Influence of extraction conditions on polyphenols content and cream constituents in black tea extracts

Increase in water‐to‐tea ratio and extraction time increased polyphenols recovery as well as extractable‐solids‐yield (ESY) in black tea extracts. Polyphenols content‐in‐extracted solids (PES) used as a tea quality parameter, was significantly higher at 50:1 water‐to‐tea ratio and favourably improved only up to 60 min. Extending the extraction period beyond 40 min degraded theaflavins (TF) and also affected the recovery of major catechins. Although tea cream content showed a decrease with increase in water‐to‐tea ratio, the content was nearly the same (1.80–1.89%) in all these extracts when measured at a uniform 0.5% solids concentration. The extraction conditions displayed a similar influence on the other tea cream components, namely, caffeine, calcium, pectin and protein. The conditions optimised (50:1 water‐to‐tea ratio and 40 min) based on higher PES and TF/TR ratio gave a maximum PES of 0.566 g g^?1 and TF of 0.46% (black tea) in the extract.     

Molecular evidence for maternal inheritance of the chloroplast genome in tea,Camellia sinensis (L.) O. Kuntze

BACKGROUND: Tea is the most consumed beverage worldwide after water. Yet very little is known about the genetics of tea in comparison with other crop species. Here we have taken advantage of the polymorphic nature of microsatellite DNA to investigate the mode of chloroplast inheritance in tea, Camellia sinensis (L.) O. Kuntze. This is important for the correct interpretation of phylogeny and introgression data as well as assessing the suitability of chloroplast transformation as a means for transgene containment in tea. RESULTS: The study was based on six Japanese tea cultivars, namely Aj2, CK23, Hatsumomiji, Nka05, Yamanoibuki and Kanayamidori used to generate four informative families. The parental pairs in the crosses differed at a single chlroroplast locus with respect to an imperfect microsatellite repeat of 16 nucleotide bases. In agreement with earlier cytological studies, all 61 progeny displayed a cpDNA profile that was consistent with the maternal inheritance of chloroplasts in tea. CONCLUSIONS: The data generated here provide the first molecular evidence of the plastid inheritance in tea. However, we suggest that additional families and polymorphic markers be screened for increasing the confidence in the observed maternal inheritance of chloroplasts in this important crop species. Copyright © 2011 Society of Chemical Industry     

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     

Seasonal and clonal variations in some major glycosidic bound volatiles in Kangra tea (Camellia sinensis (L.) O. Kuntze)

Seasonal and clonal variations in glycosidic bound volatile compounds were studied in tea clones representing the three different varieties viz. sinensis, assamica and cambodiensis grown in Kangra region. Glycosidic bound volatile compounds were characterised by GC–MS and quantification of major volatiles was done by GC. (E)-2-hexenal, benzyl alcohol, phenylethanol, linalool, linalool oxides, geraniol and methyl salicylate were the major glycosidic bound volatiles identified in tea shoot. Clonal variations in the quantity were observed in these bound volatiles. Seasonal variations were also observed in the quantity of bound volatiles in regional Kangra clone during three different growth flushes of tea. These variations in glycosidic precursors of volatile compounds were studied in context with orthodox made tea and its quality. These seasonal and clonal variations in precursors of volatile compounds can be directly correlated to the difference in the quality of tea made from these cultivars.     

Seasonal Variations in Quality of Kangra Tea ( Camellia sinensis(L) O Kuntze) in Himachal Pradesh

Periodic seasonal variations in infusion quality of orthodox Kangra tea over various growth flushes are reported. Theaflavins, thearubigins and caffeine recorded maximum content during early flush and gradual decline with progress in season, showing a minimum during main flush and slight improvement through backend flush. Flavour profile analysis also revealed qualitative and quantitative seasonal variations in aroma complex. High proportions of provisionally identified flavour components, linalool, geraniol, β-ionone, methyl salicylate, phenyl acetaldehyde, trans -2-hexenal, and several unidentified components with typical Kangra notes recorded during early flush exhibited comparatively lower contents or even total loss through main flush. Flavour quality also registered slight improvement in backend flush over main flush. Results suggest increasing crop productivity during early and backend flushes could enhance profitability.     

Occurrence and distribution of lipoxygenase in Camellia sinensis (L) O Kuntze and their changes during CTC black tea manufacture under southern Indian conditions

The optimal activity of tea lipoxygenase was found to be at pH 7·5 and 9·0, indicating the presence of two types of isoenzymes. Tea lipoxygenase was inhibited by cyanide and a small fraction appeared to be quite heat stable. Clonal and seasonal variations in lipoxygenase activity was significant. An increase in lipoxygenase activity was observed with leaf maturity. The lipoxygenase activity decreases with age from pruning and increases with an increase in plucking interval. The changes of lipoxygenase activity during CTC manufacture revealed that it increased with the degree of withering and upon rolling. However, a gradual decline was recorded during the fermentation and drying processes. The residual lipoxygenase activity in black tea is expected to affect its quality on storage. © 1998 Society of Chemical Industry.     

Effect of Maofeng tea processing on leaf trichomes of tea (Camellia sinensis L)

Scanning electron microscopy was used to investigate the ultrastructure of trichomes on Maofeng, a special Chinese green tea. The trichomes were cylindrical in appearance with a length of 0.6–1 mm, wall thickness of 0.2–0.3 μm and a mid-point diameter of 9–10 μm. The angles between the trichomes and the leaf under-surface were below 30° in Maofeng tea though they were 45–75° in fresh green leaf. The trichome wall consisted mainly of fibre and its outer-surface was unevenly covered with waxy substances and striped. The trichome joint, by which the trichome was attached to the leaf tower epidermis, was expanded and filled with essential oil droplets. The undeveloped trichomes assumed a flattened form because of the action of pressing during rolling and shrank during the tea drying process. During the Maofeng tea processing, trichome shedding was caused by disruption of its expanded joint structure and breakdown at the cylindrical wall above the expanded joint.     

茶黄素和咖啡碱浓度对茶乳酪形成的影响

以茶黄素和咖啡碱的相互作用来模拟茶乳酪的形成体系,通过分析其透光率、沉淀量、茶黄素和咖啡碱质量浓度的变化,研究茶黄素和咖啡碱对茶乳酪形成的影响。结果表明:随茶黄素和咖啡碱质量浓度的增加,其聚合后原溶液和贮藏液的透光率降低,贮藏液的沉淀量增加;并且当固定茶黄素和咖啡碱二者中任一物质的质量浓度,随另外一个物质质量浓度的增加,上述变化趋势显著。灭菌不影响整体的变化趋势,除此之外通过高效液相色谱分析咖啡碱和茶黄素各单体质量浓度的变化发现,咖啡碱和茶黄素-3,3’-没食子酸酯是影响模拟体系中茶乳酪形成的关键因子。基于减少茶乳酪生成,提高红茶饮料的感官效果,并同时尽可能多地保留茶黄素质量浓度,应当选择茶黄素质量浓度低于100mg/L、咖啡碱质量浓度低于200mg/L的红茶原料来制作红茶饮料。      

Isolation and chemical characterisation of a polysaccharide from green tea (Camellia sinensis L.)

BACKGROUND: To contribute towards understanding the relationship of structure and bioactivity, a protein‐bound acidic polysaccharide named TPC3‐1 was isolated and purified from low‐grade green tea (Camellia sinensis L.). The homogeneity and weight average molecular weight of TPC3‐1 was determined by agarose gel electrophoresis and high‐performance gel permeation chromatography. The monosaccharide and amino acid composition of TPC3‐1 were analysed by gas chromatography and an amino acid analyser. The molecular structure of TPC3‐1 was characterised by Fourier transform infrared spectroscopy, ¹³C nuclear magnetic resonance spectroscopy and atomic force microscopy. RESULTS: Based on the data obtained, the average peak molecular weight of TPC3‐1 was about 120 kDa. TPC3‐1 was composed of L ‐arabinose, D ‐ribose, D ‐xylose, D ‐glucose and D ‐galactose with a molar ratio of 4.9:2.2:3.1:1.8:1.0. Fifteen amino acids were identified as components of the polymer. The TPC3‐1 molecule was found to have an anomeric carbon sign of both α and β configurations and high‐branched chains. The network structure of TPC3‐1 was observed. CONCLUSION: The tea polysaccharide TPC3‐1 was an acid protein‐bound polysaccharide with an image of network structure. The results presented here will facilitate further study of the relationship between the chemical structure and biological role of tea polysaccharide. Copyright © 2008 Society of Chemical Industry     

Influence of some bioregulators on quality traits of pruned tea (Camellia sinensis (L) O Kuntze)

During investigation, it was observed that all the applied bioregulators, namely, jibika, IAA, cycocel, thiourea, methanol, succinic acid and sucrose, have a significant effect on quality parameters such as polyphenol oxidase (PPO) activity, caffeine, crude protein, starch, nitrogen, carotenoid and ascorbic acid (vitamin C) content over the control. However, maximum PPO activity was observed with cycocel followed by succinic acid, jibika, thiourea and sucrose during the first phase of spray while at the second phase PPO was maximal in sucrose-treated bushes followed by cycocel, jibika, thiourea and succinic acid. The caffeine content was found to be maximal in methanol followed by cycocel, IAA, thiourea and jibika as compared to the control during the first phase of spray. Similarly, nitrogen content increased due to methanol application at both the phases. Starch and carotenoid content were significantly influenced by jibika treatment. Likewise, ascorbic acid content was highest in sucrose-treated bushes as compared to other treatments. © 1998 SCI.     

Effect of green and black teas (Camellia sinensis L.) on the characteristic microflora of yogurt during fermentation and refrigerated storage

The effect of tea on the fermentation and survival of yogurt microorganisms was studied. Green and black teas were added to milk at the beginning of fermentation. Acidity of yogurt products and survival of their microflora were studied during 42 days at 4 °C. Results showed that the presence of tea did not significantly (P < 0.05) influence the yogurt characteristic microorganisms. HPLC studies demonstrated that yogurt bacteria did not affect tea catechins when they were incubated together for 48 h. Indeed, all five products reached about 10⁹ CFU/ml after 6 h of fermentation. Viability during 6 weeks storage at 4 °C varied very little (8.35 < log CFU/ml < 8.65). Similarly, green and black teas had no effect on lactic acid levels of the final products (after 6 weeks of storage, acidity remained above 80 °D). According to these findings, addition of teas or tea catechins to yogurt can be recommended to take advantage of their beneficial properties on human health attributed to their antioxidant and antimicrobial activities.     

Lead contamination in different varieties of tea plant (Camellia sinensis L.) and factors affecting lead bioavailability

BACKGROUND: There has been increasing concern in recent years about the concentration of lead (Pb) in tea. However, little research has been done to address questions concerning the distribution of Pb in different varieties of tea plant and the differences among tea plant varieties in their uptake and accumulation of Pb from the soil. Therefore the aim of this study was to investigate the accumulation of Pb in different tea plant varieties and the factors affecting Pb bioavailability. RESULTS: Three patterns of Pb distribution could be observed in different plant parts among the eight tea varieties surveyed, as well as a linear relationship between the Pb concentration in fine roots and the exchangeable Pb fraction in the corresponding soil. The uptake of Pb by fine roots increased significantly as the soil pH decreased. The average ratios of Pb concentration in fine roots to those in young stems and young leaves were 5.18 and 31.80 respectively. In fine roots the Pb concentration varied from 22.7 to 61.6 mg kg^?1. CONCLUSION: The results indicated that the uptake, transport and accumulation of Pb by tea plant organs were strongly governed by soil conditions and tea variety, thus providing tea producers with useful information on variety selection for the production of quality teas containing low levels of Pb. Copyright © 2010 Society of Chemical Industry     

Fatty acids in tea shoots (Camellia sinensis (L.) O. Kuntze) and their effects on the growth of retinal RF/6A endothelial cell lines

Chemo-protective effects of tea on ocular diseases were recorded in Chinese pharmacopoeia about 2000 years ago by eating tea. In the present study, contents of fatty acids (FAs) in tea shoots were determined by capillary GC; and the growth of RF/6A cells was also investigated by exposure to various representative FAs existing in tea shoots with pathologically relevant concentrations (40-500 microM) by ameliorated MTT assay and flow cytometry. Electron spin resonance (ESR) was used to measure oxygen consumption and investigate the free radical scavenging ability of linoleic acid (LA). Results showed that the most abundant long chain FAs were palmitic, linoleic, and alpha-linolenic acid in tea shoots; some RF/6A cells became suspended in culture medium treated by a high dose of both saturated and unsaturated FAs, but no apoptosis was observed. Moreover, it seemed that those FAs with different structure had various effects on the cell proliferation at their relatively low concentrations, LA expressed antioxidant activity in this study, which might be an important mechanism on the protection of eyes.     

Variations in the leaf standard,chemical composition and quality of black tea (Camellia sinensis) due to plucking intervals

Green leaf standard, chemical composition and quality of black tea (Camellia sinensis (L) O Kuntze) change with plucking intervals. Long plucking intervals lead to poor leaf standard with a lot of mature leaves and lower theaflavins, the sum of volatile flavour compounds imparting a sweet flowery aroma (group II volatile flavour compounds), caffeine contents and tasters' evaluations of black tea. The sum of volatile flavour compounds imparting inferior, grassy, green flavour (group I volatile flavour compounds) to tea, however, increases with long plucking intervals.     

高温高压提取茶汤加工普洱茶膏的研究

普洱茶膏是云南独特的速饮茶叶产品,但目前采用大锅熬制的工艺提取茶汤,导致产品的香气低、滋味淡薄,亟需改进提取方法。本文应用高压灭菌锅和响应面设计,开展高温高压(121℃、103kPa)提取茶汤加工茶膏研究。优化发现在浸提温度为113℃,茶水比1∶41g/mL,时间14min的条件下,提取茶汤的茶多酚、氨基酸、水浸出物含量最高,分别为20.89%±0.81%、3.82%±0.35%和37.89%±5.35%。按优化条件提取茶汤、减压浓缩、干燥加工制成茶膏有效成分含量与感官评审得分均优于大锅熬制加工的茶膏。本研究表明高温高压提取茶汤可以改进茶膏品质,在速饮茶叶产品加工中具有一定的应用前景。      

Effect of weather conditions on concentration of calcium,manganese, zinc,copper and iron in green tea (Camellia sinensis (L) O kuntze) leaves of North-Western India

Variations of calcium, manganese, zinc, copper and iron contents in green tea leaves due to weather conditions were studied for three cropping seasons with a view to provide information on nutritional requirements to boost productivity. The concentrations of these micronutrients were related to the uptake capability of tea plants as affected by different weather parameters. High temperature and high atmospheric evaporative demand assisted calcium uptake whereas high humidity and high rainfall reduced it. Low temperature and high humidity reduced manganese uptake. High weekly evaporation, weekly relative humidity and accumulated rainfall depressed the uptake of zinc, copper and iron in green tea shoots.