Hydrogen sulphide production during cider fermentation is moderated by pre‐fermentation methionine addition
Yeast assimilable nitrogen (YAN) concentration and composition impact hydrogen sulphide (H2S) production and fermentation kinetics during wine fermentation, but this phenomenon has not been extensively studied in cider fermentation. Our hypothesis was that H2S production during cider fermentation could be decreased through pre‐fermentation modification of concentrations of individual amino acids. Apple juice (53 mg L−1 YAN) was supplemented with asparagine, arginine, methionine or ammonium and fermented with EC1118 and UCD522 yeast strains. No difference in H2S production among fermentations was observed with addition of asparagine, arginine or ammonium. Methionine addition of 5 mg L−1 decreased H2S production by yeast strain EC1118 at 53 mg L−1 YAN. With 153 mg L−1 initial YAN, only methionine addition of 50 mg L−1 decreased H2S production, and no tested methionine rates decreased H2S production with 253 mg L−1 initial YAN. Supplementation to 153 mg L−1 YAN resulted in increased H2S production at all methionine concentrations tested. Sensory differences in aroma were detected in samples supplemented with ammonium and methionine, and these differences were correlated with observed differences in H2S production. Our results indicate that supplementing cider fermentations with methionine leads to lower H2S formation, especially in apple juice containing low YAN.