Abstract
Acids and esters are the main aromatic compounds in Baijiu. These compounds affect primarily the flavor and quality of Baijiu. The detection of these compounds is important for the control of Baijiu. Although FTIR spectroscopy has gradually been used to detect Baijiu in recent years, this technology has not been directly employed to measure the infrared spectra of acids and esters in Baijiu. In this paper, a novel FTIR difference spectroscopy is proposed to extract the infrared spectra of acids and esters in Baijiu. This difference spectrum is mainly obtained by subtracting the FTIR spectra of aqueous ethanol from that of Baijiu. The FTIR spectra of some kinds of Baijiu were measured, and the infrared spectra of acids and esters in Baijiu were obtained. The flavor of Baijiu can be distinguished through the difference spectra. Since the acquisition of FTIR spectra only takes less than one minute, this FTIR difference spectrum can be developed as a quick control method for Baijiu.