基于SDE和HS-SPME/GC-MS的乌龙茶香气组成特征分析

为更好地分析乌龙茶香气组成特征,本试验应用气相色谱-质谱联用（GC-MS）检测平台,分别考察了同时蒸馏萃取法（SDE）和顶空固相微萃取法（HS-SPME,3种不同纤维涂层萃取头）对3个福建代表性乌龙茶样品（铁观音、肉桂和水仙）香气成分的萃取效果。结果表明,采用不同香气成分萃取方法可从供试茶样检出262种香气成分,其中以肉桂香气种类最多（204种）,水仙其次（175种）,铁观音最少（120种）。应用HS-SPME干样萃取法可获得最多种类的检出成分（186种）,其次为HS-SPME湿样萃取法（139种）,并以SDE法检出成分最少（33种）。不同萃取方法对香气成分的检出存在良好的互补作用,但以基于HS-SPME干样萃取法,应用65βμm PDMS/DVB（聚二甲基硅氧烷/二乙烯基苯）萃取头进行检测分析可相对较好地反映3种供试茶样香气化学组成特征,并能实现橙花叔醇、吲哚、α-法呢烯、苯乙醇、苯乙腈、水杨酸甲酯等多种乌龙茶常见或特征香气成分的重复性检测。肉桂和水仙茶样相较铁观音茶样的香气种类和数量存在较大差异,且以肉桂茶样的香气组成更为复杂多样,该结果与闽南乌龙茶与闽北乌龙茶迥然不同的花香品质及肉桂相较水仙拥有更为浓郁高显的香型特征相符合。

Aroma Profiling of Oolong Tea by SDE and HS-SPME in Combination with GC-MS

To better understand the aroma characteristics of oolong tea, the volatile compounds of three representative Fujian oolong tea samples (Tieguanyin, Rougui and Shuixian) were isolated by simultaneous distillation-extraction (SDE) and head space solids-phase microextraction (HS-SPME) coupled with three different fiber coatings, and analyzed by gas chromatography-mass spectrometry (GC-MS). 262 aroma components were detected by different extraction methods. The number of aroma components detected from high to low was 204 (Rougui), 175 (Shuixian), and 120 (Tieguanyin), respectively. HS-SPME with dry samples were detected with 186 aroma components, followed by HS-SPME with wet samples (139), and SDE method detected 33 aroma components. Different extraction methods can complement each other on the detection of aroma components. A 65βμm PDMS/DVB (Polydimethylsiloxane/Divinylbenzene) fiber showed good reproducibility, and some common or characteristic aroma components in oolong tea samples were robustly detected, such as nerolidol, indole, alpha-farnesene, phenylethyl alcohol, benzyl nitrile, methyl salicylate, etc. Compared with Tieguanyin, Rougui and Shuixian had higher number of aroma components, and the aroma compositions of Rougui were the most complex. These results were in consistent with the sensory evaluation of oolong tea produced from north and south of Fujian province, and Rougui showed higher aroma quality than that of Shuixian.