(523f) Apple juice chemistry and cider fermentation: Phenolic and nitrogen composition influence fermentation rate and cider aroma

The phenolic and nitrogen composition of apple cultivars used for cider making are highly variable, with concentration ranges typically exceeding those previously evaluated in beverage fermentation research. Heritage, or traditional, cider apples are often valued for their relatively high concentration of tannins (phenolic compounds) and/or acids, which impart desirable sensory characteristics of tartness, bitterness, and astringency to cider. Most cider fermentation practices do not account for the potential effects of high concentrations of phenolic compounds on fermentation outcomes. The objective of this study was to determine the impact of three phenolic compounds: ferulic acid, p-coumaric acid, and chlorogenic acid—at concentrations reported in apples—and their interactive effects with yeast assimilable nitrogen (YAN) on cider fermentation kinetics and cider aroma. High concentrations of ferulic acid (300mg/L) resulted in lower fermentation rate and incomplete fermentation, and these negative effects could be partially remediated through addition of YAN (100mg/L and 200 mg/L), a common cider making intervention. A sensory sorting task showed that changes in pre-fermentation p-coumaric acid and ferulic acid concentrations influenced aroma, while chlorogenic acid did not, and that these effects were significantly different among the two yeast strains evaluated (W15 and EC 1118). This work demonstrates the complex and interactive effects of fruit chemistry on cider fermentation outcomes, and cautions against broad extrapolation of beverage fermentation management practices across diverse matrices.