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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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    Phenolic composition and antioxidant activity of Sideritis lycia and Sideritis libanotica subsp. linearis: Effects of cultivation, year and storage
    (Elsevier GmbH, 2017) Dincer C.; Torun M.; Tontul I.; Topuz A.; Sahin-Nadeem H.; Gokturk R.S.; Tugrul-Ay S.
    Flowered verticillasters of Sideritis lycia Boiss. & Heldr. and Sideritis libanotica Labill. subsp. linearis (Benth.) Bornm. are used as herbal tea. In the present study, these plants were tried to be cultivated and phenolic composition and antioxidant activity of the wild and cultivated plants were compared. Total phenolics, flavonoids and antioxidant activity of S. lycia and S. libanotica subsp. linearis were found in the range of 16.05–18.04 and 9.16–10.49 g gallic acid equivalent/kg dw, 9.70–14.30 and 5.41–9.68 g catechin equivalent/kg dw and 6.57–8.71 and 13.88–19.04 g dw/g DPPH, respectively. Total flavonoid content and antioxidant activity of the wild plants were determined to be higher than cultivated samples. Major phenolic acids were p-coumaric, caffeic and ferulic acids, while the main flavonoids were quercetin, morin and apigenin. Consecutive harvesting year and storage period did not cause remarkable differences on the analysed parameters, in general. Phenolic compounds of the both plants were decreased during storage, in general. © 2016 Elsevier GmbH
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    Physicochemical properties of Turkish green tea powder: Effects of shooting period, shading, and clone
    (Turkiye Klinikleri Journal of Medical Sciences, 2014) Topuz A.; Dinçer C.; Torun M.; Tontul I.; Şahin-Nadeem H.; Haznedar A.; Özdemir F.
    This study aimed to determine the physicochemical properties of the green tea powders produced from 2 different Turkish tea [Camellia sinensis (L.) O.Kuntze] clones (Derepazari{dotless} 7 and Fener) grown under different shade levels and harvested during 2 consecutive shooting periods. Moisture, ash, crude fiber, and total phenolic contents of the green tea powders were determined based on the experimental factors. Products were also evaluated for their water activity, bulk density, particle size, color, extraction yield, and antioxidant activity. The shooting period, specific to Turkish tea cultivation, showed remarkable effects on the main quality parameters of the green tea powders. It is noteworthy that the phenolic content and antioxidant activity of the products did not change significantly with treatments. The green tea powder produced from Derepazari{dotless} 7 clone, grown under dark shade and harvested in the first shooting period, was superior among the tested parameters. © TÜBİTAK.