Effect of Addition of Glutathione-Enriched Inactive Dry Yeast at Different Stages of Brewing on the Quality of Pear Wine

The present study was conducted in order to investigate the effects of adding different concentrations of glutathione-enriched inactive dry yeast (g-IDY) at different stages of brewing on the quality of pear wine. Wine was prepared from Korla fragrant pears. g-IDY was added at 10, 20 and 30 mg/L before alcoholic fermentation, malolactic fermentation or aging. After aging for two months, the contents of total and individual phenols, antioxidant activity, organic acid contents, aroma components and sensory evaluation of pear wine were analyzed. The results showed that adding g-IDY before alcoholic fermentation or aging significantly increased the content of total phenols and antioxidant capacity and decreased the color index of pear wine (P < 0.05). Besides, adding g-IDY increased the contents of malic acid, lactic acid and citric acid as well as total the content of flavor substances in pear wine. Adding g-IDY before alcohol fermentation or aging was beneficial to the formation of aromatic compounds and contributed to reducing the generation of some undesirable gas, but it led to the generation of more H₂S. Together, these findings showed that pear wine prepared with the addition of 20 mg/L of g-IDY before alcoholic fermentation showed the best quality, with total phenol content of 282 mg/L, total flavor substance content of 13453.22 mg/L and sensory evaluation score of 88.7 out of 100 points.