Phenolic compounds, antioxidant activity and color in the fermentation of mixed blueberry and grape juice with different yeasts

Fermentation of blueberry and grape mixed musts in a 1:1 ratio with 4 different yeast strains has been studied. In order to evaluate which yeasts maintain the highest content of phenolic compounds, color and antioxidant activity. The musts were fermented with four types of strains, of which three were commercial yeasts QA23, Elegance MP061, M05 Mead and one isolated from partially fermented musts of Pedro Ximenez, X5 (CECT131015). In addition to the use of these yeast strains, spontaneous fermentation with indigenous fruit yeasts was used as a control. First, it was shown that the use of yeast inocula reduced the fermentation time avoiding the latency phase where the yeast adapts to the fermentation medium of both fruits. Second, among the wines obtained, the control wine was the one losing the least total phenolic compounds and less antioxidant activity. However, wines obtained from fermentation with inoculum showed the least color loss and a higher content of anthocyanins and flavonols. In fact, the M05 Mead yeast obtained the lowest loss of color, total phenolic compounds, and antioxidant activity; and the highest concentration of anthocyanins and flavonols. Therefore, this yeast was the most appropriate for the winemaking of mixed blueberries and grapes musts.