Changes in antioxidant activities and volatile compounds of mixed berry juice through fermentation by lactic acid bacteria

The objectives of this study were to analyze antioxidant activities and identify volatile compounds in mixed berry juice after fermentation by lactic acid bacteria (LAB). Antioxidant activity of the mixed berry juice increased significantly from 209.57±2.93 to 268.30±1.75 μmol TE/g after 24 h of fermentation. After LAB fermentation, 34 volatile compounds were identified. Among them, three compounds—benzoic acid, benzaldehyde, and vitispirane—showed significant changes in their concentrations. Peak areas of benzoic acid and benzaldehyde, which are known to possess antioxidant activities, increased by 64 and 188%, respectively, after fermentation. However, the peak area of vitispirane, which is the most abundant terpene compound in berry juices, decreased by 92% after fermentation.