Leaching and bioavailability of aluminium, copper and manganese from tea (Camellia sinensis)

To assess human exposure to Al, Cu and Mn from tea drinking, eight tea samples were analysed for their ‘total’ and soluble elemental content. From this data, the percentage of ‘available’ element to the human system was calculated. Results for the samples showed that, compared to background levels for plants, concentrations of Al were highly elevated. The solubility of Al, Cu and Mn in infusions at 2, 5 and 10 min with boiling water showed that the solubility in the first infusion was the highest followed by the second and the third infusions in decreasing order. Calculation of percentage ‘available’ Al, Cu and Mn to the human system showed that tea is a rich source of dietary Mn, contributes towards our dietary copper intake, and is of no cause for concern in terms of Al toxicity in healthy individuals.     

Uptake of fluoride by tea plant (Camellia sinensis L) and the impact of aluminium

Tea plant (Camellia sinensis L) accumulates large amounts of fluoride in mature leaves from soils of normal fluoride availabilities, but the properties of fluoride absorption by this plant species are not well understood. The present study examined the characteristic of fluoride uptake by tea plants and the impact of Al with solution and soil experiments. The results showed that the fluoride taken up by tea plants was largely and readily transported, in particular to the leaves. The fluoride in leaves increased linearly with fluoride concentrations in the uptake solution (R² = 0.75, P < 0.001) or in the soil (R² = 0.88, P < 0.001), whereas those in root and stem were only marginally influenced. Including Al in solution or adding Al to the soil apparently increased the uptake and translocation of fluoride to the leaves. The concentrations of fluoride in the leaves were significantly (P < 0.05) increased by 19.1% or 37.7% when 18.5 µmol l^?1 Al or 74.1 µmol l^?1 Al respectively was included in the uptake solution, compared with the control without Al during an uptake period of 22 h. Similarly, Al application (100 mg kg^?1) to soil led to significantly higher fluoride concentrations in mature leaves and new shoots (one bud with three leaves). By contrast, the concentrations of Al in leaves in solution and soil experiments were not affected by fluoride and Al treatments. Nevertheless, higher Al concentrations after Al and fluoride additions were observed in the new shoots in soil experiments. Copyright © 2003 Society of Chemical Industry     

单核苷酸多态性在茶树中应用的研究进展

茶树原产于中国西南地区,是一种重要的经济作物。茶叶作为中国的传统饮品,是世界上三大无酒精饮料之一。长期的自然演化及自交不亲和使得茶树的种质资源极其丰富。单核苷酸多态性(single nucleotide polymorphism,SNP)是基因组水平上单核苷酸突变引起的基因序列多样性,是继限制性酶切片段多态性(restriction fragment length polymorphism,RFLP)和简单序列重复(simple sequence repeat,SSR)的第3代分子标记,广泛存在于生物基因组中。SNP分子标记作为最重要的分子标记技术对遗传学研究有极其重要的作用。本文介绍了SNP分子标记的特征,综述了SNP在茶树中的开发检测方法,研究应用于分子标记、基因定位、关联分析等,旨在为理解和研究SNP分子标记在茶树中的研究应用提供参考。     

Essential oil composition of commercial black tea (Camellia sinensis)

The essential oil components of different tea brands were investigated by gas chromatography. The oil yields of dried tea samples were ranged from 0.09% to 0.63%. Twenty-five compounds from Supreme and Lipton Yellow Label tea brands representing 98.0% and 88.0% of the Camellia sinensis oil were identified, respectively. The main ones were β-pinene (51.2%) and α-pinene (30.2%). Nineteen components from Tapal tea brand representing 76.7% of the C. sinensis oil were determined with high contents of muurol-5-en-4-a-ol (10.5%) and muurol-5-en-4-b-ol (31.3%). Fifteen components from Deer and Diana tea brands were identified, accounting for 83.3% and 78.2% of the oil containing α-cadinol and β-pinene. Seventeen components from non-branded teas were determined with high contents of muurol-5-en-4-a-ol and muurol-5-en-4-b-ol. Twenty-one compounds from non-branded Bangladeshi Shezan and Indian teas were also identified. All oils consisted of monoterpenic hydrocarbons, oxygenated monoterpenes and sesquiterpenes.     

Differentiation of eight tea (Camellia sinensis) cultivars in China by elemental fingerprint of their leaves

BACKGROUND: Tea is an infusion made from dried leaves of tea (Camellia sinensis) and can be a good dietary source of essential trace metals for humans. Therefore, it is necessary to consider variations in element content of tea leaves among tea cultivars. Thus, elemental fingerprint techniques, based on elemental contents (Al, B, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, P, Pb, and Zn) determined by inductively coupled plasma atomic emission spectrometry (ICP‐AES) and multivariate statistical analysis, have been used to differentiate eight tea cultivars. RESULTS: The ranges of element concentrations in leaves of the eight cultivars were in good agreement with those obtained in previous studies and the level of most elements in tea leaves was significantly different among cultivars. The classifications of eight tea cultivars were 100% accurate in total by principal component analysis (PCA), hierarchical cluster analysis (HCA), linear discriminant analysis (LDA), and back‐propagation neural network (BPNN) analysis. CONCLUSION: Each cultivar presented a distinctive element fingerprint and the elements in tea leaves can be significant predictors in differentiating tea cultivars. Copyright © 2009 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.     

Isolation and identification of spermidine derivatives in tea (Camellia sinensis) flowers and their distribution in floral organs

BACKGROUND: Recently, tea (Camellia sinensis) flowers have attracted increasing interest because of their content of bioactive compounds such as catechins. The aim of this study was to investigate the occurrence of some characteristic compounds in tea flowers. RESULTS: A principal component analysis of metabolites using ultra‐performance liquid chromatography/time‐of‐flight mass spectrometry showed differences in metabolite profile between flowers and leaves of C. sinensis var. Yabukita. Four spermidine derivatives were isolated from tea flowers. One of them was determined as N¹,N⁵,N¹⁰‐tricoumaroyl spermidine based on NMR, MS and UV data. The other three were identified as feruoyl dicoumaroyl spermidine, coumaroyl diferuoyl spermidine and triferuoyl spermidine based on MSⁿ data. Tricoumaroyl spermidine as the major spermidine conjugate was not detected in tea leaves. Furthermore, it decreased during floral development and mainly occurred in anthers. CONCLUSION: This study has provided the first evidence that spermidine‐phenolic acid conjugates occur in tea flowers in considerable amounts. Their presence should prompt a reconsideration of the ecological role of tea flowers. From an economic point of view, tea flowers might be suitable as a raw material in the healthcare food and pharmaceutical industries. Copyright © 2012 Society of Chemical Industry     

Understanding the biosyntheses and stress response mechanisms of aroma compounds in tea (Camellia sinensis) to safely and effectively improve tea aroma

Abstract

Metabolite formation is a biochemical and physiological feature of plants developed as an environmental response during the evolutionary process. These metabolites help defend plants against environmental stresses, but are also important quality components in crops. Utilizing the stress response to improve natural quality components in plants has attracted increasing research interest. Tea, which is processed by the tender shoots or leaves of tea plant (Camellia sinensis (L.) O. Kuntze), is the second most popular beverage worldwide after water. Aroma is an important factor affecting tea character and quality. The defense responses of tea leaves against various stresses during preharvest (tea growth process) and postharvest (tea manufacturing) processing can result in aroma formation. Herein, we summarize recent investigations into the biosyntheses of several characteristic aroma compounds prevalent in teas and derived from volatile fatty acid derivatives, terpenes, and phenylpropanoids/benzenoids. Several key aroma synthetic genes from tea leaves have been isolated, cloned, sequenced, and functionally characterized. Biotic stress (such as tea green leafhopper attack) and abiotic stress (such as light, temperature, and wounding) could enhance the expression of aroma synthetic genes, resulting in the abundant accumulation of characteristic aroma compounds in tea leaves. Understanding the specific relationships between characteristic aroma compounds and stresses is key to improving tea quality safely and effectively.

     

Enantioselectivity and residue analysis of fipronil in tea (Camellia sinensis) by ultra-performance liquid chromatography Orbitrap mass spectrometry

ABSTRACT

This study aimed to determine the residues of fipronil, metabolites, and enantiomers in tea (Camellia sinensis) during tea planting and green tea manufacture. An AD-RH chiral column was used to separate the fipronil enantiomers. During tea planting, the half-lives of the sum of fipronil and metabolites were similar to those of fipronil, which were 2.37 and 3.88 days for tea shoots and mature leaves, respectively. The residues of fipronil and its metabolites increased 2.3–3.6-fold during green tea manufacture. The values for the processing factors of fipronil and metabolites ranged from 1.0 to 2.1. A slightly significant enantioselectivity of (R)- and (S)-fipronil was observed during tea planting and green tea manufacturing. The residue pattern indicated that fipronil should not be applied in tea gardens due to its long persistence. The maximum residual limits of fipronil and metabolites at 2 μg kg^?1 were considered optimal.     

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.     

Rapid analysis of sulphur in wheat grain by X-ray fluorescence spectrometry

The accurate analysis of sulphur and sulphur compounds in plant material has become a critical issue as a consequence of reduced availability of the element from the environment. A new application of a reproducible technique has been developed for the determination of sulphur in wheat grain using X-ray fluorescence spectrometry. This new application compares favourably with traditional wet chemical methods especially as it is non-destructive. The sulphur content in wheut yruin measured by X-ray ffuorescence spectrometry was found to have a lower variability and the speed of analysis was more rapid in comparison with the chemical method, enabling a faster throughput of samples. Because sample preparation is very important for accurate analysis, the problems associated with oven drying, milling and of pressing during pellet formation are discussed.     

Variations of the chemical composition of clonal black tea (Camellia sinensis) due to delayed withering

The chemical composition of black teas (Camellia sinensis L) varies when the green leaf from which they are manufactured is withered physically to the same degree but for different periods. Caffeine contents progressively increase with prolonged withering time whereas theaflavins decrease due to prolonged withering. Although the sums of group I and group II volatile flavour compounds (VFC) decrease with prolonged withering time, the flavour index (expressed as group II VFC/group I VFC) increases due to prolonged withering. No significant changes were noted in the thearubigin levels with variation in withering time, but the tasters' evaluations were at a maximum for teas withered for 14 h. Subsequently the evaluation decreased with longer withering times.     

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     

Analysis of the theaflavin composition in black tea (Camellia sinensis) for predicting the quality of tea produced in Central and Southern Africa

A parameter of black tea that correlates with quality is highly desired. Twenty good and 20 poor quality tea clones were selected from the breeding programme at the Tea Research Foundation (Central Africa) (TRF(CA)). The theaflavin (TF) composition of the black tea manufactured from each clone was analysed by capillary electrophoresis and correlated with total scores and valuation from two tea tasters with regression analysis. The significance of the differences between the 20 good and 20 poor quality tea clones was determined with the Student t‐test and the distribution‐free Kruskal–Wallis test. The sum of the TFs of the black tea correlated well (r = 0.785, P = 0.0002) with the value of the tea. Of the individual TFs determined in the black tea, the highest correlation was obtained with TF‐3′‐monogallate (TF‐B) (r = 0.788, P = 0.0016), TF‐3‐monogallate (TF‐A) (r = 0.741, P = 0.0004) and free TF (TF‐f) (r = 0.705, P = 0.0002). TF‐B (m = 24.90) followed by TF‐A (m = 12.48) showed the steepest slopes against value, making them good indicators for value. The TF‐digallate (TF‐dg) content did not show significant correlation with value (r = 0.316, P = 0.358). The individual TF content thus can be used for optimising the black tea manufacturing process in Central and Southern Africa. © 2002 Society of Chemical Industry     

白叶单枞黑茶抗氧化及体外降血糖活性研究

采用DPPH法、FRAP法和α-胰淀粉酶、α-葡萄糖苷酶抑制活性评价白叶单枞黑茶醇提物及其不同萃取物的抗氧化活性及体外降血糖活性。结果表明,乙酸乙酯萃取物中总黄酮及总酚含量最高,分别为（155.68±4.34）mg/g（以芦丁当量计）和（313.84±9.79）mg/g（以没食子当量计）;乙酸乙酯萃取物DPPH·清除活性的EC50为13.72μg/mL,FRAP铁离子还原能力EC1为43.38μg/mL;同时该萃取物也具有最强的体外降血糖活性,5mg/mL时对α-胰淀粉酶抑制率为95.83%,50μg/mL时对α-葡萄糖苷酶抑制率为91.30%。采用HPLC-DAD-MS/MS对乙酸乙酯萃取物进行分析,通过对紫外吸收光谱以及质谱信息进行分析,并参考相关文献,推定出12个化合物,这些化合物中包括茶生物碱以及多种以芹菜素、山奈酚为苷元的黄酮糖苷类成分。