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桑叶茶的挥发性成分直接关系其风味特征。采用顶空固相微萃取方法和气相色谱-质谱(GC/MS)联用分离鉴定技术,分析桑叶乌龙茶的挥发性成分,并对样品萃取条件进行优化。在萃取温度60℃、吸附时间40 min、250℃解吸5 min的条件下,获取样品的GC/MS分析数据的相对标准偏差(RSD)均<10%,其精密度和重现性较好。在桑叶乌龙茶样品中共检测到醛类、酮类、酯类、烯烃类和脂肪酸类化合物83种,其中醛类化合物的含量最高,占总挥发性物质的40%以上。主要挥发性成分甲基庚烯酮、正己醛、2-甲基丁醛、β-紫罗兰酮以及α-环柠檬醛对桑叶乌龙茶甜香清新、略带花果味的香气特征形成起决定性作用。
The volatile components of mulberry leaf tea directly related to its flavor characteristics. The volatile components of mulberry leaf Oolong tea were analyzed by headspace solid-phase microextraction and gas chromatography-mass spectrometry (GC / MS). The extraction conditions were optimized. The relative standard deviation (RSD) of GC / MS data was <10% under the condition of extraction temperature of 60 ℃, adsorption time of 40 min and desorption of 250 min at 5 min. The precision and reproducibility were good. Altogether 83 kinds of aldehydes, ketones, esters, olefins and fatty acids were detected in the mulberry leaf oolong tea samples, of which the aldehydes content was the highest, accounting for more than 40% of the total volatile matters. The main volatile components of methyl heptenone, n-hexanal, 2-methylbutyraldehyde, β-ionone and α-ring citral mulberry oolong tea sweet and fresh, slightly floral aroma characteristics play a decisive role .