Difference of higher fatty acids and their ethyl esters in the distillation and aging of strong-flavor Baijiu

In order to understand the distillation rules of higher fatty acids and their ethyl esters in the distillation and aging process of strong-flavor (Nongxiangxing) Baijiu, and the effect of palmitic acid on Baijiu flavor was explored, the higher fatty acids and their ethyl esters in the distillation and aging process was detected by headspace solid-phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS). The results showed that the higher fatty acids contents were positively correlated with the distillation process, especially in the late distillation period. The contents of high fatty acid ethyl ester decreased first and then increased. Linoleic acid, stearic acid, palmitic acid and its ethyl ester and ethyl laurate were identified as the key markers to distinguish strong-flavor Baijiu with different aging years. During the aging, the contents of linoleic acid, stearic acid and ethyl palmitate decreased significantly in 8-year aged liquor, indicating that spontaneous esterification and ester volatilization co-acted. In addition, palmitic acid (50 mg/L) inhibited the volatilization of ethyl caproate by 30%, thus affecting Baijiu flavor.