和龙井43;生化成分鉴定表明:水浸出物含量在梅占品种绿茶中均显著高于其他品种(P<0.05),茶多酚含量在梅占和乌牛早绿茶中均显著高于其他两个品种(P<0.05);乌牛早品种炒绿游离氨基酸总量最高,酯型与非酯型儿茶素比值(1.44)、儿茶素苦涩味指数(5.68)、酚氨比(3.88)均比其他品种低;氨基酸组分分析表明,茶氨酸含量(8.971~14.942 mg·g^(-1))在福云6号中极显著高于其他品种,天冬氨酸含量(1.854~2.506 mg·g^(-1))在乌牛早中极显著高于其他品种(P<0.01),谷氨酸含量(1.690~2.244 mg·g^(-1))在梅占和乌牛早炒青绿茶中显著高于其他2个品种(P<0.05);相关性分析表明,茶叶感官审评得分与水浸出物含量呈正相关(R=0.65,P<0.05),与酚氨比、酯型与非酯型儿茶素比值(P<0.05)、儿茶素苦涩味指数呈负相关。【结论】4个品种中乌牛早最适宜制作“梁野炒绿”。

市售冷泡绿茶主要品质成分冷泡浸出规律研究

“冷泡茶”(Cold-brewing tea)因其最大程度保留了茶叶的鲜爽味且兼具饮用便利性,已成为消费者追捧的新型茶饮。文章系统研究了7个市售冷泡绿茶以及1个自制冷泡龙井茶的主要品质成分及其冷水浸出规律。结果表明,冷泡茶的含水率在4.12%~12.95%之间,差异较大;水浸出物、茶多酚、游离氨基酸和咖啡碱含量范围分别在34.06%~45.32%、23.99%~32.04%、3.03%~4.22%和2.78%~3.21%。随着冷水浸泡时间延长,茶汤中主要品质成分含量均逐渐增加。冷水浸泡40 min,所有样品的茶汤中水浸出物溶出率为19.7%~51.4%、茶多酚溶出率5.3%~19.0%、氨基酸溶出率24.4%~93.1%、咖啡碱溶出率在18.4%~39.3%。冲泡方式显著影响茶叶中茶多酚、氨基酸和咖啡碱的溶出率,冲泡20 min后茶多酚冷/热水溶出比为0.30~0.60、咖啡碱冷/热水溶出比为0.18~0.34、游离氨基酸冷/热水溶出比超过0.70,冷水浸泡茶汤中游离氨基酸溶出率较茶多酚和咖啡碱高,是冷泡绿茶口感更加鲜爽的主要原因。本研究结果可为冷泡茶产品质量标准制定和新型冷泡茶产品开发提供理论依据。

太空茶叶中矿物质及抗氧化营养成分的溶出特性研究

为研究航天工况下绿茶及红茶中钙、镁、钾、钠、γ-氨基丁酸(GABA)、没食子儿茶素没食子酸酯(EGCG)、没儿茶素没食子酸酯(ECG)溶出特性,以太空绿茶及太空红茶为原料,采用(65±1)℃去离子水模拟太空泡茶程序,梯度冲泡5次,并通过电感耦合等离子体发射光谱法测定钾、钠、钙及镁矿物质营养元素含量,采用液相色谱-质谱法测定EGCG、ECG及GABA相对含量。结果表明:矿物质元素溶出率由高到低为钾、镁、钠、钙,元素溶出率与冲泡次数呈指数函数关系,5次冲泡各矿物质元素溶出率太空绿茶分别为8698%、4425%、1795%和717%,太空红茶为9334%、3604%、2619%和52%;EGCG、ECG及GABA3种成分溶出量随浸泡次数呈线性降低关系,在相同固液比条件下太空绿茶EGCG、ECG溶出量较太空红茶高,GABA在太空红茶中溶出量较高。

茶树单宁酶CsTA的理化性质及其在绿茶饮料中的应用

茶叶中的酯型儿茶素对于绿茶滋味有着重要的影响,但是夏秋季节茶树中积累过多的酯型儿茶素会降低茶叶感官品质。前期发现的茶树单宁酶CsTA具有水解酯型儿茶素的功能,但其理化性质以及能否在绿茶饮料加工中发挥一定作用尚不清楚。在前期试验结果的基础上利用液相色谱技术对CsTA进行进一步探究。结果表明,单宁酶CsTA的最适反应温度为45℃、热稳定范围在60℃以下、最适反应pH为7.0,Mg^(2+)对单宁酶CsTA活性有明显的激活作用,Cu2+可使其完全失活,Mn^(2+)、Zn^(2+)、Al^(3+)、Fe^(3+)、Fe^(2+)、Li^(+)对单宁酶CsTA活性具有一定抑制作用,CsTA在冷冻干燥后有很好的贮存稳定性。将茶树单宁酶CsTA应用于绿茶茶汤后发现,当茶树单宁酶CsTA添加量为11μg、料液比为1∶100、作用时间20 min、温度为35℃时对绿茶茶汤中酯型儿茶素的降解效果最好。本研究为今后利用CsTA在绿茶饮料生产中降低苦涩味,提升品质提供理论参考。

3种不同外形凤冈绿茶的儿茶素、氨基酸和香气组分

为探究凤冈锌硒绿茶的品质特征,以凤冈翠芽绿茶、卷曲形绿茶和直条形绿茶为研究对象,对3种不同外形绿茶的儿茶素、氨基酸和香气组分进行测定和分析。结果表明,3种不同外形绿茶的儿茶素组分和氨基酸组分含量差异显著;儿茶素组分总量表现为直条形绿茶(155.04 mg/g)>卷曲形绿茶(152.74 mg/g)>翠芽绿茶(152.74 mg/g),氨基酸组分总量表现为翠芽绿茶(22.57 mg/g)>直条形绿茶(22.24 mg/g)>卷曲形绿茶(20.32 mg/g)。3种不同外形绿茶共检测出48种香气组分,其中翠芽绿茶39种、卷曲形绿茶37种和直条形绿茶33种。3种不同外形绿茶的苦涩味程度均较低,含有有利于提升鲜爽和甜味、减轻苦味的氨基酸组分最多的是直条形绿茶,其次是翠芽绿茶,最少的是卷曲形绿茶。苯乙醇、壬醛可能是决定凤冈锌硒绿茶香气的关键化合物。

黑茶初制中茶多酚和碳水化合物的变化

本文运用高效液相色谱分析法(HPLC),纤维素分析仪等研究了黑茶初制过程中茶多酚,儿茶素组分,纤维素和可溶性糖类的变化,结果表明,在杀青和揉捻工序中,茶多酚变化不大,儿茶素主要表现为酯型儿茶素的水解。在渥堆期间,无论是传统渥堆还是无菌渥堆,茶多酚和儿茶素总量均呈下降趋势,儿茶素各组分则呈现不同的变化规律。可溶性糖只有在传统渥堆中才呈现下降趋势,在无菌渥堆中下降的幅度很小。在干燥中儿茶素和可溶性糖转化较多.对于纤维素来说,只有在传统渥堆中才表现出下降趋势,在无菌渥堆中基本保持不变。

绿茶儿茶素体内增强小鼠的肿瘤免疫反应

研究绿茶儿茶素（Ｇｒｅｅｎｔｅａｃａｔｅｃｈｉｎ，ＧＴＣ）在小鼠体内对淋巴瘤Ｌ５１７８Ｙ免疫反应的影响。结果表明，ＧＴＣ能（１）促进对Ｌ５１７８Ｙ产生免疫反应的小鼠脾细胞的特异性增殖，这一作用在ＧＴＣ２ｍｇ／ｄ灌喂的小鼠尤为显著，增殖作用比不灌喂的高６～１０倍；（２）加强特异性ＣＴＬ的诱导；（３）增加ＩＬ－２分泌和ＩＬ－２ｍ－ＲＮＡ表达；（４）增强ＮＫ细胞活性。ＧＴＣ的上述作用可能与降低巨噬细胞的抑制活性有关。

利用单宁酶改善绿茶滋味品质的研究

为了利用外源单宁酶改善夏茶滋味品质成分和组成,实验设计了在传统绿茶加工工艺的揉捻工序中,添加不同浓度的外源单宁酶,比较不同处理的成品茶在多酚类物质、儿茶素和氨基酸含量方面的差异,分析单宁酶提高夏季绿茶品质的效果。结果表明:单宁酶处理和对照相比,茶叶中茶多酚总量无显著性差异,但儿茶素的组成变化很大,其中表没食子儿茶素没食子酸酯(EGCG)明显下降;氨基酸总量有所增加,其中谷氨酸等一些低阈值氨基酸含量增加更为明显。这些成分变化对改善夏季绿茶滋味有积极意义,在夏茶加工中添加外源单宁酶可以在一定程度上降低苦涩味,从而提高茶汤的鲜醇度。

高效液相色谱法同时测定五指山绿茶中5种儿茶素类成分

建立了同时测定五指山绿茶中表儿茶素（EC）、儿茶素（C）、表没食子儿茶素没食子酸酯（EGCG）、表儿茶素没食子酸（ECG）和表没食子儿茶素（EGC）的高效液相色谱法。色谱条件为：HIQ SIL C18 V色谱柱（250 mm×4.6 mm,5μm）;乙腈-1.5%冰乙酸体系为流动相进行梯度洗脱;紫外检测器,检测波长280 nm;流速为1.0 mL.min-1;进样量10μL;柱温为35℃。在优化条件下,5种儿茶素类成分的浓度分别在15～300、10～200、10～200、20～400和10～200μg.mL-1与色谱峰面积之间的线性关系良好;平均回收率在96.20%～99.64%之间;RSD在1.12%～2.24%之间。该方法简便、快速、准确,可用于绿茶中儿茶素的质量控制。

贵州绿茶中咖啡碱和儿茶素含量分析

对贵州省243份绿茶样品中咖啡碱和儿茶素类物质采用高效液相色谱方法进行检测。结果表明:贵州省绿茶中儿茶素含量范围为9.14%～27.28%,平均含量15.71%;咖啡碱含量为1.08%～3.33%,平均含量2.24%。各地区茶叶儿茶素品质指数多数为1000～2000,其中黔南地区的最高为1975.51;各地区的儿茶素苦涩味指数主要在8.00～17.04之间,黔西南地区的苦涩味指数最低为8.00。据此分析可得,贵州绿茶具有很高的利用价值,春茶适合开发高品质的名优茶,秋茶适合用于茶叶深加工或有效成分的提取。

薄层扫描法同时测定绿茶中的EGCG、ECG和咖啡因

在硅胶G铝箔板上，以V（氯仿）：V（丙酮）：V（甲酸）=10：5：1为展开剂，检测波长280nm，狭缝尺寸4．00mm×0．30mm，采用薄层扫描法实现了绿茶中EGCG、ECG及咖啡因的同时分离和测定．结果表明：EGCG、ECG、咖啡因分别在182-1001ng、54-702ng、54-486ng范围内与峰面积呈良好线性关系，平均回收率分别为100．6％、102．0％、77．5％，为绿茶的品质评定提供了参考方法．