Flavor characteristics and chemical compositions of oolong tea processed using different semi-fermentation times
Flavor characteristics and chemical compositions of oolong tea processed using different semi-fermentation times
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不同半发酵时间乌龙茶的风味特征及化学成分
DOI：
10.1007/s13197-018-3034-0
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发表时间：
2018-03-01
影响因子：
3.1
通讯作者：
Xu, Yong-Quan
中科院分区：
文献类型：
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作者：
Liu, Pan-Pan;Yin, Jun-Feng;Xu, Yong-Quan
研究了不同半发酵时间铁观音乌龙茶的风味特征和化学成分。分析了茶的六种风味属性，即涩味、苦味、鲜味、甜味回味、花香和绿色果味。随着半发酵时间的延长，甜的后味强度增加，花香和绿色果香的香气强度增加，而涩味、苦味和鲜味的强度变化趋势不明显。随着半发酵时间的延长，没食子儿茶素、杨梅素-鼠李糖、槲皮素-芸香糖苷、杨梅苷和茶氨酸的含量显著降低，而总茶黄素、牡荆素-鼠李糖、山奈酚-半乳糖、山奈酚-芸香糖苷、牡荆素、槲皮素和山奈酚的含量显著升高。苦味的强度与总儿茶素和没食子酸儿茶素的浓度呈正相关。涩味的强度与黄酮类化合物的浓度密切相关，甜味的回味与表没食子儿茶素和表儿茶素的浓度呈正相关。然而，剂量超过阈值分析表明，儿茶素，茶黄素，黄酮醇苷，咖啡因是主要的味道活性化合物有助于铁观音乌龙茶的味道。随着半发酵时间的延长，总挥发物和大部分酯类物质的浓度显著增加，而低级醛类物质的浓度则显著降低。风味指数与花香的强度一致，从0.59（12 h）增加到0.84（24 h），然后下降到0.63（32 h）。研究结果表明，乌龙茶的风味变化主要是由于呈味活性物质和香气活性物质的变化。
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.