Application of electronic nose in identification for aging years of Liupao tea

ObjectiveThe application of electronic nose(EN) in identification for aging years of Liupao tea was re-searched to provide reference for establishing new quality evaluation technology system of Liupao tea. MethodResponse characteristic values of dry tea, tea infusion and wet tea leaf at different aging years from various producers were obtained by PEN3 portable EN smell analysis system. Principle component analysis(PCA) and linear discriminant analysis(LDA) were used to analyze their aging years and prediction model, and mahalanobis distance(MA),euclidean metric(EU) and discriminant function analysis(DFA) were applied in verification of accuracy of the prediction model. ResultLiupao tea of different aging years had different response signals on EN. The EN response values of 171-175,166-170 and 155-160 s were selected as the characteristic values for dry tea,tea infusion and wet tea leaf to establish the identification model. LDA was better than PCA in distinguishing Liupao tea of different aging years. Samples of different aging years distributed in di-fferent regions. The cumulative contribution rates of discriminant LD1 and LD2 for dry tea,tea infusion and wet tea leaf were 93.00%,88.31% and 80.52% respectively. The verification accuracy of identification model for dry tea with EU,MA and DFA reached 88.23%,88.23% and 94.12%,identification model for tea infusion all reached 82.35% and for wet tea leaf reached 70.58%,82.35% and 94.12%. ConclusionEN can identify the smell characteristics such as aromatic substance in Liupao tea of different aging years, and realize distinguishing and classification. It can be used and promoted in the identification of tea aging years.