Rapid Detection of Acids and Esters in Chinese Liquor by Fourier Transform Infrared Spectroscopy with Difference Spectroscopy
摘要
Although acids and esters are the trace chemical compounds in Chinese liquor, they affect primarily the flavor and quality of Chinese liquor. The detection of these compounds is important for the control of Chinese liquor. FTIR spectroscopy has gradually been used to detect Chinese liquor in recent years, but this technology has not been directly employed to measure the infrared spectra of acids and esters in Chinese liquor. In this paper, novel FTIR difference spectroscopy is proposed to extract the infrared spectra of acids and esters in Chinese liquor. This difference spectrum is mainly obtained by subtracting the FTIR spectra of aqueous ethanol from that of Chinese liquor. The FTIR spectra of some kinds of Chinese liquor were measured, and it was found that three vibrational peaks at ~ 1260 cm−1, ~ 1377 cm−1, and ~ 1710 cm−1, which were also observed in the infrared spectra of acids and esters in Chinese liquor, were obtained. The flavor of Chinese liquor can be distinguished through the difference spectra. Since the acquisition of FTIR spectra only takes less than 1 min, this FTIR difference spectrum can be developed as a quick control method for Chinese liquor.