萎凋方式对黄化英红九号红茶品质的影响

以黄化英红九号红茶为材料,研究日光萎凋和鼓风萎凋2种方式对红茶生化成分和色度值的影响,并对其相关性进行分析。结果表明:与日光萎凋方式相比,鼓风萎凋方式对茶叶水浸出物、茶多酚、咖啡碱、总黄酮、游离氨基酸和茶色素的影响较大;茶红素和茶褐素含量高。萎凋时间在10～15h的鼓风萎凋红茶茶汤色差值较大。随萎凋时间的延长,茶多酚、总黄酮和儿茶素显著降低,可溶性糖和咖啡碱变化不显著;茶汤ΔL*和ΔE*ab增加,Δa*和Δb*降低。相关性分析表明,萎凋叶含水量与总黄酮、Δa*、Δb*极显著正相关。茶黄素和茶红素对Δb*显著正向作用。茶黄素对Δa*有显著正向作用。     

川红工夫加工过程多酚类物质及其相关酶的变化规律

以四川小叶种群体品种的一芽二叶为原料,采用传统工艺制备川红工夫,检测其茶多酚、黄酮、儿茶素、茶黄素、茶红素的含量,以及多酚氧化酶和过氧化物酶活性的变化,分析多酚类化合物含量与其形成相关酶活性之间的关系。结果表明：茶多酚和儿茶素含量在加工过程中呈现下降趋势;黄酮、茶黄素和茶红素含量在揉捻阶段显著增加,黄酮和茶黄素含量在发酵过程中较揉捻时降低;多酚氧化酶和过氧化物酶活性在揉捻阶段呈较显著下降趋势。通过相关性分析发现：茶多酚含量与多酚氧化酶（polyphenoloxidase,PPO）和过氧化物酶（peroxidase,POD）活性之间存在极显著正相关;茶黄素含量与POD活性呈极显著负相关;茶红素含量与POD活性及PPO活性分别呈极显著和显著负相关。适当延长揉捻时间和减少发酵时间,或是在发酵过程中采用提高多酚形成相关酶活性的方法,可制备出高茶黄素含量的川红工夫。     

光质萎凋对不同茶树品种红茶品质的影响

本文以室内自然萎凋为对照,比较红光、黄光、蓝光的不同光强（1000、1500、2000 lx）对不同品种红茶感官品质和主要成分的影响。结果表明,与对照相比,光质萎凋能保持或提升福鼎大白茶、蜀永1号萎凋叶游离氨基酸含量,保持或提高了四川中小叶种红茶茶黄素含量;蓝光可提升蜀永1号、四川中小叶种红茶可溶性糖含量,还可降低福鼎大白茶、蜀永1号红茶茶褐素含量。黄光光强与福鼎大白茶红茶可溶性糖含量呈显著正相关,与四川中小叶种茶褐素含量存在极显著正相关,与蜀永1号萎凋叶和红茶茶多酚含量呈较大负相关,但不显著,而蓝光光强与四川中小叶种红茶可溶性糖含量呈较大正相关,但不显著。综合感官品质,福鼎大白茶红茶最佳的萎凋光质为1500 lx黄光、2000 lx黄光,茶红素含量较高,分别为2.211%、2.049%,而茶褐素含量较低,分别为3.081%、3.025%;蜀永1号红茶最佳的萎凋光质为1500 lx黄光,游离氨基酸含量最高,为2.8%;四川中小叶种红茶最佳的萎凋光质为1500 lx黄光、1500 lx蓝光,前者游离氨基酸含量较高,为3.4%,后者茶黄素含量较高,为0.280%,茶褐素含量较低,为2.937%。所以1500 lx黄光有利于提升所选品种红茶品质。     

萎凋叶含水量对四川中小叶群体种工夫红茶品质形成的影响

目的探索萎凋程度对重庆工夫红茶品质形成的影响。方法以四川中小叶群体种为研究对象,分析比较了3个萎凋含水量:处理A(69.59%)、处理B(65.17%)、处理C(59.20%)萎凋叶红茶加工过程中色泽、多酚氧化酶(polyphenylene oxide, PPO)活性变化及对后续揉捻效果、生化成分、工夫红茶成茶品质形成的影响。结果随着萎凋水分的降低,萎凋叶L*, b*值呈下降的趋势, a*值呈上升的趋势, 4～6 h时均出现了与总体趋势相反的波动;加工过程中,各处理L*,b*值均呈下降的趋势,a*值在发酵前呈增高的趋势,干燥后值减小。成茶色泽L*a*b*值则均表现为处理A处理C处理B。加工过程中PPO活性呈先升后降的趋势,随萎凋程度的加重,高峰往后延迟且活性越强,处理C在发酵环节中活性最高。揉捻环节随着萎凋叶含水量的降低成条率越高,扁条率越低,细胞破碎率越高,处理C效果最好。内含物质随着萎凋叶含水量的减少,茶多酚先增后减,氨基酸先减后增,咖啡碱呈先减后增再减式起伏变化;水浸出物、可溶性糖差异不明显;成茶中处理C综合感官品质表现最好。结论萎凋叶含水量在60%左右时,有利于发挥四川中小叶群体种品种优势,加工出的工夫红茶品质良好。     

萎凋程度对夏暑红茶滋味香气的影响

为研究不同萎凋程度对夏暑红茶滋味和香气的影响,采用萎凋槽萎凋方式并辅于晒青、摇青工艺,通过对萎凋叶含水量的监控,分别将含水量为66%、62%、58%的萎凋叶设置为轻萎凋、中萎凋和重萎凋3个不同处理,探索不同萎凋程度对红茶中茶多酚、游离氨基酸、可溶性糖、黄酮、水浸出物、茶三素、儿茶素组分等滋味物质与香气成分的影响。结果表明:在滋味上轻、中萎凋的红茶比重萎凋红茶好,随萎凋程度的加重,茶多酚、儿茶素总量表现出减少的趋势,可溶性糖与茶红素表现出增加的趋势,游离氨基酸、黄酮、咖啡碱、茶黄素均表现为中萎凋红茶中含量最高;香气上轻萎凋香气最佳且带有花香。醇类、酯类、醛类、碳水化合物是主要的香气组分,醇类与醛类、酯类、碳水化合物分别在轻萎凋、中萎凋、重萎凋红茶中含量最高。     

萎凋通氧量对鲜叶品质生化成分和酶活性动态变化规律的影响

为研究不同萎凋通氧量对鲜叶常规生化成分和酶活性动态变化规律的影响,以一芽二叶茶鲜叶为原料,设置21%O2,40%O2,59%O23个通氧量梯度,对不同含水率的萎凋叶、揉捻叶、发酵叶、足干叶等进行取样,测定茶多酚、氨基酸、黄酮、可溶性糖、咖啡碱、水浸出物及儿茶素组分等含量,多酚氧化酶和过氧化物酶的酶活性,以及足干叶的茶色素,并对成茶进行感官审评。结果表明,随着制茶过程中鲜叶含水率的逐渐下降,茶多酚、氨基酸、可溶性糖、水浸出物及儿茶素组分等含量呈现下降的趋势,黄酮和咖啡碱含量呈上升趋势;萎凋过程中鲜叶的茶多酚、氨基酸、黄酮等含量均呈前期逐渐下降,后期略有回升的趋势,可溶性糖和水浸出物含量逐渐下降,咖啡碱含量逐渐上升,多酚氧化酶活性呈下降趋势,过氧化物酶活性呈上升趋势;萎凋末期样和足干样的常规生化成分含量与萎凋通氧量呈正相关,而酯型儿茶素组分含量和儿茶素总量以40%O2处理最高,59%O2处理最低;多酚氧化酶活性以59%O2处理最低,其它两个处理无显著差异,过氧化物酶活性与萎凋通氧量呈正相关。成品茶的茶黄素组分和总量、茶红素含量以及感官审评总分均以59%O2处理最优,40%O2处理次之,21%O2处理最低。     

不同茶树品种悬浮发酵对茶黄素形成的影响

以同一嫩度的英红9号、福鼎大白、金观音、槠叶齐4 个差异性较大品种的鲜叶为原料进行悬浮发酵实验,开展茶树品种、酶源类型（多酚氧化酶（polyphenol oxidase,PPO）、过氧化物酶（peroxidase,POD）活性等）、儿茶素组分（含量、配比等）对茶黄素形成影响的研究,结果表明：PPO活性/POD活性比值以福鼎大白最高,英红9号和金观音次之;简单儿茶素总量（total simple catechin,TSC）和酯型儿茶素总量（total ester-type catechin,TETC）均以英红9号最高,福鼎大白和金观音次之,槠叶齐最低;各儿茶素组分除没食子儿茶素没食子酸酯和儿茶素没食子酸酯外均呈前期迅速下降、后期平稳的趋势,儿茶素剧烈消耗期在发酵前30?min;茶黄素组分形成量均呈先升后降的趋势,峰值点在发酵15?min和30?min,不同品种不同茶黄素组分峰值时间和高度不同;整体上,以最高儿茶素底物含量和第2高PPO活性/POD活性比值的英红9号品种茶黄素的形成量显著最多,最高PPO活性的福鼎大白和金观音品种可最快形成茶黄素,但较高活性的POD和较低含量的儿茶素,导致茶黄素的形成量较低,而具有最低PPO活性/POD活性比值和最低含量的儿茶素底物的槠叶齐品种形成茶黄素的能力最差。即PPO活性/POD活性比值越大,儿茶素底物含量越大,TETC/TSC比值越大,形成茶黄素的能力越强。     

红茶萎凋对歧化和苯骈化反应的作用及机制

红茶加工过程中儿茶素会发生歧化和苯骈化反应,萎凋期间叶片的物理和化学变化对后期儿茶素的转化具有一定作用。红茶揉捻开始,儿茶素氧化同时参与歧化反应生成聚酯型儿茶素(Theasinensins,TSs)和苯骈化反应生成茶黄素(Thea?avins,TFs),2类二聚物是儿茶素氧化的主要氧化产物,且均不稳定。通过萎凋程度和萎凋温湿度两部分实验,探究了萎凋对主要儿茶素歧化和苯骈化反应及其产物的影响与机制。研究表明:萎凋条件对2种途径有一定影响,萎凋3～12 h时,时间越长制成的红茶TFs含量越低,TSs含量越高,60%湿度和20℃萎凋处理有利于歧化反应生成TSs;EGCG含量占儿茶素总量的一半上,红茶揉捻期间EGCG氧化的歧化途径高于苯骈化途径,随着发酵时间延长,歧化途径占比逐渐降低,干燥工序中TSs含量升高,TFs含量降低。综合来看,萎凋作为红茶加工不可或缺的一部分,可通过萎凋条件调节儿茶素的歧化和苯骈化反应进程。     

不同嫩度鲜叶加工工夫红茶对品质和内含成分的影响

为研究不同嫩度鲜叶加工工夫红茶对品质和内含成分的影响,分别采摘一芽一二叶、一芽二三叶和一芽三四叶原料,按照萎凋、揉捻、发酵和干燥4道工序加工工夫红茶,探索不同嫩度鲜叶加工工夫红茶过程中茶多酚、儿茶素、茶黄素、氨基酸等含量的变化,以及对茶叶感官品质的影响。结果表明:感官品质总分表现为一芽一二叶一芽二三叶一芽三四叶,其中一芽三四叶各感官因子得分均为最差,一芽一二叶和一芽二三叶的汤色、香气和滋味内质评分相近;内含成分的变化表现为揉捻和发酵期间儿茶素含量迅速下降,水浸出物含量也有降低,茶黄素含量上升,红茶加工过程中咖啡碱含量变化不大,不同嫩度原料之间比较,红茶加工过程中EGCG的氧化率一芽一二叶最高为92.09%,一芽二三叶为85.29%,一芽三四叶为86.30%,生成的茶黄素为一芽二三叶最高,氨基酸含量为一芽一二叶一芽二三叶一芽三四叶。     

‘巴山早’紫色芽叶红茶加工工艺研究及品质评价

为了探究‘巴山早’紫色芽叶的红茶加工工艺及其制茶品质特点。本研究选用‘巴山早’紫色芽叶为原料,在万源红茶加工工艺基础上进行工艺优化,对红茶关键加工技术（萎凋、发酵和干燥）进行单因素实验和正交试验,以感官评分、茶黄素和茶红素之和与茶褐素的比值TFRB为评价指标,确定紫色芽叶红茶的最优工艺参数,探究关键加工技术不同参数对红茶品质的影响;以‘福鼎大白’绿色芽叶为对照,采一芽一叶新梢,按照优化后的加工工艺加工成红茶,所制茶样与‘巴山早’紫色芽叶红茶通过感官审评、内含品质成分测定分析和香气组分检测分析。结果表明,‘巴山早’紫色芽叶红茶的最优加工工艺为萎凋时间21 h,发酵时间4.5 h,干燥温度90±2℃,此时感官评分最高为92.83±0.19,‘巴山早’紫色芽叶红茶的感官品质优于对照,其茶多酚、氨基酸、可溶性糖、水浸出物、咖啡碱、茶黄素和茶红素含量分别为12.58%、3.62%、2.89%、37.89%、4.61%、0.38%和3.57%,均高于对照,TFRB为1.07是其滋味鲜醇,汤色红亮的物质基础;氨基酸组分总量、呈鲜爽味氨基酸组分和呈甜味氨基酸组分含量分别为32.35、22.68和3.4...     

The effect of withering on fermentation of tea leaf and development of liquor characters of black teas

Depression in polyphenol oxidase (PPO) activity during the withering of tea leaf (Camellia sinensis) in black tea manufacture affected the oxidative-condensation of tea flavanols in forming theaflavins (TF) and thearubigins (TR), which are associated with brightness, briskness and ‘body’ of tea liquors. In contrast to conventionally manufactured CTC teas, unwithered fresh leaf CTC produces a higher proportion of TF and lower TR, resulting in bright, brisk and thin liquors. Hardness of wither was accompanied by a further depression in PPO activity, and formation of TF also declined with a concomitant loss in brightness and briskness. The TR content increased up to a certain degree of wither and thereby improved the ‘body’ of the liquor. Very hard wither, accompanied by a large reduction in moisture content, restricts PPO activity. It appears that in the fresh leaf, high moisture levels together with dissolved oxygen accelerate the enzymic oxidation and produce large amounts of TF. Senescence of the leaf seems to facilitate the production of TR.     

A reliable technique to identify superior quality clones from tea germplasm

Variations in the substrate level and enzyme activity of prominent south Indian tea germplasm were studied. The content of polyphenols, catechins (substrates) and polyphenol oxidase (PPO) showed variation, which influenced the final black tea quality. The enzyme PPO occurs in tea shoots and catalyzes the reactions between catechins to form theaflavins in the presence of oxygen. The catechins mainly epicatechin (EC), epigallo catechin gallate (EGCG), epicatechin gallate (ECG) and epigallo catechin (EGC) get mixed with PPO during the oxidation process to form quality constituents like theaflavins (TF), thearubigins (TR) and high polymerized substances (HPS). Theaflavins and their fractions such as simple theaflavin, theaflavin monogallate, (TFMG), theaflavin digallate (TFDG) in black tea are the essential quality constituents that are responsible for the liquor characteristics where as TR and high polymerized substances impart colour to the liquor. As oxidation of macerated leaves proceed through different stages of tea manufacture, a decline in PPO activity, polyphenol and catechin contents were observed. Data revealed that the oxidation reaction was faster during the initial stages of oxidation. During the period, oxygen consumption was higher and declined thereafter. Ratio between the enzyme (PPO) and its substrate (catechins) were used to characterize the quality potential of tea clones. An attempt has also been made to categorize prominent tea clones as high, moderate and average quality clones based on their enzyme substrate ratio. Theaflavin content (oxidation product) of different tea clones suggests that the ratio between PPO and catechins forms an important criterion which determines black tea quality. Results obtained were compared with standard clones of known high quality (CR-6017) and moderate quality (SA-6). The study reveals that the enzyme substrate ratio can be used to identify superior quality clones from the existing tea germplasm.     

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     

不同反应条件对勐库大叶种多酚氧化酶合成茶黄素的影响

研究不同因素对勐库大叶种多酚氧化酶催化合成茶黄素的影响,结果表明在p H 4.0、37℃、茶多酚质量浓度为4.5 mg/mL的条件下,勐库大叶种多酚氧化酶催化1.0 h,最有利于茶黄素的合成,其总产量可达(461.12±15.01)μg/mL,转化率为(15.31±0.40)%。勐库大叶种多酚氧化酶对酯型儿茶素催化活性更强,催化合成酯型茶黄素为主,在催化过程中还伴随着表没食子儿茶素和没食子酸的生成,有利于茶黄素的合成积累,这可能与滇红优异品质形成有关。     

The Impact of Withering Temperature on Black Tea Quality

High leaf temperatures during the withering process of black tea manufacture decrease the theaflavins, brightness, flavour index and sensory evaluation scores of black tea. Black teas manufactured with withering temperature above 30°C have high thearubigins and total colour levels but lack briskness. Results suggest a need to control temperatures below 30°C during withering.     

Effect of withering on the polyphenol oxidase level in the tea leaf

The level of polyphenol oxidase in tea leaf (Camellia sinensis) decreased on partial desiccation of the leaf during the withering process of black tea manufacture. However, sufficient activity remained, even after withering, to oxidise the available substrate in the leaf. The loss in activity due to desiccation was restored on rehydration.     

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.     

乌龙茶加工过程中内源酶活性的变化规律

在乌龙茶加工过程中制品的内源酶活性变化呈现一定的规律性：制品的多酚氧化酶(PPO)、过氧化物酶(POD)、蛋白酶(PA)、淀粉酶(Am)、纤维素酶(CE)和果胶酶(PC)经晒青后，活性明显上升，随摇青进程，这些酶的活性呈现最大值的时间先后不一，如多酚氧化酶和纤维素酶在第一摇后出现；蛋白酶和淀粉酶却在第二摇后；而过氧化物酶和果胶酶在第三摇后达最大值尔后，活性下降。总体上均呈现低-高-低的变化规律，而且在摇青中纤维素酶和果胶酶，多酚氧化酶和过氧化物酶还呈现此消彼长的变化趋势多酚氧化酶与过氧化物酶在晒青后均出现两条新的同工酶谱带，这对乌龙茶风味的形成可能产生不可低估的影响。