Enzyme inactivation and quality preservation of sake by high-pressure carbonation at a moderate temperature

The effect of a high-pressure carbonation treatment on the change in quality of sake during storage was investigated. Measurements of the amino acidity and isovaleraldehyde content of carbonated sake (20 MPa pressure at 40, 45 and 50 degrees C for 7, 21 and 33 min, respectively) as well as of heat-treated sake (reaching temperature of 65 degrees C and immediately cooled) were almost unchanged during storage at 3 and 20 degrees C. Glucose in the sake subjected to these treatments was retained at an almost constant under the same storage conditions, except for the sake carbonated at 40 degrees C and stored at 20 degrees C. In contrast, the amino acidity, and glucose and isovaleraldehyde contents of non-pasteurized (fresh) sake increased during storage at both temperatures. The sake samples subjected to the carbonation treatment and heat treatment both gave better sensory scores than the fresh sake sample after 6 month of storage at 3 and 20 degrees C, especially at 3 degrees C for the flavor. These results suggest that the high-pressure carbonation treatment is an effective new technique for preserving the quality of sake.