Discrimination of Chinese teas according to major amino acid composition by a colorimetric IDA sensor

Abstract An efficient liquid sensor array was presented for tea differentiation through analysis of amino acid composition based on indicator displacement assays (IDA). After construction and deduction upon response to theanine and six other amino acids abundant in tea leaves, the sensor is capable of distinguishing 70 tea samples within four categories. Statistical analysis including Hierarchy Cluster Analysis (HCA) and Principal Component Analysis (PCA) suggested that successful discrimination of teas depended not only on overall amino acid concentration but also composition of related amino acid. The PCA results even indicated a negative correlation between the loading value in the first principal component and the amino acid content in tea leaves. Besides, differentiation of tea samples of the same category with different quality grades and geographical origins was also realized, demonstrating the versatility of the presented sensor array. Our study offered an alternative method to construct colorimetric sensor for cost-effective surveillance and control of tea related products.