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    Comparative study on volatile compounds in Turkish green tea powder: Impact of tea clone, shading level and shooting period
    (2013) Tontul I.; Torun M.; Dincer C.; Sahin-Nadeem H.; Topuz A.; Turna T.; Ozdemir F.
    The objective of this study was to determine volatile compounds in green tea powders produced from a clone of two different teas (Camellia sinensis (L.) O. Kuntze) grown under different shade levels and harvested in two consecutive shooting periods. Both hydrodistillation and solid phase microextraction (SPME) methods were comparatively performed to identify maximum number and amount of volatile compounds. SPME method enables the identification of the greatest number of volatile compounds which principally comprise limonene, ?-terpineol and heptanal. A few specific volatile compounds were identified for differentiation of green tea samples depending on the treatments, such as, heptanal in 1st shooting period, ethyl benzene, xylene and benzenacetal for 2nd shooting period, and phytol and tridecane for shading treatments. The treatments were significantly clustered either as tea clones or shooting period by the volatile compounds i.e. linalool, ?-terpineol, 3-methylbutanal, 2-methylbutanal and p-cresol, 2,6-di-tert-buthyl determined in hydrodistillation method and tridecane, heptanal, linalool, nonanal, hexanal, ?-terpineol, 1-pentanol, pentanal, dimethylsulfide, 2,2,4-trimethylhexane, limonene and 1-hexanol in SPME method as shown by principal component analysis (PCA). © 2012 Elsevier Ltd.
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    Effect of rolling methods and storage on volatile constituents of Turkish black tea
    (John Wiley and Sons Ltd, 2017) Ozdemir F.; Tontul I.; Balci-Torun F.; Topuz A.
    The leaves of harvested tea [Camellia sinensis (L.) O. Kuntze] can be processed into different products such as black tea, green tea and oolong tea. Black tea is the mostly consumed worldwide among these products. Black tea production is achieved by a series of processing steps namely withering, rolling, fermentation, drying, sieving and packaging. Rolling is one of the most important steps in the production as it ensures uniform maceration of tea leaves and promotes oxidation reactions catalysed by phenol oxidase enzymes during the fermentation process. The rolling of tea leaves is generally performed by either Crushing-Tearing-Curling (CTC), rotorvane or Orthodox methods. However, in Turkey, rolling is also performed using a combination of rotorvane and orthodox which is called the “ÇAYKUR” method. The rolling method provides a unique taste and flavours. Thus, this study was conducted to compare volatile constituents of the black teas produced by the above rolling methods and to determine the volatiles during the 6-month storage period. Some specific compounds such as 2,6-nonadienal, 3-hexen-2-one and dodecanal for ÇAYKUR, 2,5-octanedione for Orthodox and methylpyrazine for CTC were identified to differentiate the rolling system. This study also showed that a few compounds can be used as markers of storage. The number and amounts of volatiles, especially compounds with a high molecular weight, increased by storage. In addition, the flavour quality of the teas was evaluated by the Wickremasinghe–Yamanishi ratio (WYR), Mahanta ratio (MR) and Owuor Flavour Index. Copyright © 2017 John Wiley & Sons, Ltd.