红绿茶加工工艺对茶鲜叶香气和糖苷类香气前体的影响

为了研究不同的加工工艺对茶鲜叶香气和糖苷类香气前体的的影响,利用槠叶种群体的一芽二、三叶鲜叶为原料,按照传统的加工工艺分别制成红茶、绿茶,应用SDE提取、GC/MS对香气组成进行分析,同时应用溶剂提取、双相酶解和GC/MS对糖苷类香气前体物质进行系统分析。结果表明:由同一批鲜叶所制的绿茶和红茶,其香气和糖苷类香气前体在组成和含量上存在明显差异。鲜叶、绿茶和红茶中精油相对总量依次为17.263、5.004和34.702。糖苷类香气前体检测结果表明,鲜叶中的香气前体苷元有6种,分别为苯甲醇、反式-芳樟醇氧化物、芳樟醇、苯乙醇、水杨酸甲酯和香叶醇;绿茶中有5种,苯甲醇未检测出;而红茶中只检测出了反式-芳樟醇氧化物和苯乙醇两种。在绿茶加工中,鲜叶中的苷元仅有20.34%得以释放;而在红茶加工中,95.60%的苷元得以释放。这些释放出的苷元成为成品茶的重要香气组分。结果证实了鲜叶在不同的加工工艺处理下,在制得的成茶中香气和糖苷类香气前体的组成和含量存在明显差异。

Effects of Processing Techniques on Aroma and Glycosidic Aroma Precursors in Fresh Tea Leaves

To elucidate the effects of processing techniques on aroma and glycosidic aroma precursors in fresh tea leaves,fresh tea leaves with mixtures of one bud,two leaves and one bud,three leaves were plucked from Camellia Sinensis cv.zhuye at Shucheng tea plantation.The same batch of tea fresh leaves was divided into three batches and two of them were processed to green tea and black tea with the orthodox processing,respectively.The essential oils were extracted with SDE and analysis with GC/MS.Glycosidic aroma precursors were extracted and partially purified,then hydrolyzed with crude enzyme from fresh tea leaves in two-phase solvent system.The hydrolysis was extracted with ethyl ether and concentrated,analyzed and determined with GC/MS.The results showed that the component and content of aroma and glycosidic aroma precursors in fresh tea leaves,green tea and black tea are different.The total content of essential oils in fresh tea leaves,green tea and black tea was 17.263,34.702 and 5.004,respectively.The components of algycone were benzyl alcohol,trans-linalool oxide,linalool,phenyl ethanol,methyl salicylate and geraniol in fresh tea leaves while those in green tea was five kinds as those of fresh tea leaves excepted benzyl alcohol and those in black tea were only phenyl ethanol and trans-linalool oxide.Compared with fresh tea leaves,the content of total algycone reduced 20.34% in the green tea processing.However,the content of total algycone reduces 95.60% in black tea processing.In made tea,the released aglycone contributed to the principal aroma component.Those results indicated that the composition and content of aroma and glycosidic aroma precursors in made tea changed with processing techniques.