Determination and comparison of flavor (retronasal) threshold values of 19 flavor compounds in Baijiu

Nineteen compounds, including ten esters, six acids, and three alcohols, were characterized and considered as significant tastants and aromas in Baijiu (Chinese Liquor). The flavor (retronasal) threshold values (FTVs) of these 19 compounds were determined by the 10 samples test method in hydroalcoholic solutions (46% v/v in ethanol). The FTVs of the compounds were calculated based on the best estimate threshold method. All the FTVs determined by the professional Chinese Baijiu tasters were lower than those by the nonprofessional tasters. For instance, the detection (2.31 mg/kg) and recognition (11.74 mg/kg) values of ethyl hexanoate determined by the nonprofessional group were higher than the respectively corresponding values 0.44 and 3.80 mg/kg determined by the professional group. All of the odor activity values (OAVs) of ethyl valerate (OAV: 1176.00 to 2321.17), ethyl octanoate (OAV: 6841.20 to 7851.60), and 1-butanol (OAV: 26.78 to 39.72) in Gujinggong Baijiu were more than 10-fold larger than their dose-over-threshold values (DoTs), for which the DoTs of ethyl valerate, ethyl octanoate, and 1-butanol were 92.84 to 183.25, 180.03 to 206.62, 1.18 to 1.75, respectively. On the contrary, the OAVs of ethyl heptanoate (OAV: 3.60 to 5.70) and isoamyl alcohol (OAV: 1.18 to 1.57) were lower than their corresponding DoTs at 152.62 to 241.63 and 12.26 to 16.41. The results demonstrated that it is necessary to consider and compare their DoTs and OAVs simultaneously on evaluating the contribution of flavor compounds in Baijiu. PRACTICAL APPLICATION: Sensory evaluation of threshold values of various flavor compounds could be significantly affected by their existing matrix. Most of the published results of the flavor threshold value of compounds were determined from the matrix such as beer, whiskey, red wine, rather than Chinese Baijiu. The results of this work not only could provide valuable information for flavor studies of Chinese Baijiu but also give useful information for the Baijiu industry to quality control.