Abstract:In order to understand the differences in the contents of lactic acid and ethyl lactate isomers in baijiu (Chinese liquor) of different flavor types, a separation method for directly determining the lactic acid and ethyl lactate isomers in baijiu was established, and the content rules were analyzed. It was shown by the results that the enantiomers of lactic acid had a linear relationship within the range of 0.02 - 0.6 g/L; the enantiomers of ethyl lactate had a linear relationship within the range of 0.01 - 2.5 g/L. Significant differences existed in the optical rotation contents of lactic acid and ethyl lactate in baijiu of different flavor types. In Maotai-flavor baijiu, the contents of D-lactic acid and L-lactic acid were relatively high, with the average mass concentrations being 1.348 g/L and 0.440 g/L respectively. The average mass concentrations in Luzhou-flavor baijiu were 0.402 g/L and 0.244 g/L respectively, and those in Fen-flavor baijiu were 0.161 g/L and 0.042 g/L respectively. In Maotai-flavor baijiu, the contents of D-ethyl lactate and L-ethyl lactate were relatively high, with the average mass concentrations being 1.280 g/L and 0.283 g/L respectively. The average mass concentrations in Luzhou-flavor baijiu were 0.592 g/L and 0.352 g/L respectively, and those in Fen-flavor baijiu were 0.211 g/L and 0.038 g/L respectively. All in all, the method was simple to operate, with high precision and accuracy, and was applicable to the determination of the optical rotation of lactic acid and ethyl lactate in baijiu. The differences in the optical rotation contents of lactic acid and ethyl lactate in baijiu of different flavor types were clarified, providing data support for further exploring the flavor formation mechanism of baijiu.
