Effect of Organic Acids Addition to Fermentation on the Brewing Characteristics of Soju Distilled from Rice

Han-Seok Choi*, Eu-Gene Kim, Ji-Eun Kang, Soo-Hwan Yeo, Seok-Tae Jeong, and Chan-Woo KimFermented Food Science Division, National Academy of Agricultural Science, RDAAbstract Following supplementation with organic acids (acetic, citric, and lactic acids), the pH of the alcohol mashchanged from 4.2 control to 3.73-3.97 supplemented, the acidity from 5.06 to 8.13-9.98, and the alcohol content from 17.8to 17.0-17.8%. Protease activity decreased owing to the pH change, and the total nitrogen content decreased by 13.1-36.9%following organic acid supplementation. Organic acid supplementation did not affect the distillation efficiency; however,thiobarbituric acid values in the crude distillate (40%) decreased 2.2-3.6 fold following supplementation with citric acid andlactic acid. The total isobutanol (B), isoamyl alcohol (A), and 1-propanol (P) contents in each soju (25%) supplementedwith organic acid were 1,041.47, 979.50, and 961.48 ppm, respectively, which were higher than those in the control soju(935.27 ppm). The A/P, A/B, and B/P ratios of soju were altered and the acetaldehyde content decreased followingsupplementation with the organic acid.Keywords: soju, organic acid, nuruk, distilled liquor, brewing