不同光质对夏秋红茶萎凋叶挥发性成分的影响

目的 探讨不同光质对夏秋红茶萎凋叶挥发性成分的影响。方法 采用顶空固相微萃取-气相色谱-质法检测0 h鲜叶和黄光(YL9h)、红光(RL9h)、紫光(VL9h)、橙光(OL9h)、蓝光(BL9h)、绿光(GL9h)、自然光(CK9h)处理的萎凋叶的挥发性成分, 并基于代谢组学, 结合多元统计分析方法筛选差异性挥发性成分, 比较不同光质对夏秋红茶萎凋叶挥发性成分的影响。结果 样本共鉴定101种挥发性成分, 包括23种醇类物质、8种醛类物质、26种酯类物质、27种烯类物质、4种烷类物质、4种酮类物质和9种其他类。经9 h萎凋后, 大多数挥发性成分含量均较0 h鲜叶有显著提高, 并且YL9h、RL9h和OL9h组中挥发性成分含量相对较高。采用代谢组学方法共筛选出20种差异代谢物, 以醇类为主, 其中YL9h和RL9h萎凋叶中苯甲醇、反式-β-金合欢烯、芳樟醇及其氧化物等花香特征成分含量相对较高。结论 不同光质对夏秋红茶萎凋叶挥发性成分影响显著, 黄光和红光萎凋处理可改善夏秋红茶的香气品质。     

Relationship between process of withering and aroma characteristics of black tea

Volatile flavour components (VFC), caffeine, crude fibre, ash and total water soluble solids (TSS) were analysed in orthodox and CTC black teas manufactured from normal and hard withered leaves. With the increase of wither, VFC, TSS and caffeine were found to increase but not crude fibre. The withering process in black tea manufacture appears to control the development of terpenoids, improving flavour quality in brewed tea.     

萎凋时间对丹霞8号主要生化成分和挥发性成分的影响

以丹霞8号为试验材料,比较不同萎凋时间茶叶中生化成分和挥发性成分,探明其变化规律。结果表明:茶多酚含量在0～23h显著增加,23～32h显著降低。0～16h游离氨基酸含量显著增加,茶氨酸则显著降低;16～50h游离氨基酸和茶氨酸均显著降低。0～50h咖啡碱含量显著增加;可可碱显著降低;叶绿素a差异不显著。叶绿素b和类胡萝卜素含量在5～28h显著降低;28～50h显著增加。萜烯是5～32h萎凋叶主体挥发性成分,萜醇是0h和50h萎凋叶主体挥发性成分。主成分分析表明,0～50h萎凋叶的生化成分特征和香气轮廓呈规律变化,生化特征可分为0～16,23～28,32～50h3个阶段;香气轮廓分为0～9,16～23,26～32,50h4个阶段。16h和23h是茶叶萎凋过程中生化成分特征和香气轮廓变化的共有时间点。     

Changes undergone by free amino-acids during the manufacture of black tea

(1) An increase in total free amino-acids during the withering stage of tea manufacture was confirmed, and was found to be dependent on storage conditions which promote the onset of senescence in plucked tea shoot tips (especially desiccation). The rate of increase was positively related to temperature up to the point where the tissues were killed, after which no further changes took place. Individually, all the major amino-acids increase during withering except the most abundant amino-acid, theanine, which shows an appreciable decrease. (2) During the fermentation stage of black tea manufacture the concentrations of leucine, isoleucine, serine, glutamic acid, glutamine, threonine and phenylalanine are appreciably reduced. Other free amino-acids undergo little change in concentration. (3) During the drying stage of tea manufacture there is a small general decrease in free amino-acid concentration. (4) There is an active metabolism of free amino-acids in plucked tea shoot tips. Within 3 h of feeding glycine-¹⁴C, radioactivity could be detected in all the free amino-acids and especially in serine which contained about ten times as much ¹⁴C as did glycine after this period. Caffeine increased in concentration and in degree of labelling with time from feeding of glycine-¹⁴C which suggests that the amino-acids are the precursors of this purine compound in tea shoot tips. (5) The effect of these changes on the organoleptic properties of black tea are discussed.     

茶饮料生产中茶乳酪形成因素的探讨

对影响茶乳酪形成的各种因素如品种、萃取温度、时间、茶汤浓度、烘焙、萃取液ｐＨ等作了全面的讨论     

不同光质萎凋对金观音红茶香气组分的影响

目的研究不同光质萎凋处理对金观音红茶香气组分的影响,确定在萎凋过程中采用不同的光质处理与红茶香气组分的关系。方法采用顶空-固相微萃取技术提取金观音红茶的香气成分,使用气相色谱质谱联用法探讨在萎凋过程中通过红光、黄光以及橙光处理后金观音红茶香气成分的变化。结果实验中的4组茶叶样品共鉴别出48种香气物质,共包含9种醇类物质、11种烯烃类物质、16种烷烃类物质、9种酮酯类物质以及3种其他类物质。红光处理检测出28种挥发性物质,香气组分占提取物总量的66.62%;黄光处理检测出28种挥发性物质,香气组分占提取物总量的67.71%;橙光处理检测出24种挥发性物质,香气组分占提取物总量的64.81%。结论红光、黄光以及橙光处理能促进长叶烯、橙花叔醇及其异构体的生成。不同光质处理能影响毛茶香气组分的含量,对于β-紫罗酮的含量会有明显的提升。选用橙光处理,能提高毛茶的香气组分以及茶叶的感官品质。     

Novel insights into the effect of withering degree on Dianhong Congou black tea quality

Withering degrees (mild, appropriate and severe) have an important effect on the quality of Dianhong Congou black tea. In this study, appropriate withering (AW) promoted the conversion of catechins, yielding theaflavins (TFs) and thearubigins (TRs). This withering degree also resulted in the degradation of flavonoid glycosides, and the formation and conversion of soluble sugars and high-boiling volatile compounds. The objective colour attributes were significantly higher under AW conditions, in addition to the best sensory qualities, including umami and sweetness flavours. Moreover, nine key non-volatile compounds (TRs, theabrownins (TBs), fructose, etc.) and seven key volatile components (benzaldehyde, trans-β-Ionone, methyl salicylate, etc.) were determined. This research provides theoretical support for in-depth exploration of the formation mechanism of Dianhong Congou black tea.     

不同光质萎凋对贡眉白茶滋味品质的影响

为筛选改善贡眉白茶滋味的最优萎凋光质,采用LED精量调制光源,通过感官审评法、超高效液相色谱串联三重四级杆质谱、高效液相色谱等方法,研究无光(对照)、日光、蓝光、黄光和红光萎凋,对贡眉白茶的感官品质、主要生化成分、部分代谢物的影响.结果表明,4个光照组感官审评的滋味、香气及总得分,均比无光组高,且红光滋味得分最高.相比...     

干燥工艺对红茶品质的影响

以碧香早夏秋季一芽二叶为原料,在萎凋、揉捻、发酵等红茶加工工艺基础上,将箱式热风、锅炒、链式热风、平板式热风和微波5种干燥方式的不同组合分别应用于毛火初干与足火复干工艺中,从感官品质、滋味品质成分和香气品质成分3个方面探讨了不同干燥工艺对红茶品质的影响。结果表明,与箱式热风初干及复干工艺加工的对照茶样相比,采用120 ℃链式热风初干和120 ℃锅炒复干工艺的红茶品质较好,汤色红橙亮,香气甜香带花香,滋味较醇爽;茶黄素、茶红素、水浸出物、可溶性糖、简单儿茶素、酯型儿茶素和总儿茶素质量分数显著增加（P<0.05）,茶多酚、咖啡碱质量分数以及酯型儿茶素/总儿茶素的比值显著降低（P<0.05）;醇类香气物质相对质量分数增加9.68%,同时增加了苯甲醇（苹果香）、7-甲基-3-亚甲基-6-辛-1-醇（花香）、异香叶醇（玫瑰香）、植物醇（花香）、2,6,6-三甲基-1-环己烯-1-乙醛（木香、玫瑰香）、2-（5-甲基-5-乙烯基四氢呋喃-2-基）丙-2-基碳酸乙酯和水杨酸甲酯（薄荷香味）等香气成分,而顺-α,α-5-三甲基-5-乙烯基四氢化呋喃-2-甲醇（带樟脑气息）、辛烯醛（略带刺鼻）、壬酸（腐臭味）等不良香气成分减少。由此提示链式热风毛火初干和炒锅足火复干相结合的干燥工艺技术有利于红茶品质的提高。     

The effect of temperature on enzyme activity during the fermentation phase of black tea manufacture

Activities of both polyphenoloxidase and peroxidase enzymes declined as a function of fermentation time, the magnitude of the effect on the former being much greater. The effect of temperature on the rate of inactivation was also much greater on polyphenoloxidase.     

Fate of imidacloprid and acetamiprid residues during black tea manufacture and transfer into tea infusion

The objective of this paper is to investigate the loss/stability of neonicotinoids (imidacloprid and acetamiprid) residues during the manufacture of black tea and to study the transfer of these pesticides from made tea to its infusion. For orthodox black tea, the manufacturing process involves leaf harvesting (plucking two leaves and a bud), withering, rolling, fermentation (oxidation), and drying. Initial withering and final drying resulted in the loss of pesticide residues, but no significant reduction in residue levels resulted from the rolling and fermentation steps. The drying process resulted in a residue transfer of 64–70% and 69–74% of the initial level, whereas the brewing process resulted in a residue transfer of 37–39% and 45–49% of imidacloprid and acetamiprid, respectively, from dried tea into the infusion. The decrease in acetamiprid levels during drying was also significant (8–13%), whereas the total loss during the manufacturing process ranged from 26 to 31%. Further, brewing for longer periods (an extended brewing time) resulted in higher transfer (up to 44% for imidacloprid and 53% for acetamiprid) of pesticides to tea infusion. Further, the extent of pesticide leaching depends on its water solubility, partition coefficient, and the brewing time.     

Optimising fermentation time in black tea manufacture

A comparative study using in-line theaflavins analysis (ILTF), theaflavins of made-tea analysis (TFMT) and tasters' evaluations, to optimise fermentation during tea manufacture, was carried out. All methods obeyed a quadratic relationship with time. On average, the optimum fermentation times were 107.7, 135.3, 136.2 and 147.4 min for ILTF, TFMT, taster D and taster E, respectively. Linear relationships between different methods had good correlation coefficients but TFMT and tasters' evaluations related best. In the absence of a taster, TFMT can be used to optimise fermentation time in tea processing.     

Effects of withering on the main physical properties of withered tea leaves and the sensory quality of congou black tea

To explore the relationship between the moisture content of withered tea leaves and their physical properties (i.e., elasticity, plasticity, flexibility, and texture) during withering, texture analyzer was employed to test the elasticity and flexibility of withered tea leaves with different moisture contents. The texture was evaluated by computer vision technology. The withered tea leaves with different moisture contents were used to process congou black tea, which was then subjected to sensory evaluation. Results showed that good elasticity, optimal flexibility, and plasticity were achieved when the moisture content of the withered tea leaves of Fudingdabai comprising two leaves and one bud varied arranging from 65.51 to 61.48%. The sensory evaluation of congou black tea revealed that moderate withering was better than long-term withering and that both moderate and long-term withering were better than no withering during processing. The moisture content was significantly correlated with the flexibility and plasticity of the withered tea leaves. Fresh tea leaves undergoing moderate withering with moisture content of 65.51–61.48% to process congou black tea, good tea shape and liquor color were achieved. This study provided new evidence that the moisture content of withered tea leaves significantly affected the quality of black tea.     

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.     

萎凋方式对γ-氨基丁酸白茶香气成分的影响

目的 为探明萎凋方式对GABA白茶香气成分的影响。方法 本研究采用顶空-固相微萃取-气相色谱-质谱联用技术（headspace solid-phase mextraction-gas chromatography-mass spectrometry,HS-SPME-GC-MS）结合感官评价和香气活性值(odour activity value,OAV）比较分析自然萎凋γ-氨基丁酸（GABA）白茶（TY）和复式萎凋GABA白茶（LY）的香气成分差异。结果 TY共鉴定出39种有效香气成分,LY共鉴定出41种有效香气成分,LY浓度及OAV值显著高于TY（p<0.05,FC>2或<0.5）。TY的香气浓郁持久,带果香和兰花香,LY的香气果香馥郁,带兰花香和栀子花香,复式萎凋有利于果香积累。结论 复式萎凋较自然萎凋更有利于芳樟醇、2-庚醇、1-己烯-3-醇、3-甲基苯甲醛、月桂醛、己酸、壬酸、2-庚酮等物质的显著富集,使得GABA白茶中的果香型风味突出,花香、清香和奶油型香气更加显著,更有利于促进GABA白茶优良品质的形成。本研究结果可为开发不同香型GABA白茶产品及加工工艺创新提供理论参考。     

Optimisation of withered leaf moisture during the manufacture of black tea based upon theaflavins fractions

A study was conducted to see the effect of different moisture content of withered leaf on the activity of oxidative enzymes polyphenoloxidase (PPO) and peroxidase (PO) and on the formation of theaflavins (TFs) and thearubigins (TRs). Six commercially popular cultivars TV1, TV7, TV9, TV23, TV26 and T.3E/3 of Assam, India, were processed in four different moisture levels (72%, 70%, 68% and 65%). Significant reduction in PPO and PO enzymes, TFs, TRs and theaflavin digallate equivalent was observed with the decrease in moisture content of withered leaf. The TFs (0.83–5.4 mg g^?1) and TRs (23–107 mg g^?1) fractions were lowest at moisture level 65 ± 1%. Of the six cultivars studied, better quality of black tea was obtained for cultivar TV1, TV9 and TV23 at 70 ± 1% moisture content, while for TV7 and TV26, it was 68 ± 1%. Withered leaf moisture content should be carefully chosen to obtain the better quality tea from specific cultivar.     

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。     

红茶萎凋处理温湿度条件对PPO、POD及茶多酚和色素的影响

通过控制不同温湿度进行萎凋,然后在较理想的揉捻、发酵、干燥条件下制成红茶。检测加工期间多酚氧化酶(PPO)、过氧化物酶(POD)活性以及茶多酚、茶色素含量。研究表明:不同温湿度处理萎凋期间PPO活性与萎凋叶含水量呈显著的正相关,相对湿度(RH)70%萎凋制得的红茶茶黄素含量最高,红茶发酵过程中茶多酚的氧化形成茶色素类与PPO、POD活性关系紧密,并且萎凋叶POD活性与成品茶茶黄素和茶红素含量呈极显著的负相关。      

Some studies on carotenoids and their degradation in black tea manufacture

The four major carotenoids, β-carotene, lutein, violaxanthine and neoxanthine were estimated spectroscopically in four different Tocklai Experimental Station released tea clones, namely, TV-1 (China hybrid), TV-2 (Assam(Betjan) variety), TV-9 (Assam-Cambod variety) and TV-17 (China hybrid). The quantitative changes of these carotenoids in different stages of black-tea manufacture were also studied in TV-2 (less flavoury) and TV-17 (flavoury) clones against TV-1 as standard. Comparative study showed that TV-2 contained the least amount of these carotenoids where as TV-9 and TV-17 contained greater amounts. All these carotenoids were found to decrease appreciably during black-tea manufacture. The decrease was found to be higher in the curling, tearing, crushing method than in the conventional orthodox method of tea manufacture. The changes of two of these carotenoids viz. β-carotene and lutein were not significant statistically during withering but were highly significant during fermentation. However, the reverse was true for violaxanthine where as the neoxanthine shows significant changes in both of these stages. The vitamin-A value was calculated from the residual β-carotene amount, pro-vitamin A, in black tea.     

正山小种红茶挥发性成分分析

采用顶空固相微萃取结合气相色谱-质谱联用对不同价位的正山小种红茶的挥发性成分进行了分析。结果表明,不同价位正山小种红茶主要挥发性成分都包括醇类、醛类、碳氢类、酯类、酚类、酮类、酸类、含氮类以及杂氧类化合物,但各类化合物在不同红茶中的相对含量存在差异。红茶A（高价位）中苯乙醇（11.05%）,苯甲醇（7.88%）,香叶醇（5.75%）,苯甲醛（5.33%）,水杨酸甲酯（3.74%）和（E,E）-3,5-辛二烯-2-酮（3.42%）等成分相对含量较高。红茶B（中等价位）中香叶醇（7.4%）,愈创木酚（5.83%）,苯酚（4.21%）,2-吡咯甲醛（3.63%）,萘（3.53%）和水杨酸甲酯（3.51%）等成分相对含量较高。红茶C（低价位）中香叶醇（7.98%）,苯乙醇（7.32%）,苯甲醛（7.13%）,苯甲醇（3.33%）,水杨酸甲酯（3.24%）,糠醛（2.52%）等成分相对含量较高。