萎凋时间对“英红九号”白茶香气的影响

Effects of Withering Duration on the Aroma Profile of Yinghong No. 9 White Tea

采用顶空固相微萃取和气相色谱-质谱联用法,分析不同萎凋时间"英红九号"白茶香气化合物的组成及含量。结果表明,"英红九号"白茶的香气总量随萎凋时间的延长呈现先增后降趋势,萎凋24 h含量最高,达到858.40 ng/g。白茶香气主要由醇类、酯类、醛类、酮类和烃类组成,其中醇类化合物所占比例最大。不同萎凋时间白茶的香气化合物组成比较相似。顺-3-己烯-1-醇、芳樟醇、乙酸-顺-3-己烯酯、丁酸-顺-3-己烯酯、水杨酸甲酯、己酸-顺-3-己烯酯、己醛、苯甲醛、反,反-2,4-庚二烯醛、壬醛、反,反-3,5-辛二烯-2-酮、3,5-辛二烯-2-酮、β-紫罗兰酮、β-香叶烯、柠檬烯、反-β-罗勒烯和β-罗勒烯,这17种香气化合物在多数样品中含量较高,其含量总和占各样品香气总量的67.3%~76.0%,对香气总量变化影响较大;其中芳樟醇、水杨酸甲酯等多数化合物含量随着萎凋进行先增后降;而苯甲醛和β-香叶烯含量在30 h的萎凋过程中总体持续上升。

The aroma compounds of white tea samples produced from the cultivar Yinghong No.9with different withering durations were extracted by headspace-solid phase micro-extraction(HS-SPME)and analyzed by gas chromatography-mass spectrometry(GC-MS).The results showed that the total aroma content of white tea rose to a maximum level of858.40ng/g at24h and then declined with withering time.The aroma components identified included alcohols,esters,aldehydes,ketones and hydrocarbons with alcohols being the most abundant ones.All tea samples shared similar aroma components.A total of17aroma compounds,including(Z)-3-hexen-1-ol,linalool,(Z)-3-hexen-1-yl acetate,(Z)-3-hexen-1-yl butyrate,methyl salicylate,(Z)-3-hexen-1-yl hexanoate,hexanal,benzaldehyde,(E,E)-2,4-heptadienal,nonanal,(E,E)-3,5-octadien-2-one,3,5-octadien-2-one,β-ionone,β-myrcene,D-limonene,(E)-β-ocimene andβ-ocimene were found in relatively high levels in most of the samples,together accounting for67.3%-76.0%of the total aroma components.The17compounds were the main contributors to the aroma of white tea,most of which such as linalool and methyl salicylate demonstrated an initial rise followed by a decline while a few of them such as benzaldehyde andβ-myrcene increased continuously during the withering process.