Influence of region of production on clonal black tea chemical characteristics

Production of black tea from the same vegetatively propagated (VP) cultivars, in Kenya and Malawi, shows variations in both chemical composition and quality. Whereas it is possible to produce black teas with similar total theaflavins and individual theaflavins, brightness and total colour levels, black teas from Kenya generally have higher thearubigins, total volatile flavour compounds and flavour index. The black tea fermentation process is much faster in Malawi compared to that in Kenya, as evidenced by faster production of plain black tea chemical parameters, especially theaflavins. Consequently, in Malawi the maximum amount of theaflavins formation takes a shorter fermentation duration than in Kenya. Given ample fermentation duration, fermentation in Kenya produces a similar amount of theaflavins. This makes it necessary to optimise fermentation time, in different geographical regions even when the same cultivar is being processed. The other plain black tea quality parameters (thearubigins, brightness and total colour) were higher in black tea which was processed in Kenya than those processed in Malawi. However, the pattern in the changes in the individual theaflavins or theaflavins digallate equivalent followed that of total (Flavognost) theaflavins, suggesting that the flavan-3-ols patterns in tea leaf might not have been affected by the geographical area of production. The total volatile flavour compounds (VFC), Group I and II VFC and the flavour index were higher in black teas processed in Kenya, further demonstrating the fact that high grown Kenyan teas are more flavoury. In both Kenya and Malawi black teas, aroma quality declined with a long duration of fermentation. Short fermentation time is therefore a method of producing more aromatic black teas. The variations in black tea quality between Malawi and Kenya were possibly due to difference in environmental conditions, leading to different shoot growth rates and biochemical composition in the shoots.     

Influence of polyphenol oxidase activity and polyphenol content of tea shoot on quality of black tea

Variation in polyphenot oxidase activity and levels of total polyphenols and catechins with respect to different clones and shoot components, and its effect on quality of black tea (Camellia sinensis (L) 0 Kuntze, were studied. There was a wide variation in polyphenol oxidase activity of the different clones tested. The optimum fermentation time and polyphenol oxidase activity of different clones exhibited a hyperbolic relationship, viz y = 2.36 + 1129/x, where y = optimum fermentation time in minutes and x = polyphenol oxidase activity in μM catechol oxidised g^?1 acetone powder min^?1, with an r value of ?0.98, which is signi Jicant at P ≤ 0.001. A good non-linear relationship was found between polyphenol oxidase activity of ji-esh tea shoots of different clones and the theajavins content of corresponding black teas. Among different shoot components, bud and first leaf had higher levels of polyphenols and catechins than internodes. However, the polyphenol oxidase activity showed a reverse trend: the internodes exhibited a higher enzyme activity compared with other components. Formation of theajavins during fermentation of different shoot components was in good agreement with polyphenol oxidase activity. High performance liquid chromatographic analysis of the theaflavins fraction in tea brew of black teas made from different components of tea shoot showed that buds resulted in black tea with the highest amount of theaflavin gallates, whereas teas produced from internodes had the lowest amount of theaflavin gallates. A new factor, viz theaflavin digallate equivalent, was developed, and the significance of this factor for chemical evaluation of black tea quality is discussed in this paper.     

红紫芽品种的茶类适制性研究

以不同季节红叶1号、红叶2号、丹妃三个红紫芽品种（系）为供试原料制成绿茶、白茶和红茶,通过茶叶品质分析及感官审评方法综合评价了红紫芽茶树品种（系）的茶类适制性。结果表明,同一品种（系）制成的绿茶和白茶理化成分含量高于对应的红茶。绿茶中各理化成分含量最高,可溶性糖含量三季平均为4.24%~4.69%,而红茶则为3.54%~3.96%。氨基酸含量在白茶中高于绿茶和红茶,白茶中含量达3.40%以上,而红茶和绿茶中含量在3%左右。红紫芽绿茶中花青素含量夏季>秋季>春季,夏季含量为0.086%~0.115%;除了春季白茶检出痕量的花青素外,其余不同季节的白茶和红茶均未检出花青素。感官审评结果表明,白茶普遍具有优雅、浓郁的花香或果香,滋味甜醇鲜爽的特点;红茶普遍具有甜香浓郁、滋味甜醇鲜爽的特点;绿茶品质成分丰富,汤色呈红紫色。研究认为,红紫芽茶更适合制作红茶和白茶,而制成的绿茶则可以作为一种新型特异茶饮进行推广。本研究为红紫芽茶的深入利用提供了理论基础和实践依据。     

不同规格CTC红碎茶理化与香气成分比较

从感官审评、理化成分、香气成分等方面对4个规格的CTC红碎茶进行分析。结果表明,所有红碎茶干茶色泽以棕褐、茶汤以红亮为主,滋味以浓、强、鲜为突出特点,香气类型为甜香,碎茶3号感官品质评分最高。各类理化成分含量在不同规格红碎茶中有显著差异,水浸出物、茶碱和儿茶素总量随颗粒减小而降低;碎茶3号茶多酚（25.68 mg/g）、咖啡碱（43.67 mg/g）和儿茶素总量（96.93 mg/g）含量最高,碎茶5号黄酮总量（20.30 mg/g）最高。GC-MS从4个规格红碎茶中检测到醇类（44.11%~51.84%）、酯类（15.31%~18.96%）、醛类（5.99%~11.56%）等9类共100种香气物质,共有香气成分21种;碎茶3号香气成分与其他规格差异最大,香气物质种类最为丰富;碎茶2号和末茶香气成分最接近,碎茶5号香气物质种类最少。通过分析,不同规格CTC红碎茶在感官审评、化学成分和香气成分方面各有差别,初步探明不同规格CTC红碎茶的品质差异。     

Comparative responses in plain black tea quality parameters of different tea clones to fermentation temperature and duration

The amounts of black tea theaflavins, brightness, and sensory evaluations varied with clones in the order clone 6/8>SC12/28>S15/10, while thearubigins and total colour changed in the reverse order. The rates of change of these plain tea quality parameters varied in all clones causing significant (P⩽ 0.05) fermentation duration and clone interactions. Thus, the total amount and rate of development of each quality parameter is unique to a clone and a change in fermentation duration for optimal quality parameter achievement in one clone cannot be extrapolated to another clone. Although processing of black tea at low fermentation temperatures improved black tea quality, there was no significant difference between fermenting at 15 and 20°C. Long fermentation duration and high temperature favoured production of more intense coloured black teas with high thearubigin levels, which were less bright and had lower theaflavin levels. There were significant (P⩽ 0.05) interactions between fermentation duration and temperature in all the plain black tea parameters development indicating that their rates of formation and amounts formed varied with time at different temperatures. Clones 6/8 and SC12/28 plain tea quality parameters were more sensitive to temperature and duration changes than clone S15/10. Thus there are clones, which can withstand high temperature and long fermentation duration without drastic impairment of their plain black tea quality parameters.     

Ethylamine content of fresh tea shoots and made tea determined by high performance liquid chromatography

The ethylamine contents of tea shoots and made teas were derived with o-phthalaldehyde and 2-mercaptoethanol, and quantified by high performance liquid chromatography. The coefficient of variation of this method was 1.97% from eight analyses. The levels of ethylamine in tea shoots declined markedly during growth and senescence after plucking; they also declined in the extracts of fresh tea during the incubation at 37°C, but this decrease was completely inhibited by amine oxidase inhibitors. The content of ethylamine in high grade green teas was higher than in low grade teas, but was almost identical in high and low grade black tea. The mean contents of ethylamine in 22 green teas and 17 black teas were 6.76±3.07 μmol g^?1 and 6.40±1.82 μmol g^?1, respectively.     

Seasonal variations in theaflavins,thearubigins, total colour and brightness of Kangra orthodox tea (Camellia sinensis (L) O Kuntze) in Himachal Pradesh

Variations in theaflavins, thearubigins, total colour and brightness of orthodox black tea were studied for four consecutive years (1993–1996) with a view to evaluating the effects of changing weather conditions on the quality of Kangra tea. A degree of withering of 600–650 mg g⁻¹ during the first, second and fourth seasons was optimal for the development of significantly higher brightness and total colour characteristics. The quality of rainy season teas suffered owing to high chlorophyll content and low degree of withering. Hot air circulation through the withering troughs to assist evaporation of leaf moisture increased the brightness and total colour of rainy season teas. High atmospheric demand during the dry season assisted loss of green leaf moisture, but withering and brightness exhibited significant negative correlations with high relative humidity and rainfall. Summer season teas were superior in their total colour and brightness. © 2000 Society of Chemical Industry     

基于单宁酶处理原料制备的高茶黄素速溶红茶品质分析

目的 研究基于单宁酶发酵加工的红茶原料,制备高茶黄素含量的速溶红茶。方法 以速溶红茶中的茶黄素含量为主要评价指标,对红茶原料进行两种提取溶剂处理和不同茶叶状态,即茶叶和茶叶磨碎样处理,同时分析其感官品质及其它化学成分含量。结果 本研究发现用60%乙醇提取工艺制备的速溶红茶中,茶黄素含量显著高于水提取工艺,茶叶状态则是茶粉原料浸提效果显著高于茶叶原料浸提效果,且速溶红茶中茶黄素含量达到2.3%,是传统红茶原料中茶黄素的3倍,速溶红茶得率达到了38%。结论 以高茶黄素茶叶为原料,并将其磨成粉,用60%乙醇提取作为提取剂制备速溶红茶,其制备的速溶红茶富含茶黄素,为速溶茶的生产加工提供了一定的理论依据,也可以为夏秋茶资源的开发利用提供新方法。     

南茶高纬度北引对茶叶品质的影响

目的研究南茶高纬度北引后对茶类适制性及绿茶品质产生的影响。方法通过理化方法,分析同一品种茶树在高纬度北引后对其叶片厚度、鲜叶成分、不同茶类感官品质、绿茶成分及感官品质所产生的变化。结果随着纬度的增加,绿茶品质较好,而红茶品质较差;随着南茶高纬度北引,叶片厚度、氨基酸、水溶性糖、水浸出物和芳香物质(精油)总量等含量随纬度增大而增加;茶多酚含量则相反;对精油中各成分分析显示,北方茶烃类成分较多,醇类成分较少。结论本研究明确了南茶高纬度北引后茶叶品质特点及化学成分基础。     

Phenolic compounds in tea from Australian supermarkets

Phenolic compounds constitute 50–70% of tea water extract and are the main quality parameters for teas. Theaflavins (TF), thearubigins (TR) and theabrownins (TB) are the major polyphenols that determine the quality of black tea. These compounds were measured in 56 leaf teas and teabags sampled from Australian supermarkets in Queensland. The various quantities of TF, ranging from 0.29% to 1.25%, indicate a quality difference that exists among the teas studied. Low TF content in black tea may be due to over-fermenting and/or long periods of storage. The solubility of TR and TB from teabags ranged from 82% to 92%, indicating that the permeability of teabags was variable. Variable quantities of TF in Australian teas show instability and a tendency of TF to oxidize during storage. Total polyphenols in green teas ranged from 14% to 34%, indicating a large variation, which was not reflected in price. The solubility of total polyphenols from teabags has been proposed as a useful quality index of the filtering paper used for the teabags. This chemical analysis of phenolic compounds in commercial teas may be a potential tool for the quality control of Australian manufactured and imported teas in Australian markets.     

刺槐花代用茶加工工艺研究与品质分析

为筛选出较适宜生产刺槐花代用茶的工艺,促进刺槐花资源的综合利用,采用晒青、烘青、炒青、白茶、红茶5种加工工艺制作刺槐花代用茶,进行感官评价及水浸出物、可溶性糖、蛋白质、游离氨基酸组分的测定与分析,探讨不同加工工艺对刺槐花代用茶品质的影响。结果表明:炒青工艺所制刺槐花代用茶水浸出物质量分数最高,为63.15%;炒青工艺、红茶工艺所制刺槐花代用茶可溶性糖质量分数最高,分别为38.29%、37.10%;蛋白质质量分数相对稳定,集中在18.70%~20.00%;白茶工艺、晒青工艺所制刺槐花代用茶游离氨基酸质量分数最高,分别为5.26%、5.10%;共检测到22种游离氨基酸组分,含6种必需氨基酸。感官评价以红茶工艺和炒青工艺条件下的刺槐花代用茶最佳,较适宜刺槐花代用茶的制备。     

Response of some black tea quality parameters to nitrogen fertiliser rates and plucking frequencies

The effects of the rate of application of nitrogenous fertiliser and frequency of plucking (harvesting) on various black tea quality parameters and yields were compared on done 6/8. High rates of nitrogen application and long plucking intervals reduced the theaflavin content and brightness of black tea liquor. The caffeine content of the black tea increased with increasing rates of nitrogen application but decreased with increase in the plucking interval. The Group I volatile flavour compounds increased with nitrogen application rate and long plucking intervals while the Group II volatile flavour compounds and the flavour index decreased. Tasters preferred teas from shorter plucking intervals and low rates of nitrogen application. Yields increased with increasing rates of nitrogen but were lowered by long harvesting intervals. The rate of nitrogen application did not change the distribution of leaf into different standards.     

工夫红茶品质分析与综合评价

为探究中国工夫红茶主要品质成分含量特征,建立茶汤滋味品质综合评价方法。对17 个国内主产茶区工夫红茶的多酚类、氨基酸、茶色素类、香气组分等品质指标进行测定,运用主成分分析、聚类分析和偏最小二乘-判别分析（partial least squares-discrimination analysis,PLS-DA）对其品质进行综合评价。结果表明：不同产区工夫红茶的品质成分组成与含量存在明显差异,多酚类及其氧化产物是主要的品质成分,茶黄素和茶红素之和与茶褐素的比值为1.05～1.12,是其滋味鲜醇、汤色红亮的物质基础;英红、海红、信阳红、宜红、越红、黔红和祁红的可溶性糖质量分数均高于4%,是其茶汤甜醇滋味的重要物质基础;黄酮在大叶种红茶（滇红、英红和海红）中的质量分数较高且大于2.7%。醇类和醛类是主要的香气化合物,尤其是呈现甜香、花香的萜烯醇含量较高。利用主成分分析法建立滋味品质评价模型,该预测模型对红茶滋味品质评价结果与感官审评结果较为相似,存在极显著相关（P＜0.01）,相关系数为0.735;茶黄素和茶多酚含量是进行工夫红茶品质分析的重要指标。系统聚类分析显示闽红自为一类,滇红、英红和海红等大叶种红茶聚为一类,其他中小叶种红茶聚为一类。PLS-DA可将2 类不同品种工夫红茶明显区分,并获得8 种差异性指标,尤其是芳樟醇、香叶醇和己醛等,可作为区分大叶种和中小叶种工夫红茶的指标物质。该研究丰富了工夫红茶风味品质的基础理论,同时为红茶品质的科学评价提供新的思路和方法。     

Comparison of the Antioxidant Properties of Commonly Consumed Commercial Teas

The antioxidant properties of various commonly consumed commercial teas were screened and compared to check what the consumers get in commercial tea bags in the range of consume preparation conditions. It includes flavored black teas and green teas, as well as some fruit teas. Electron transfer-based assays, such as phenolic content by Folin-Ciocalteu method and cupric ion reducing antioxidant capacity (CUPRAC), were applied. Higher antioxidant activity values were obtained for green and black tea infusions in comparison to fruit teas. The correlation between FC total phenolic and CUPRAC assay for all studied teas was significant (R² = 0.871). The antioxidant power of tea infusions were also measured using cyclic voltammetry. The observed anodic waves were broadened in comparison with voltammograms of single flavonoids due to the response of several antioxidants with different oxidation potentials. The values of Trolox equivalents obtained by electrochemical approach were lower than in the CUPRAC assay; however, the increased order of the antioxidant capacity of tea infusions was the same.     

Biological and chemical factors affecting the valuations of north-east indian plains teas: I.—Statistical association of liquor characteristics with cash valuations of black teas

An attempt has been made, by using the multiple regression technique, to determine whether the term ‘quality’ of the North-East Indian plains black teas has its own single characteristic as recognisable by tea- tasters or if it is the integration of some of the other important liquor characteristics, viz., colour, strength, brightness and briskness, and to determine the influence of those liquor characteristics including quality on the ‘cash valuations’ of black teas. The multiple regression analyses showed that in general, regardless of tasters and methods of manufacture, quality of North-East Indian plains black tea was found to depend mainly on briskness, quality being increased with an increase in briskness. Cash valuations, both of crushing, tearing and curling (C.T.C.) and orthodox manufactured teas, in general, depended mainly on quality and/or briskness, cash valuation being increased with increase in quality and/or briskness.     

SBSE-GC-MS分析不同等级宁红茶的差异香气成分

宁红茶是我国最早的工夫红茶之一。为探究宁红茶的香气品质成分特征，本研究收集了不同等级（贡品、特级、一级）的宁红茶，采用国标法进行感官评价；再利用搅拌棒吸附萃取（SBSE）结合气相色谱-质谱联用仪（GC-MS）进行香气成分检测，统计分析筛选出差异香气成分；最后利用偏最小二乘法回归分析（PLS-RA）明确对不同等级宁红茶香气品质具有重要影响的差异香气成分。感官结果表明，宁红茶等级越高，整体品质更好。三个等级宁红茶中共鉴定出142种香气成分，分为9个类别，其中酯类（41.29%）和醇类（30.03%）的相对含量较高；水杨酸甲酯（217.44‰）、芳樟醇（88.52‰）、香叶醇（65.54‰）、β-紫罗兰酮（56.07‰）、叶绿醇（52.72‰）和苯乙醛（41.04‰）等是相对含量较高的单个香气成分。Tukey s-b(K)方差分析得到69个极显著差异挥发性成分（P<0.01），其中α-荜澄茄油烯、芳樟醇、芳樟醇氧化物Ⅳ、月桂烯、橙花醇、橙花醛和反-β-罗勒烯等香气成分在贡品中相对含量较高，β-环柠檬醛、茶香螺烷、己酸苄酯和己酸香叶酯等在特级茶中相对含量较高，而叶绿醇、水杨酸苄酯、己酸反...     

Responses of clonal tea to location of production and plucking intervals

Tea is cultivated in diverse environments causing yield and quality differences in its beverages. To maximise yields and quality, agronomic practices should be optimised. But agronomic recommendations are uniform in different environments in Kenya despite variations in the growth factors responsible for changes in yields and quality. Plucking is labour intensive and a costly agronomic input in tea production. Trials were conducted for ten years in five tea growing regions in Kenya to assess yields and quality responses of clone BBK 35 tea to location of production and harvesting intervals. There were different (P ? 0.05) yields in the various locations, with significant (P ? 0.05) interaction effects between locations and harvesting intervals. Yields declined in three out of five regions but increased in one location with longer plucking intervals. Yields in a geographical area of production can not be used to estimate its expected yields in other tea growing areas. Black tea theaflavins varied significantly (P ? 0.05) with geographical area of production, but other plain tea quality parameters did not vary with location. It is therefore possible to make similar black teas with similar plain tea quality parameters except theaflavins from all tea growing regions of Kenya. Tea quality improved with short plucking rounds. One way to maximise tea quality is through shortening harvesting intervals. It is necessary to establish optimal harvesting rounds in the different tea growing regions in Kenya to maximise yields and quality.     

利用色谱-质谱-计算机联用分析红茶饮料香气

利用色谱-质谱-计算机联用新技术分析测定世界3大高香红茶之一祁门红茶饮料中主要芳香物质的含量与组成以及加工中的变化,为科学分析茶饮料香气以及在茶饮料加工过程中如何优化品质风味提供了理论依据。     

Compositional analysis of teas from Australian supermarkets

Caffeine, total amino acids, water extract and moisture content are considered to be quality indicators for leaf teas and teabags. These analyses were examined in 20 leaf teas and 36 teabags sampled from Australian supermarkets. About 70% of the analysed samples showed a moisture content higher than the maximum accepted level, 6.5%, for tea storage and marketing by the tea industries and traders. Water appropriate extract of 15 samples out of 36 teabags was lower than that of the teas without teabags, which indicates that the quality of the paper used for teabags needs to be evaluated. Moreover, one of the black leaf tea samples was found to have a water extract below the lower limit of international standards.     

基于品种差异的祁门红茶品质分析

为探究茶树品种对祁门红茶品质的影响,本试验选取种植于祁门产区的‘凫早2号’、‘舒茶早’2个茶树品种鲜叶,采用传统祁门红茶加工方法制成红茶样,并进行感官审评与理化分析。结果表明,2个品种红茶整体都表现出汤色红亮、甜香浓郁的祁门红茶特征品质,但2个品种红茶香气、滋味品质有明显差异。香气化合物分析表明,芳樟醇、顺-己酸-3-己烯酯、香叶醇、水杨酸甲酯、苯乙醇、2-己烯醛等香气化合物在2个红茶样中差异较大,可能是导致2个品种红茶香气品质差异的主要原因。‘舒茶早’红茶酯型儿茶素含量显著低于‘凫早2号’红茶(P<0.05),而咖啡碱及游离氨基酸含量则显著高于‘凫早2号’红茶(P<0.05),使其滋味醇厚度、鲜爽度高于‘凫早2号’红茶。综上,同产区内不同茶树品种加工的红茶,因其次级代谢产物的差异使得红茶风味不同。