Differentiation of ethanol–water clusters in Fenjiu by two-dimensional correlation fluorescence and Raman spectra

Abstract

The taste of different flavor liquor is multifarious, but the same brand liquor with different quality is truth. The essence of supramolecular ethanol–water clusters and their intrinsic structural differences in three kinds of Fenjiu are studied by two-dimensional correlation spectra (2D-COS) of fluorescence and Raman. The 2D-COS of fluorescence reveals the prominent emission peaks of three Fenjiu are apparently different. The central fluorescence peak of Fenjiu (a) is located at 330 nm, corresponding to the cluster of (H2O)m(EtOH)n. In Fenjiu (b), the emission peak appears near 310 nm, while those of Fenjiu (c) appear mainly near 310 and 373 nm, corresponding to the clusters of (H2O)(EtOH)n and (H2O)m(EtOH), respectively. Based on 2D-COS of Raman, the peak of Fenjiu (b) at 3440 cm−1 changes initially, indicating its disorder degree is getting higher with continuous dilution with water. However, along with the dilution of Fenjiu (a) and Fenjiu (c), the peak located near 3200 cm−1 changes in priority, indicating that the degree of association between ethanol and water is high, and the clusters formed there are stable. Therefore, this work provides the combined methods to distinguish different supramolecular sets in Fenjiu, applying liquor differentiation in the future.