不同时期正安白茶呈味物质变化及滋味评价

为更好地开发和利用正安白茶资源。以不同时期白叶1号茶树的茶青(1芽1叶)制成的松针形正安白茶为原料,采用化学分析和量化感官分析方法,根据主要呈味物质、儿茶素组分及茶汤滋味分属性(醇度、浓度、厚度、鲜度、涩度)的变化特点,建立呈味物质和滋味分属性之间的相关性,为正安白茶产品风味研究和品质提升提供理论基础。结果表明:不同时期正安白茶中茶氨酸、游离氨基酸以白化期为转折点先增后降;茶多酚呈现逐渐增加的变化趋势;酚氨比以白化期为转折点先降后增;咖啡碱变化不显著;表没食子儿茶素(EGC)、儿茶素(C)、表儿茶素(EC)、非酯性儿茶素先升后降,以复绿初期最高,白化期最低;表没食子儿茶素没食子酸酯(EGCG)、表儿茶素没食子酸酯(ECG)、没食子儿茶素没食子酸酯(GCG)、酯性儿茶素呈持续升高变化,以复绿后期最高,白化期最低;儿茶素呈先降后升变化,以白化期最低,复绿后期最高;浓度、厚度和涩度呈先降后升变化,以白化期最低,复绿后期最高;醇度、鲜度呈先升后降变化,以白化期最高。茶多酚、酚氨比、EC、EGCG、ECG、GCG、儿茶素类总量和酯性儿茶素是正安白茶茶汤滋味浓度、厚度和涩度的主要贡献物质,游离氨基酸总量、茶氨酸是茶汤滋味鲜度和醇度的主要贡献物质。     

日照红茶初制过程主要生化成分变化的研究

研究了日照红茶初制过程主要生化成分如茶多酚、儿茶素总量、游离氨基酸、咖啡碱,以及儿茶素类组分(EGC、C、EC、EGCG、ECG)、水溶性茶色素(茶黄素、茶红素、茶褐素)含量的变化。结果表明,茶多酚、儿茶素总量呈明显的下降;游离氨基酸、咖啡碱含量在整个初制过程中总体呈现下降趋势;儿茶素类组分以酯型儿茶素EGCG、ECG变化尤为剧烈,在揉捻工序已经完全转化消失;水溶性茶色素TF、TR和TB含量呈现上升的趋势,毛茶的TR/TF比值为10.27。此外,文章还对日照红茶与南方红茶的主要生化成分进行了比较分析,以研究北方茶叶制成红茶的特点。     

不同种类茶叶多酚及生物碱含量特点分析

选取市售29种不同类别茶叶,分别测定其总多酚、儿茶素及组分,茶黄素总量、没食子酸、总黄酮等多酚成分,以及咖啡碱、茶碱、可可碱等生物碱成分,并总结各类茶叶成分特点。研究发现,绿茶和普洱生茶具有较高的茶多酚和儿茶素含量,但绿茶的儿茶素单体以EGCG为主,而普洱生茶EGC、ECG、EGCG 3种单体含量相近;乌龙茶咖啡碱含量明显低于其他种类茶叶;红茶、普洱熟茶的儿茶素总量占茶多酚比例显著低于其他茶类,但红茶的茶黄素含量较高,普洱熟茶具有较高的没食子酸含量。     

贮藏时间对雅安藏茶中活性成分及其抗氧化活性的影响

为研究贮藏过程中雅安藏茶中茶色素、多酚及其抗氧化活性的变化情况,对不同贮藏时间藏茶中茶色素、总多酚、总黄酮及其抗氧化活性进行比较。结果表明,随着贮藏时间从4年递增到10年的过程中,藏茶中茶褐素含量从5.95 g/100 g显著提升到8.54 g/100 g（P<0.05）,而茶黄素、茶红素、总多酚、总黄酮、咖啡碱、儿茶素以及儿茶素单体（EGC、CG、ECG、EGCG、EC）含量显著降低（P<0.05）。此外,藏茶ABTS自由基清除能力从6759.54 μg/g显著减弱到4086.43 μg/g（P<0.05）,而DPPH自由基清除能力同样从43.50 μg/g显著减弱到 21.02 μg/g（P<0.05）,且与总多酚、总黄酮、儿茶素、咖啡碱、EGC、EC、EGCG、ECG、茶红素、茶黄素呈显著正相关（P<0.05）。而茶褐素与总多酚、总黄酮、儿茶素、咖啡碱、CG、EGC、EC、EGCG、ECG、茶黄素以及茶红素呈现显著负相关（P<0.05）。贮藏时间越长,藏茶中多酚类物质降低而茶褐素含量越高,使得陈化藏茶具有降脂减肥等保健功效。     

不同闷黄工艺对蒙顶黄芽风味品质的影响

为缩短传统蒙顶黄芽加工时间,提出一种快速闷黄工艺,并结合感官审评、高效液相色谱(high performance liquid chromatography,HPLC)、气相色谱-质谱(gas chromatography-mass spectrometry,GC-MS)等分析方法,探讨不闷黄、传统闷黄、快速闷黄工艺对蒙顶黄芽风味品质的影响。结果表明,2种闷黄工艺的感官审评总分均比不闷黄工艺高,且快速闷黄工艺总分最高。闷黄工艺后,表没食子儿茶素(epigallocatechin,EGC)、儿茶素(catechin,C)、表儿茶素(epicatechin,EC)、咖啡碱、可溶性糖和谷氨酸含量均增加,EGC、可溶性糖和谷氨酸含量增加均达到显著水平(P<0.05);表没食子儿茶素没食子酸酯(epigallocatechin gallate,EGCG)、表儿茶素没食子酸酯(epicatechin gallate,ECG)、儿茶素总量均减少,快速闷黄工艺的EGCG、茶多酚、氨基酸总量、茶氨酸、叶绿素b和叶绿素总量的减少均达到显著水平(P<0.05)。3种工艺样品均鉴定出42种香气成分...     

工夫红茶咖啡碱和5种儿茶素组分近红外快速测定方法的研究

提出一种利用近红外光谱技术无损快速检测工夫红茶咖啡碱(Caffeine)和5种儿茶素(儿茶素(Catechin,C)、表儿茶素(Epicatechin,EC)、表没食子儿茶素(Epigallocatechin,EGC)、表儿茶素没食子酸酯(Epicatechin gallate,ECG)、表没食子儿茶素没食子酸酯(Epigallocatechin gallate,EGCG))组分含量的新方法。实验样品共计240个,手动选择180个样品作为校正级,剩余60个样品作为预测集;利用OPUS7.0软件优化出各模型最佳波数段和最佳预处理方法,平滑点数17,维数1,结合咖啡碱(Caffeine)和5种儿茶素组分C、EC、ECG、EGC、EGCG含量建立预测模型,分析预测模型的预测性能。结果表明:各预测模型预测精准度高,均可用于咖啡碱和5种儿茶素组分C、EC、ECG、EGC、EGCG检测。其中,各模型校正相关系数(Rc)为91.85%~99.49%,校正均方根误差(RMSEC)为0.0187~0.353;预测相关系数(Rp)为97.12%~99.88%,预测均方根误差(RMSEP)为0.00759~0.0773。各模型校正集和预测集均有较高的拟合度,模型预测性能咖啡碱EGCECECGEGCGC。结论:近红外光谱图结合咖啡碱(Caffeine)和5种儿茶素组分C、EC、ECG、EGC、EGCG含量建立的各预测模型预测性能优,可用于工夫红茶咖啡碱(Caffeine)和5种儿茶素组分C、EC、ECG、EGC、EGCG含量快速无损检测。     

酯型儿茶素的热稳定性及其上染蚕丝效果

为阐明酯型儿茶素的氧化聚合作用及其对蚕丝染色效果的影响,采用超高效液相色谱串联四极杆飞行时间质谱分析了表没食子儿茶素没食子酸酯（EGCG）、没食子儿茶素没食子酸酯（GCG）和表儿茶素没食子酸酯（ECG）等儿茶素染液的热稳定性。结果表明：儿茶素受热不稳定,转化程度也有差异;单一成分时,ECG的转化率最高,GCG的最低;多种成分共存时,GCG和ECG的协同效应较强,转化率相近。研究EGCG、GCG和ECG在蚕丝上的着色效果发现：EGCG、GCG 和ECG等比例染色时,蚕丝对酯型儿茶素的吸附率为ECG＞GCG＞EGCG;不同比例混染时,蚕丝对酯型儿茶素的吸附率相近,EGCG与GCG的着色能力较ECG强。可见ECG的热稳定性不会影响蚕丝的吸附率,且其着色程度较浅,因而更适于用作植物染色剂。     

薄层层析后生物显影检测茶多酚组分的抑菌效果

用薄板在异丁醇 :醋酸 :水 ( 4:1:5 )的展开体系中层析分离茶多酚 ,得到茶多酚组分的四个色点 ,即茶多酚的主要成分EGCG、ECG、ECG、EC ,根据各组分的Rf值和标准品作对照 ,鉴定各色点对应的茶多酚组分 ;将完成分离的薄板覆盖于加有溴甲酚紫指示剂的大肠杆菌培养基上培养 ,观察到抑菌圈出现 ,其抑菌圈大小为EGCG >ECG >EGC >EC。     

绿茶多酚化合物的精制和抗氧化试验

应用高压液相色谱法和葡聚糖凝胶柱层析技术 ,从绿茶多酚化合物中分离纯化精制EGCG(表没食子儿茶素没食子酸酯 ) ,EGC(表没食子儿茶素 )和ECG(表儿茶素没食子酸酯 )等单体化合物 ,并用油脂氧化稳定测定仪 (Rancimat)对其抗氧化性能进行了试验。结果表明 ,抗氧化性能依次排列为 :EGCG >EGC >ECG >BHT(BHT为商品油脂抗氧化剂 )     

热加工处理对奶茶体系中茶多酚生物可及性的影响

实验采用体外模拟胃肠消化方法,结合高效液相色谱检测,探究热处理加工条件(80℃/20 min、100℃/5 min)和加热方式(蛋白与茶多酚混合加热、蛋白单独加热)对奶茶模拟体系中表没食子儿茶素没食子酸酯(epigallocatechin gallate,EGCG)、表没食子儿茶素(epigallocatechin,EGC)、表儿茶素没食子酸酯(epicatechin gallate,ECG)及表儿茶素(epicatechin,EC)生物可及性的影响。结果表明,消化前加入乳清蛋白会降低游离茶多酚的含量,其中EC降低12.76%最明显;乳清蛋白的单独加热处理更能降低游离茶多酚的含量,其中蛋白在100℃加热下游离茶多酚含量最少;80℃热处理体系消化前游离多酚含量均大于100℃热处理体系。热加工处理对奶茶体系中茶多酚的生物可及性存在不同程度的影响——除80℃蛋白单独加热外,其余热处理均降低EGCG的生物可及性,降低11.11%~18.38%;100℃蛋白混合加热有利于提高EGC的生物可及性,提高9.05%,且除80℃混合加热外,其余热处理方式可显著降低其生物可及性,降低24.86%~40.14%;100℃热处理方式可显著提高ECG的生物可及性,提高22.72%~28.05%;80℃加热条件可提高EC约7.24%的生物可及性,而100℃热处理方式可降低EC约47.14%的生物可及性。相同热处理下,添加乳清蛋白可提高儿茶素的生物可及性(除EGC 80℃蛋白单独加热组外)。     

乌龙茶加工过程中儿茶素的稳定性及化学变化

研究半发酵乌龙茶加工对活性化学成分儿茶素的影响。采摘的鲜叶立即在严格控制的加工条件下进行加工,分析每道加工工艺操作所制茶叶的儿茶素总量和各种儿茶素单体(－)-儿茶素、(－)-表没食子儿茶素、(＋)-儿茶素、(－)-表儿茶素、(－)-表没食子儿茶素没食子酸酯、没食子儿茶素没食子酸酯、(－)-表儿茶素没食子酸酯、(－)-儿茶素没食子酸酯的含量。研究表明,在乌龙茶加工过程中,儿茶素总含量略有下降,约为10%;儿茶素单体变化不一。在加工工艺中,做青、杀青和干燥对儿茶素含量影响较大。为使乌龙茶中儿茶素的潜在健康效益最大化,这3 道工艺应在茶叶生产中加以考虑并做到最优化,以期为乌龙茶加工研究提供一定的参考依据。     

Correlation between leaf age,shade levels,and characteristic beneficial natural constituents of tea (Camellia sinensis) grown in Hawaii

This study showed the relationship between tea leaf age, bud and first two leaves, and shade levels, on the relative concentrations of six major compounds of tea leaf, namely l-theanine, caffeine, and the major tea catechins; (−)-epigallocatechin gallate (EGCG), (−)-epigallocatechin (EGC), (−)-epicatechin (EC), and (−)-epicatechin gallate (ECG), all of which are reported to have positive effects on human health, as well as at the ferric reducing antioxidant power of bud and leaf extracts. The concentration of l-theanine and caffeine decreased as leaf age increased moving from bud to first and then second leaf, while the concentration of the four catechins increased from the bud to first and second leaves. In most cases this increase was generally relatively small but in the case of EGC it was 7 to 10-fold. Certain chemical components of freshly picked, minimally processed and essentially unoxidised tea may potentially be used as markers for age, quality, authenticity and area of growth.     

Stability of Green Tea Catechins in Commercial Tea Leaves during Storage for 6 Months

ABSTRACT:  To help meet the needs of consumers, producers of dietary tea products, and researchers for information on health-promoting tea ingredients, we determined by HPLC 7 catechins [(−)-epigallocatechin (EGC), (−)-catechin (C), (+)-epicatechin (EC), (−)-epigallocatechin 3-gallate (EGCG), (−)-gallocatechin 3-gallate (GCG), (−)-epicatechin 3-gallate (ECG), and (−)-catechin 3-gallate (CG)] in samples of 8 commercial green tea leaves of unknown history sold as tea bags in the United States, Korea, and Japan. The samples were stored at 20 °C and sampled at 1 wk and 1, 2, 4, and 6 mo. The following ranges in the initial values (0 controls) were observed (in mg/g tea leaves): EGC and C, 0 to trace amounts; EC, 1.9 to 21.1; EGCG, 13.3 to 113.0; GCG, 0.2 to 1.6; ECG, 5.7 to 50.5; CG 0.5 to 3.7; total catechins 36.5 to 169.7. Statistical analysis of the results and plots of changes in individual and total catechin levels as a function of storage time indicate a progressive decrease in the content in the total levels, most of which is due to losses in the most abundant catechins, EGCG and ECG. Possible mechanisms of degradations of catechins during storage and the possible significance of the results to consumers of tea are discussed.     

渥堆发酵过程中藏茶化学成分的变化

目的：阐明藏茶渥堆过程主要化学成分的变化规律。方法：以不同发酵阶段藏茶样为原料,研究发酵过程中藏茶水提物中可溶性固形物、可溶性糖、总多酚、总黄酮含量及水提物体外抗氧化活性的变化,并应用超高效液相色谱仪检测水提物中茶碱、咖啡碱、没食子酸和8种儿茶素类单体的含量,应用酶联免疫法测定水提物中茶黄素、茶红素和茶褐素的含量。结果：藏茶发酵过程中可溶性固形物含量先降低后略有回升,可溶性糖、总多酚、总黄酮含量逐渐降低,抗氧化活性逐渐减弱,咖啡碱呈波动状态且变化较小,没食子酸与儿茶素含量先上升再略有下降,没食子儿茶素没食子酸酯与表儿茶素含量先升高后降低,没食子儿茶素、表没食子儿茶素、表儿茶素没食子酸酯和表没食子儿茶素没食子酸酯含量均呈持续下降的状态,其中表没食子儿茶素没食子酸酯在黑毛茶中含量为39.69 mg/g,在成品茶中降至1.36 mg/g;茶红素含量先增加后降低,茶黄素含量变化很小,茶褐素含量逐渐升高（黑毛茶中3.12 g/100 g,成品茶中7.46 g/100 g）。结论：藏茶渥堆发酵过程中,可溶性糖、总多酚、总黄酮等含量降低,抗氧化活性减弱,茶碱、咖啡碱、儿茶素类单体等活性成分含量的变化趋势不一致,茶褐色含量逐渐升高。     

Cream formation and main chemical components of green tea infusions processed from different parts of new shoots

The formation of green tea cream and its chemical components were investigated. The green tea infusions were processed from different parts of new shoots: the bud and the first leaf, the second leaf and its implicative stem, the third leaf and its implicative stem, and the fourth leaf and its implicative stem, which were named as first part, second part, third part and fourth part, respectively. The results showed that the formation of tea cream and its settlement slowed down gradually from the first part to the fourth part, and that the amount of tea cream also decreased accordingly. The amount of tea cream was influenced remarkably by the chemical components in the green tea infusion. The main components of green tea cream were polyphenols (29.86 –78.66%), total sugar (14.47–27.62%) and caffeine (2.35–10.43%). Catechins (12.8–42.5%) were the main components of polyphenols which participated in tea cream formation. The main components in the catechins were found to be (−)-epigallocatechin (EGC), (−)-epigallocatechin gallate (EGCG), (−)-epicatechin (EC) and (−)-epicatechin gallate (ECG). Seven minerals were found in the tea cream, including Ca²⁺, K⁺, Mg²⁺, Mn²⁺, Na⁺, Zn²⁺ and Ni²⁺.     

Changes in content of organic acids and tea polyphenols during kombucha tea fermentation

Kombucha tea is a fermented tea beverage produced by fermenting sugared black tea with tea fungus (kombucha). Tea polyphenols which includes (-)-epicatechin (EC), (-)-epicatechin gallate (ECG), (-)-epigallocatechin (EGC), (-)-epigallocatechin gallate (EGCG) and theaflavin (TF) have been reported to possess various biological activities. The present study focused on changes in content of organic acid and tea polyphenols in kombucha tea prepared from green tea (GTK), black tea (BTK) and tea manufacture waste (TWK) during fermentation. Concentration of acetic acid has reached maximum up to 9.5 g/l in GTK on 15th day and glucuronic acid concentration was reached maximum upto 2.3 g/l in BTK on 12th day of fermentation. Very less concentration of lactic acid was observed during the fermentation period and citric acid was detected only on 3rd day of fermentation in GTK and BTK but not in TWK. When compared to BTK and TWK very less degradation of EGCG (18%) and ECG (23%) was observed in GTK. TF and thearubigen (TR) were relatively stable when compared to epicatechin isomers. The biodegradation of tea catechins, TF and TR during kombucha fermentation might be due to some unknown enzymes excreted by yeasts and bacteria in kombucha culture.     

Comparison of catechins and purine alkaloids in albino and normal green tea cultivars (Camellia sinensis L.) by HPLC

The variations in the contents of catechins and purine alkaloids in relation to the chlorophyll contents in albino tea cultivar ‘Anji baicha’ and normal cultivar ‘Longjing 43’, grown in Anji and Guilin, were determined. The results showed that, compared to ‘Anji baicha’, ‘Longjing 43’ had significantly higher (?)-epigallocatechin (EGC), (?)-epicatechin (EC), (?)-epicatechin gallate (ECG), theobromine and caffeine contents in Anji, and significantly higher (+)-catechin (C), ECG and caffeine contents in Guilin. ‘Anji baicha’ only had C content significantly higher than ‘Longjing 43’ in Anji. Correlation analysis indicated that C, EGC and (?)-epigallocatechin gallate (EGCG) were significantly and negatively correlated with chlorophyll contents, suggesting that chlorophylls might play vital roles in the regulation of catechin biosynthesis. Moreover, no significant correlation was observed between purine alkaloids and chlorophylls, indicating that the biosynthesis of purine alkaloids might be affected by genotypic factors other than chlorophyll biosynthesis.     

The development of a suitable manufacturing process for ‘Benifuuki’ green tea beverage with anti‐allergic effects

Epigallocatechin‐3‐O‐(3‐O‐methyl) gallate (EGCG3″Me) has been reported to inhibit type I allergy better than epigallocatechin gallate (EGCG), a major catechin in tea leaves (Camellia sinensis L). We examined the effects of extraction and sterilization on the catechin content and histamine release from mast cells, as a representative reaction of early phase allergy, in the manufacture of ‘Benifuuki’ green tea beverage. Among various varieties of tea, the cultivar ‘Benifuuki’ contains approximately 2% of EGCG3″Me. Ester‐type catechins and their epimers increased with the increased extraction temperature of the tea. A tea infusion, extracted at 90 °C, strongly inhibited histamine release from mast cells. Furthermore, sterilization affected the catechin content in the manufactured green tea beverage. Sterilization at high temperature promoted the isomerization of catechins and the sterilized green tea beverage had a strong inhibitory effect. When EGCG3″Me, EGCG, epicatechin‐3‐O‐gallate (ECG) and their epimers, GCG3″Me (gallocatechin‐3‐O‐(3‐O‐methyl) gallate), GCG (gallocatechin‐3‐O‐gallate) and CG (catechin‐3‐O‐gallate) were compared, the anti‐allergic effect of GCG3″Me was strongest, and the order of activity was GCG3″Me > EGCG3″Me > GCG > EGCG. We consequently suggest that it was necessary to extract components from tea at the highest temperature possible, and to pasteurize under retort conditions (118.1 °C, 20 min), to manufacture functional green tea beverage with an anti‐allergic action. Copyright © 2005 Society of Chemical Industry     

不同采制季节信阳白茶品质成分的比较分析

该研究采用高效液相色谱法（HPLC）等方法对春季、夏季和秋季茶树鲜叶加工而成的18款信阳白茶茶样中的8种儿茶素、6种黄酮类、2种酚酸、3种嘌呤碱等品质成分进行测定,对不同采制季节的信阳白茶进行品质成分进行对比分析。主成分分析（PCA）和聚类分析（HCA）技术均能将信阳白茶茶样按照采制季节不同进行归类,分为春季、夏季和秋季白茶。通过独立样本t-检验和单因素方差分析,探究了不同采制季节信阳白茶中儿茶素、黄酮类、嘌呤碱等品质成分差异。结果显示：不同采制季节信阳白茶中的品质成分均存在显著性（p<0.01）或极显著性（p<0.001）差异;春季白茶中(-)-表没食子酸儿茶素（EGC）、(-)-表没食子儿茶素没食子酸酯（EGCG）和鞣花酸含量极显著性（p<0.001）高于夏季或秋季白茶,含量分别为33.26、59.30、2.81 mg/g左右;夏季白茶中(-)-儿茶素没食子酸酯（CG）、(-)-没食子儿茶素没食子酸酯（GCG）、花旗松素、芦丁、杨梅素、山奈酚、槲皮素、木犀草素含量极显著性（p<0.001）高于秋季白茶,含量分别高达0.72、4.40、0.84、2.40、0.97、0.21、0.25、0.11 mg/g;秋季白茶中(+)-儿茶素（C）、(-)-表儿茶素（EC）、(-)-表儿茶素没食子酸酯（ECG）、没食子酸、咖啡碱和可可碱极显著性（p<0.001）高于夏季或春季白茶,含量分别为4.98、14.35、27.02、10.10、36.85、1.53 mg/g。该研究揭示了信阳白茶的品质特征和不同采制季节信阳白茶品质成分差异,为白茶等茶叶采制季节的识别提供了科学依据。     

Antiviral activity of green tea catechins against feline calicivirus as a surrogate for norovirus

In this study, several medicinal plant extracts including spices, herb teas, and medical herbs were screened for antiviral activity against feline calicivirus (FCV), a surrogate of norovirus. Among them, a methanolic extract of green tea, Camellia sinensis, only exhibited a significant antiviral activity against FCV. The methanolic extract was further fractionated with several solvents such as methanol (MeOH), n-hexane, chloroform (CHCl₃), ethyl acetate (EtOAc), n-butanol (n-BuOH), and water. EtOAc-soluble fraction exhibited the highest antiviral activity against FCV. Moreover, the analysis of the most active fraction using a HPLC led to the identification of 4 known catechins: (-)-epigallocatechin (EGC), (-)-epicatechin (EC), (-)-epigallocatechin gallate (EGCG), and (-)-epicatechin gallate (ECG). Among the catechins tested in this study, EGCG exhibited the most effective antiviral activity (EC₅₀, 12 mg/mL) with relatively low cytotoxicity (CC₅₀, 320 mg/ mL), resulting relatively high selectivity index value 26.67. To our knowledge, this is the first experimental verification showing antiviral activity of catechins from green tea against FCV.