电子舌在工夫红茶甜纯滋味特征评价中的应用

Application of Electronic Tongue in the Evaluation of Sweet Taste Quality of Congou Black Tea

为了更客观、快速、准确地评价工夫红茶的甜纯滋味特征,首先以专家人工感官审评为依据,根据茶汤滋味特点将工夫红茶分为甜纯、纯正、欠纯3组。然后采用电子舌分析并结合多元统计分析手段综合评价茶汤滋味,并建立甜纯滋味判别方程。最后,对验证集中的工夫红茶开展电子舌分析进行验证。结果表明:基于电子舌响应的主成分分析、偏最小二乘判别分析揭示电子舌可有效区分滋味甜纯或非甜(纯正、欠纯)工夫红茶,且影响甜纯滋味识别的关键电子舌传感器为SWS甜味传感器(P<0.001,单因素方差分析)。基于二元逻辑回归构建甜纯滋味判别预测方程,且整体预测准确率达93.8%。此外,验证集茶样的电子舌分析结果进一步证实电子舌用于评判工夫红茶甜纯滋味的有效性。综上,本研究采用电子舌技术实现了对工夫红茶甜纯滋味特征的快速、准确判别评价,为后续茶叶滋味特征成分的研究提供理论依据,亦可为茶汤滋味的客观、智能评价提供依据。

The major purpose of this study was to evaluate the sweet taste quality of Congou black tea objectively, rapidly and accurately. According to sensory evaluation data obtained from experts, Congou black tea samples were divided into three categories, i.e., sweet, pure and with off-flavor. Next, the taste quality of tea infusions was comprehensively evaluated by using electronic tongue in combination with multivariate statistical analyses such as principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA) and one-way analysis of variance (ANOVA). A model was established for the discrimination of sweet taste from non-sweet taste based on analysis of electronic tongue data by using binary logistic regression. Finally, the obtained results were preliminarily validated using a separate set of black tea samples. Results: PCA and PLS-DA based on the responses of electronic tongue sensors provided clear discrimination between sweet and non-sweet (pure and with off-flavor) black tea samples. The key electronic tongue sensor for taste classification was identified as the sweet taste sensor SWS (P < 0.001, by one-way ANOVA). A predictive equation for the sweet taste was established based on binary logistic regression, with an overall predictive accuracy of 93.8%. Furthermore, we confirmed the effectiveness of electronic tongue analysis by applying it to the tea samples in the validation set. In summary, the electronic tongue is able to rapidly and accurately evaluate the sweet taste of Congou black tea, and it provides a theoretical foundation for further studies of key taste components in tea, and also offers a novel tool for objective and intelligent evaluation of tea taste.