Effect of adding five grains on volatile flavor substances of Kombucha milk wine based on GC-IMS

Kombucha milk wine was prepared with fresh milk as the raw material and fermented by Kombucha and yeast. Using Kombucha milk wine as the blank group (CK), and the Kombucha five grains milk wine prepared by mixed fermentation with five grains as the experimental group (WG), the volatile flavor substances were determined by gas chromatography-ion mobility spectrometry (GC-IMS) technology, and principal component analysis (PCA) and orthogonal partial least squares-discriminant analysis (OPLS-DA) were performed based on the results. The results showed that a total of 40 volatile flavor substances were detected in the two milk wine samples, including 10 alcohols, 16 esters, 5 ketones, 5 aldehydes, 2 hydrocarbons, 1 heterocyclic compound, and 1 terpene compound. The proportion of ester substances in the Kombucha milk wine (43.00%) was higher than that in the control (CK) (31.89%). PCA and OPLS-DA could effectively distinguish the two types of milk wine samples. Based on the relative odor activity value (ROAV) and variable importance in projection (VIP) value, 6 key volatile flavor substances (ROAV>1) and 14 differential volatile markers (VIP>1). To sum up, the malt flavor, herbal flavor, green flavor and apple flavor of the milk wine were increased by adding five grains fermentation.