Effect of sulphur dioxide concentration added at different processing stages on volatile composition of ciders

This study evaluated the effect of sulphur dioxide (SO2) added at different steps in the process on the volatile composition contributing to the fruity aroma of cider. Potassium metabisulphite was added (150 and 300mg/L) at three processing steps (a) crushed apple, (b) apple must and (c) final product. The SO2 added to the crushed apple either maintained or increased the fermentation rate, whereas the addition to the apple must slowed the fermentation rate. The addition of 300mg/L of potassium metabisulphite to Golden Delicious apple must inhibited fermentation. The losses of volatile compounds varied from 23 to 46% and from 33 to 97% in all of the treatments with 150 and 300mg/L of potassium metabisulphite, respectively. 3-Methyl-1-butanol, acetaldehyde and ethyl ethanoate corresponded to >85% of the volatile compounds in the cider; 3-methyl-1-butanol was not affected by the sulphur dioxide. Acetaldehyde showed the greatest reduction (>80%) with the addition of sulphur dioxide and ethyl ethanoate was reduced when the compound was added to the crushed apple and apple must. All of the interactions between the apple variety, the stage of SO2 addition and the concentration of SO2 showed significant negative impact on volatile compounds. (c) 2018 The Institute of Brewing & Distilling