Identification of Characteristic Aroma Compounds in Soy Sauce Aroma Type Xi Baijiu Using Gas Chromatography-Olfactometry, Odor Activity Value and Feller’s Additive Model

A total of 99, 96 and 98 volatile aroma compounds were identified in three kinds of soy sauce aroma type Xi Baijiu, namely, Xijiulan, Xijiuyinxiangguizhou and Xijiuyinzhi by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-flame photometric detection (GC-FPD), respectively, each including 12 sulfur-containing compounds. As determined by gas chromatography-olfactometry (GC-O), ethyl hexanoate (OAVs of 1720–1992), ethyl butanoate (OAVs of 1401–1523), ethyl octanoate (OAVs of 218–327), ethyl 3-methylbutanoate (OAVs of 835–966), 2-butylfuran (OAVs of 464–719), ethyl 2-methylpropanoate (OAVs of 146–342), 3-hydroxy-2-butanone (OAVs of 90–117), butanoic acid (OAVs of 71–79), 2-methyl-3-furanethiol (OAVs of 33–72), butanol (OAVs of 19–37), ethyl phenylacetate (OAVs of 90–91), hexanal (OAVs of 29–33), 2-methylpropionic acid (OAVs of 13–33), phenylacetaldehyde (OAVs of 16–35) and furfuryl alcohol (OAVs of 7–13) exhibited much higher odor activity values (OAVs) and aroma intensities (AIs) than the other compounds, which suggested that these aroma compounds were the main characteristic aroma compounds of Xi Baijiu. The correlation between the key aroma compounds and sensory attributes was further verified and explained by aroma recombination combined with partial least squares regression (PLSR). Finally, the perceptual interactions between five sulfur compounds and six esters in Xijiuyinxiangguizhou Baijiu were studied using Feller’s additive model to verify the accuracy of aroma identification of Xi Baijiu. The results showed that propanethiol, dimethyl trisulfide, 2-methyl-3-furanethiol, 3-mercaptohexyl acetate and 3-mercaptohexanol all enhanced the aroma of ethyl hexanoate, but enhanced or masked the aroma of the other five esters. The experimental data partly explained the interaction mechanism between aroma compounds, which would be helpful to improve the aroma quality of soy sauce aroma type Xi Baijiu through directional operation.