底圩茶风干叶香气的判别分析

Discriminant Analysis of Aroma of Air Dried Leaves of Dixu Tea

[目的]采用电子鼻技术对13个底圩优良群体种的风干叶香气进行研究。[方法]利用主成分分析(PCA)与线性判别分析(LDA),对底圩茶新梢和成熟叶的干茶、茶汤和叶底香气物物质进行分析和判别。[结果]电子鼻技术对13个底圩优良群体种风干叶均有较好的响应。PCA分析表明,新梢干茶和茶汤的贡献率分别为99.85%、99.85%,高于成熟叶干茶和茶汤的贡献率(99.32%、99.71%),叶底则相反,新梢贡献率(99.84%)低于成熟叶贡献率(99.94%);LDA分析表明,新梢干茶和茶汤贡献率(85.44%、91.62%)高于成熟叶干茶和茶汤贡献率(77.92%、88.87%),叶底新梢贡献率(98.09%)低于成熟叶(98.17%);PCA贡献率均高于LDA,则PCA较LDA更能明显地区分13个底圩优良群体种风干叶的香气。通过电导率G/G_(0)值可以判别出硫化物挥发性成分为底圩茶第一主要成分,芳香成分、有机硫化物为第二主要成分,氮氧化合物为第三主要成分。[结论]应用电子鼻技术对13个底圩优良群体种的香气鉴定是可行的,有望在底圩茶检测领域得到使用。

[Objective]The electronic nose technology was used to study the aroma of dried leaves of 13 species with good bottom Dixu.[Method]Principal component analysis(PCA)and linear function discriminant analysis(LDA)were used to analyze and discriminate the dry tea,tea soup and aroma substances at the bottom of new shoots and mature leaves of Base Dixu tea.[Result]The electronic nose technology had a good response to the air dried leaves of 13 base Dixu superior population species.The PCA contribution rates of fresh shoot dry tea and tea soup were 99.85%and 99.85%,respectively,which were higher than those of mature leaf dry tea and tea soup(99.32%and 99.71%),on the contrary,the contribution rates of fresh shoot(99.84%)were lower than those of mature leaf(99.94%).The contribution rate of LDA fresh shoots and tea soup(85.44%,91.62%)was higher than that of mature leaves and tea soup(77.92%,88.87%),while the contribution rate of LDA fresh shoots(98.09%)was lower than that of mature leaves(98.17%).PCA contribution rates were higher than LDA.PCA was more effective than LDA in distinguishing the aroma of the dried leaves of the 13 best populations.According to G/G_(0) value of electrical conductivity,it could be distinguished that the volatile component of sulfide was the first main component of Dixu tea,the aromatic component,the organic sulfide was the second main component,and the nitrogen oxide was the third main component.[Conclusion]The application of electronic nose technology is feasible for aroma identification of 13 Dixu fine population species,and it is expected to be used in the field of Dixu tea detection.