Effect of reduced glutathione on the quality characteristics of apple wine during alcoholic fermentation

To investigate the effect of reduced glutathione (GSH) on the quality characteristics of apple wine, 10, 20 and 30 mg/L of GSH were added to apple juice before alcoholic fermentation. Meanwhile, apple wine fermented by Saccharomyces cerevisiae which had been pre-incubated with GSH (100 mg/L) was another experimental group. Mono-phenols, GSH and oxidized glutathione (GSSG) were determined by HPLC. Aroma compounds were analysed by GC-MS. Further, E-nose was applied to monitor the odor. After fermentation, GSH content was the same in all of the samples. However, for the apple wine with GSH addition, GSSG content increased significantly. Notably, GSH could reduce the color index, protect chlorogenic acid and phloretin, decrease the content of epicatechin and catechin as well as change the profile of aroma compounds (higher levels of 2-methyl-1-propanol, 3-methyl-1-butanol, ethyl benzoate, linalool, etc.). GSH may be used for flavor enhancement and quality improvement of apple wine.