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J Food Sci Technol

Title:		Flavor characteristics and chemical compositions of oolong tea processed using different semi-fermentation times
Author(s):		Liu PP; Yin JF; Chen GS; Wang F; Xu YQ;
Address:		"1Tea Research Institute Chinese Academy of Agricultural Sciences, Key Laboratory of Tea Biology and Resources Utilization, Ministry of Agriculture, 9 South Meiling Road, Hangzhou, 310008 China. ISNI: 0000 0004 0369 6250. GRID: grid.418524.e 2Institute of Fruit and Tea, Hubei Academy of Agricultural Science, Wuhan, 430064 China. ISNI: 0000 0004 1758 5180. GRID: grid.410632.2"
Journal Title:		J Food Sci Technol
Year:		2018
Volume:		20180112
Issue:		3
Page Number:		1185 - 1195
DOI:		10.1007/s13197-018-3034-0
ISSN/ISBN:		0022-1155 (Print) 0975-8402 (Electronic) 0022-1155 (Linking)
Abstract:		"Flavor characteristics and chemical compositions of Tieguanyin oolong tea processed using different semi-fermentation times were investigated. Six flavor attributes of the teas, namely, astringency, bitterness, umami, sweet aftertaste, floral flavor, and green fruity flavor, were analysed. With extended semi-fermentation time, the taste intensity of sweet aftertaste increased, and the aroma intensity of floral and green fruity flavors increased, while the intensities of astringency, bitterness, and umami showed no clear trend. With increasing semi-fermentation time, the concentrations of gallated catechins, myricetin-rhamnose, quercetin-rutinoside, myricetin, and theanine greatly decreased, while those of total theaflavins, vitexin-rhamnose, kaempferol-galactose, kaempferol-rutinoside, vitexin, quercetin, and kaempferol increased significantly. The intensity of bitter taste was positively correlated with the concentrations of total catechins and gallated catechins. The intensity of astringent taste strongly correlated with the flavonoid concentrations, and that of sweet aftertaste positively correlated with the concentrations of (-)-epigallocatechin and (-)-epicatechin. However, dose-over-threshold analysis revealed that catechins, theaflavin, flavonol glycosides, and caffeine are the main taste-active compounds contributing to the taste of Tieguanyin oolong tea. The concentrations of total volatiles and most of the esters increased markedly with the semi-fermentation time, while the concentrations of low aldehydes showed a significant decrease. The flavor index was consistent with the intensity of floral aroma, increasing from 0.59 (12 h) to 0.84 (24 h) and then decreasing to 0.63 (32 h). Results of this work suggest that the flavor change is mainly due to the variation of taste-active and aroma-active compounds in oolong tea"
Keywords:		Chemical compounds Flavor attributes Semi-fermentation Tieguanyin oolong tea;
Notes:		"PubMed-not-MEDLINELiu, Pan-Pan Yin, Jun-Feng Chen, Gen-Sheng Wang, Fang Xu, Yong-Quan eng India 2018/03/01 J Food Sci Technol. 2018 Mar; 55(3):1185-1195. doi: 10.1007/s13197-018-3034-0. Epub 2018 Jan 12"