Ethanol evaporation drives ester assembly and particle deposition in droplets of Chinese distilled liquors

Abstract Chinese distilled liquor, known as Baijiu, typically has a relatively high ethanol content (52 or 53% alcohol by volume, ABV) and is characterized by a powerful, heady scent. When its alcohol content is less than 45% ABV, Baijiu loses its flavor and becomes cloudy and tasteless; thus, it is relatively bland and thin. Since this phenomenon has not been reasonably explained, the aim of this study is to determine its underlying mechanism by examining the droplet evaporation. A 1.0 µL of droplets were applied to the substrate surface for evaporation. The results revealed that a reduction in the alcohol content (<45% ABV) triggered the self‐assembly of unique long‐chain fatty acid ethyl esters into various nano‐ or microparticles with sizes ranging from 100 nm to 10 µm within the Baijiu droplets. These particles deposit under the influence of internal flow and exhibit Baijiu‐specific coffee‐ring effects after drying. Interestingly, these particles encapsulated the water‐soluble or insoluble flavor chemicals, resulting in the brightness and aroma/flavor of Baijiu decreased radically; this is the reason that a high alcohol content is needed in Baijiu. These findings offer new insights for the quality control of low‐alcohol Baijiu and Baijiu identification.