Brewing of glucuronic acid-enriched apple cider with enhanced antioxidant activities through the co-fermentation of yeast ( and ) and bacteria ().

Co-fermentation using yeast ( and ) and the bacteria () as starters isolated from spontaneous sourdough was conducted for the brewing of glucuronic acid (GlcA)-enriched apple cider. The concentration of GlcA in the apple cider co-fermented for 14 d with commercial and was 37.7 ± 1.7 mg/mL while a concentration of 62.8 ± 3.1 mg/mL was recorded for fermentation with and , which was higher than the corresponding single yeast fermentation. The co-fermented apple cider revealed higher 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of 171.67 ± 0.79 µg trolox equivalents (TE)/mL using and , compared to the control (143.89 ± 7.07 µg TE/mL) just using . Thus, the co-fermentation of and and and provided a new strategy for the development of GlcA-enriched apple cider with enhanced antioxidant capacity.