Total polyphenols,catechin profiles and antioxidant activity of tea products from purple leaf coloured tea cultivars

Black (aerated) and green (unaerated) tea products, processed from 10 green and 18 purple leaf coloured cultivars of Kenyan origin, and two tea products, from the Japanese cultivars, Yabukita and Yutakamidori, were assayed for total polyphenols (TP) content, individual catechin profiles and in vitro antioxidant capacity (AA). In addition, the phenolic content of the tea products was determined using the Folin–Ciocalteu phenol reagent. Catechin fractions were identified using reverse phase high performance liquid chromatography (HPLC) with a binary gradient elution system.The AA% of the tea products was determined using a 2,2′-diphenyl picrylhydrazyl (DPPH) radical assay method. The results showed that TPs, catechin profiles and antioxidant activities were significantly (p ? 0.05) higher in unaerated than in aerated teas. Tea products from the purple leaf coloured tea cultivars had levels of TPs, total catechin (TC) and antioxidant activities similar to those from the green leaf coloured cultivars, except for teas from the Japanese cultivars that were very low in the assayed parameters. Caffeine content was significantly (p ? 0.05) lower in products from the purple leaf coloured cultivars than in those from the green leaf coloured tea cultivars. Antioxidant activity (%) was higher in tea products from the Kenyan germplasm than in those from the Japanese cultivars. Antioxidant potency of tea products was significantly (r = 0.789⁷, p ? 0.01) influenced by the total anthocyanin content of the purple leaf coloured cultivars. Cyanidin-3-O-glucoside was the anthocyanin most highly correlated with AA% (r = 0.843⁷, p ? 0.01 in unaerated tea). Total catechins in the unaerated products from the green leaf coloured tea cultivars were also significantly correlated with antioxidant capacity (r = 0.818⁷, p ? 0.01). Results from this study suggest that the antioxidant potency of teas is dependent on the predominant flavonoid compound, the type of tea cultivar and the processing method.     

3种紫芽茶不同成熟度芽叶特性及生化成分分析

目的 研究不同成熟度紫芽茶芽叶特性及生化成分相关性。方法 以思茅茶树良种场资源圃的紫娟、丹妃、水塘黑茶3个品种为原料，采用茶树种质资源描述规范法、高效液相色谱法分析茶树品种、芽叶特性与成熟度对茶叶内含成分的相关性。结果 供试样内含成分随成熟度呈现不同程度的显著性差异，其中花青素含量与芽叶红紫色深浅程度呈正相关，与成熟度呈负相关；茶多酚、咖啡碱、儿茶素、水浸出物同成熟度呈现显著性负相关；不同成熟度氨基酸含量变化1.09%~5.85%，其中含量最高的是水塘黑茶，其次是丹妃；咖啡碱含量2.58%~5.76%，其中含量最高的是紫娟，其次是丹妃；茶多酚含量6.36%~31.21%、花青素含量0.14 mg/g ~3.63 mg/g、儿茶素含量2.42%~24.03%、水浸出物含量22.93%~41.30%，其中含量最高的均是丹妃。结论 紫色品种茶中的内含成分丰富，具有较高的茶多酚、咖啡碱、氨基酸和儿茶素，丹妃内含成分含量较高，可作为高产优质、高花青素茶树品种的选育对象。     

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。     

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.     

不同类型沱茶品质与特征性成分分析

目的 探明不同类型沱茶的品质和特征性成分。方法 本文采用高效液相色谱、感官审评、Lab颜色模型等方法,比较分析供试沱茶的主要品质成分、干茶色泽和感官品质,结合多元统计学方法明确不同沱茶的特征化学物质组成。结果 云岭沱茶的感官审评综合得分高于其他沱茶,其汤色亮度和叶底嫩度优于其他沱茶,下关沱茶以儿茶素、表儿茶素、表儿茶素没食子酸酯含量较高,而茶黄素含量较低为特征,山城沱茶以茶红素含量较高,而水浸出物、咖啡碱、没食子酸含量较低为特征,云岭沱茶以茶黄素、茶多酚、表没食子儿茶素没食子酸酯、表没食子儿茶素、没食子酸、咖啡碱含量较高,而茶红素、茶褐素、儿茶素含量较低为特征,与沱茶感官审评得分呈显著正相关的生化成分有茶多酚、咖啡碱、没食子酸、茶黄素、表没食子儿茶素、表没食子儿茶素没食子酸酯。结论 不同类型沱茶生化成分的含量与组成特征差异较大。     

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.     

A model for predicting black tea quality from the carotenoid and chlorophyll composition of fresh green tea leaf

The plant pigment (carotenoid and chlorophyll) composition of fresh green leaf of tea for a selection of clones was studied in relation to the quality of black tea produced from processing the same green leaf. The plant pigment composition of the green leaf for nine Kenyan clones was monitored by HPLC at 450 nm. Using discriminant analysis it was shown that clones could be distinguished from one another on the basis of their green leaf plant pigment composition. Using step-wise multiple regression analysis, a linear relationship was established between the levels of six green leaf plant pigments peak 5 (neochrome), peak 17 and 18 (isomers of lutein and/or lutein epoxide), peak 23 (chlorophyll b type compound), peak 26 (aurochrome) and peak 28 (β-carotene)) and the quality of the manufactured black tea for the selected clones as assessed by tea tasters' evaluations. The model had an adjusted R-square value of 0.912 and was significant at P≤ 0.05. The value of the relationship as a means of predicting black tea quality is discussed.     

茶树新品系苦茶21-1主要品质成分分析

以新品系苦茶21-1为供试材料,以国家级良种福鼎大白茶、槠叶齐和省级良种潇湘1号为对照,测定4个品种红、绿茶的主要品质成分,并结合感官审评进行分析。实验结果表明,新品系苦茶21-1所制绿茶,外形条索弯曲紧细、色泽绿润,汤色黄绿明亮,果香浓郁,滋味鲜爽,香气和滋味尤其突出;所制红条茶外形乌黑油润,汤色红艳明亮,香气甜香醇正,滋味甜醇,"冷后浑"明显,乳状络合物呈橙黄色。红、绿茶主要品质成分含量分别为水浸出物38.26%、44.22%,茶多酚19.40%、30.38%,游离氨基酸5.01%、5.04%,咖啡碱5.11%、5.09%;红、绿茶中咖啡碱含量均高达5%以上,可能属于茶树高咖啡碱优异资源;绿茶儿茶素品质指数高于福鼎大白茶,红茶TR/TF值为11.2,茶黄素和茶红素比例优。茶树新品系苦茶21-1具有加工优质绿茶和优质红茶的品种特征,尤以红茶品质突出,有较高的红茶育种价值。     

Changes in theanine and caffeine contents of black tea with different rolling methods and processing stages

Theanine is a specific amino acid in tea, which has positive effects on health. Theanine contents of different grade Turkish teas, variations in the theanine content during tea processing, and the effects of different rolling processes on theanine content were determined. Theanine content of Turkish tea varying between 0.32 and 0.43 % has been reported for the first time by this study. Theanine content decreased in all processing steps from 10.0–3.42 to 7.73–3.97 mg g^?1 dw in Orthodox and Cay-Kur methods, respectively. In both methods, the highest theanine loss (almost 50 %) was observed in the withering step, which was followed by drying step. Caffeine content of Turkish tea was determined varying between 1.8 and 2.2 %. While the caffeine content increased in the withering step, it decreased in other steps. The correlation between theanine and caffeine contents was evaluated. A high correlation (R ² = 0.87) between the caffeine and theanine contents was found in teas classified by Cay-Kur method, and caffeine/theanine ratio was found to be around 5.3 in general.     

Comparison of the main compounds in Fuding white tea infusions from various tea types

The purpose of this study was to compare the main components, and particularly catechins, caffeine, theanine, free amino acids, and water extracts, in Bai Hao Yin Zhen, Bai Mu Dan, and Shou Mei Fuding white tea infusions brewed at different temperatures, and their contributions to taste were estimated by dose-over-threshold value. Infusion temperature had a distinct effect on the main components extracted, and 100 °C was found to be optimal for extracting catechins and caffeine. However, the effect of temperature on theanine, free amino acids, and water extracts varied with tea type. Bai Mu Dan and Shou Mei yielded a higher content of the major compounds than did Bai Hao Yin Zhen. Thus, infusion temperature had a large effect on extracting the main compounds, and the differences in content between the three white teas presumably reflected differences in the harvest time, processing method or leaf shape.     

茶叶中有效成分综合提取的研究

以绿茶为原料，采用ZJL大孔离了交换树脂和ZJX大孔吸附树脂从茶叶的浸提液中提取茶氨酸、咖啡因、茶多酚和茶多糖。通过对树脂的静态、动态吸附性能的实验研究，确定了咖啡因、茶氨酸、茶多酚及茶多糖联合分离提取的工艺。研究结果表明：该工艺能有效的从茶叶中提取咖啡因、茶氨酸和茶多酚，提取的咖啡因纯度达83．23％，提取率为1．9％，茶氨酸纯度达85．43％，提取率为0．94％，提取的茶多酚纯度达95．62％，提取率为12．35％，且茶多酚中的咖啡因含量低于0．7％，茶多糖的纯度达51％，提取率为1．1％。     

不同等级烘青绿茶生化成分及抗氧化能力的研究

：目的 研究3个不同等级烘青绿茶的生化成分、感官品质及抗氧化活性。方法 使用分光光度计测定3种茶样中总黄酮、茶多酚、氨基酸和咖啡碱的含量,利用清除二苯代苦味酰基自由基（1,1-dipheny-2-picryhydrazyl free radical, DPPH）法测定了其抗氧化活性,并进行感官评价。结果 3个等级绿茶总黄酮、茶多酚、氨基酸和咖啡碱含量差异显著（P＜0.05）,茶多酚随着茶样等级的降低而升高,咖啡碱的含量则相反,而氨基酸和黄酮是波动变化;不同等级绿茶的半抑制浓度（half maximal inhibitory concentration, IC50）差异显著（P＜0.05）,且IC50随着等级的降低而下降;感官评价得分随着等级的降低而降低;3种茶的抗氧化活性与其茶多酚含量成极显著正相关P＜0.01）,与咖啡碱的含量和感官审评得分呈极显著负相关（P＜0.01）。结论 3个等级的炒青绿茶抗氧化性随着等级的降低而升高,且与其主要生化成分呈显著相关。     

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.     

杀青方式对秋季黄金芽绿茶品质的影响

该研究以秋季黄金芽鲜叶为原料加工绿茶,比较滚筒、蒸汽和微波三种不同杀青方式对其品质的影响。感官评估结合品质成分分析表明,三种杀青方式所制秋季黄金芽绿茶均品质优异,但不同杀青方式处理的茶叶色泽、香气、滋味存在较大差异。滚筒杀青处理的干茶色泽最绿,香气最优,栗香明显,氨基酸含量比蒸汽和微波杀青分别高11.01%和5.20%,茶多酚含量低3.54%和3.94%,滋味醇和鲜爽;蒸汽杀青处理后滋味得分最高,拥有最高的茶氨酸（7.69 mg/g）和最低的咖啡碱（27.91 mg/g）,同时电子舌结果表明,其鲜味值、丰度均最大,苦味值最小;电子舌滋味属性与化学成分相关性分析表明,秋季黄金芽绿茶茶汤鲜味值与茶氨酸含量有显著正相关（p<0.05）,相关系数为0.99;苦味值与苦味儿茶素含量有显著正相关性（p<0.05）,相关系数为0.99;此外,不同杀青方式的黄金芽绿茶对不同自由基的清除能力不同,总抗氧化能力依次为微波杀青（0.83）>蒸汽杀青（0.80）>滚筒杀青（0.66）。综上所述,滚筒杀青滋味醇和,香气高长;蒸汽杀青滋味醇厚,色泽黄绿。虽有所侧重,但所制秋季黄金芽绿茶均体现了其良好的品种优势。     

Column-chromatographic extraction and separation of polyphenols, caffeine and theanine from green tea

A highly efficient column-chromatographic extraction (CCE) followed by sequential adsorption to extract and separate bioactive compounds from green tea was developed. Tea powder was loaded into columns with 4-fold solvents and eluted through a cyclic CCE. High-quality tea extracts with greater than 90% extraction efficiencies of polyphenols, epigallocatechin-3-gallate, caffeine, theanine and polysaccharides were obtained with 4-fold water circulated five times among different columns at 70 °C. Similar results, except for low polysaccharide extraction (35.5%), were obtained with 4-fold 30% ethanol circulated three times at room temperature. The highly concentrated water extraction was directly passed through columns of polyamide, DM130 macroporous and 732 ion exchange resins, resulting in high-purity polyphenols (99%), caffeine (98%) and theanine (98%) after simple purification of the eluates from each column. This method uses simple equipment, minimum solvents and can be used for both quantitative analysis and continuous preparation of high-quality tea extracts and bioactive compounds.     

杀青方法对紫色芽叶加工绿茶品质的影响

目的：探讨紫芽绿茶的最佳杀青方法。方法：以自选紫芽品系9803的一芽二、三叶为原料,分别用微波、锅炒、蒸汽、热风4种杀青方法对鲜叶进行杀青处理制备绿茶,并选取具有代表性绿茶样进行感官审评、滋味品质和香气品质分析。结果：4种杀青方法中,微波绿茶样感官审评的综合得分最高（89.65）,且微波绿茶样的主要理化成分——水浸出物、茶多酚、花青素、氨基酸和咖啡碱保留量显著高于其他3种绿茶（P＜0.05）;且酚氨比值、酯型儿茶素与总儿茶素的比值均为最低,分别为12.18和0.72。结论：4种杀青方法中以微波杀青工艺制备的紫芽绿茶品质最优。     

信阳毛尖茶的化学成分

信阳毛尖茶是中国传统名茶之一,品质优异。对信阳毛尖茶的主要化学成分进行了综述和分析。结果表明,信阳毛尖茶的茶多酚含量、儿茶素含量及非酯型儿茶素比例较高,氨基酸含量、咖啡碱含量、可溶性糖含量也比较高,形成了信阳毛尖茶鲜浓、爽口、耐泡的滋味特征;叶绿素含量高于多数嫩度相近的名绿茶,使其具有干茶色泽翠绿的品质特征;信阳毛尖茶还含有丰富的无机元素。     

Characterization of anthocyanins in Kenyan teas: Extraction and identification

Characterization and quantification of anthocyanins in selected tea cultivars processed into black (aerated) and green (unaerated) tea products was carried out in this study. The anthocyanins were extracted from tea products processed from a number of newly bred purple leaf coloured Kenyan tea cultivars (Camellia sinensis) using acidified methanol/HCl (99:1 v/v). Extracted anthocyanins were purified by C₁₈ solid phase extraction (SPE) catridges and characterised by HPLC-UV-Visible. They were identified according to their HPLC retention times, elution order and comparison with authentic standards that were available. Total monomeric anthocyanins were determined by the pH-differential method. Although the tea cultivars gave different yields of anthocyanins, the unaerated (green) teas had significantly (p ? 0.05) higher anthocyanin content than the aerated (black) teas. This was attributed to the degradation of anthocyanins by polyphenol oxidase products (catechin O-quinones) formed during the auto-oxidation (fermentation) process of black tea manufacture. Of the six most common natural anthocyanidins, five were identified in the purified extracts from purple leaf coloured tea, in both aerated (black) and unaerated (green) teas namely; delphinidin, cyanidin, pelargonidin, peonidin and malvidin. The most predominant anthocyanidin was malvidin in both tea products. In addition, two anthocyanins namely, cyanidin-3-O-galactoside and cyanidin-3-O-glucoside were also identified. Tea catechins were also identified in the tea products derived from the purple coloured tea cultivars namely, epigallocatechin (EGC), catechin (+C), epicatechin (EC), epigallocatechin gallate (EGCG), and epicatechin gallate (ECG). Correlation between the total catechins versus the total anthocyanins and anthocyanin concentration in unaerated teas revealed significant negative correlations (r = −0.723^∗ and r = −0.743^∗∗, p ? 0.05 and p ? 0.01, respectively). However, in aerated (black) tea the correlations were insignificant (r = −0.182 and r = −0.241, p > 0.05).     

Investigation of the presence and significance of theanine in the tea plant

Theanine was determined in black teas and tea plants by a combination method of thin-layer chromatography (t.l.c.) and densitometry. It was shown that in 20 samples of black tea from different qualities and sources the amount varied from 0.33 to 1.59 g 100 g^?1 dry wt. The highest quality black teas possessed the lowest amount of theanine, but it is subject to chemical degradation during black tea manufacture. The investigation of physiological function of theanine in the tea plant showed that during germination the theanine level reached a maximum after 45 days. This indicates that at this period of the growth of the tea plant theanine acted as a source of nitrogen and as a starting point for the synthesis of the carbon skeletal compounds of the tea plant. Theanine was found to exist in all parts of the tea plant but it accumulated more in young and active tissues and also in younger plants, which emphasises its metabolic role in the tea plant. The distribution of theanine in the shoots indicated that the first leaf was the principal site for the synthesis of polyphenolic compounds from theanine.     

Simultaneous purification of tea polyphenols and caffeine from discarded green tea by macroporous adsorption resins

To separate and purify tea polyphenols and caffeine from discarded green tea crude extract with macroporous adsorption resins (MARs), the adsorption properties of twenty kinds of MARs are systematically evaluated. The results show that GS-18 has higher separation efficiency than other MARs, and the experimental data fit best to the pseudo-second-order kinetic model. And adsorption isotherms and thermodynamics of tea polyphenols and caffeine on GS-18 are investigated. The separation parameters of tea polyphenols and caffeine from discarded green tea crude extract are optimized according to dynamic adsorption/desorption experiments with the column packed with GS-18. Through only one cycle treatment, the content of tea polyphenols increases 3.0-fold from 20 to 60 % with a recovery yield of 91 % and that of caffeine increases 3.1-fold from 7 to 22 % with a recovery yield of 98 %. The results demonstrate that the method of MARs will provide useful help for the development of large-scale separation of tea polyphenols and caffeine from discarded green tea in industry.