Insights into ethanol–water clusters in alcoholic beverages by vibration spectroscopy connecting with quality and taste

Alcoholic beverages are popular throughout the world, and numerous studies have been conducted on them. Albeit most investigations focusing on composition and evolution of flavor components, several studies have suggested that the tastes and/or qualities of them are not only determined by the type and content of involved ingredients but also influenced by the supramolecular clusters between ethanol and water. However, insights into supramolecular ethanol–water clusters (E-Wc) in alcoholic beverages, especially the intrinsic relationship of them to organoleptic sensing and quality assessment, have not been elucidated systematically up to now. This review summarized the studies exploring the supramolecular E-Wc in several types of alcoholic beverages, which were revealed essentially by means of vibrational spectroscopic techniques such as infrared/near-infrared absorption and Raman scattering spectra. From different aspects and levels they revealed the structures of supramolecular E-Wc, as well as, the hydrogen bonds (HBs) strength in alcoholic beverages, respectively. Besides, two-dimensional correlation analysis has also been used as a powerful tool in the studies of alcoholic beverages which has revealed important structural information being hidden in the original spectra. Finally, beyond identifying a number of important supramolecular E-Wc by spectroscopy, the prospects and challenges in this field were also briefly discussed in the hope that it would be of interesting and help to more researchers in the fields of liquid science.