Colorimetric sensor array based on silver deposition of gold nanorods for discrimination of Chinese white spirits

The rapid and effective discrimination of Chinese white spirits is of great significance for quality control in the white spirit industry. Herein, we proposed a colorimetric sensor for white spirits based on silver deposition on gold nanorods (AuNRs), which were formed by reducing silver ions to Ag nanoshells on the surface of the AuNRs by different reductants containing hydroxyl or amino groups. The degree of inhibition of silver deposition was demonstrated to be strongly associated with the various components of white spirits, such as organic acids, aldehydes, ketones, and esters, which resulted in color differences and a consequent colorimetric response for different types of white spirits. The color differences could be recognized using principal component analysis (PCA), hierarchical cluster analysis (HCA), and linear discriminant analysis (LDA). The colorimetric sensor array was constructed by designing AuNRs with four different morphologies by utilizing different reducing agents to not only successfully distinguish various types of white spirits, including twelve types of strong-aroma-type spirits with similar flavor characteristics and different aroma-type spirits, but also to determine the concentration of the main ingredients affecting the quality of white spirits with a satisfactory linear range. Notably, the discriminating ability of the colorimetric sensor arrays was equal or superior than that of the untargeted metabolomic approach based on liquid chromatography-mass spectrometry. This sensing strategy, with facile preparation, fast response, excellent discrimination and high-throughput signal output, provides a promising application platform for real-time quality monitoring of white spirits and other alcoholic beverages.