A Hypothesis-Free Sensor Array Discriminates Whiskies for Brand, Age, and Taste

In biology, non-specific interactions are ubiquitous and important, whereas in chemistry, non-specificity or non-selectivity is suspect. We present simple tongues consisting of fluorescent polyelectrolytes or chimeric green fluorescent proteins (GFPs) to discriminating 33 different whiskies according to their country of origin (Ireland, US, or Scotland), brand, blend status (blend or single malt), age, and taste (rich or light). The mechanism of action for these tongues is differential quenching of the fluorescence of the poly(aryleneethynylene)s or the GFPs by the complex mixture of colorants (vanillin, vanillic acid, oak lactones, tannins, etc.; the interactome) extracted from the oak barrels and added caramel coloring. The differential binding and signal generation of the interactomes to the polymers and proteins result from hydrophobic and electrostatic interactions. The collected quenching data, i.e., the response patterns, were analyzed by linear discriminant analysis. Our tongues do not need any sample preparation and are equal or superior to state-of-the-art mass spectrometric methods with respect to speed, resolution, and efficiency of discrimination.