Changes in Quality of Spray-dried and Freeze-dried Takju Powder during Storage

Abstract

Spray-dried (SD) and freeze-dried (FD) takju powders were stored at 5, 15 and , and various quality characteristics such as moisture, amino nitrogen, color value, total viable cell count, total sugar, reducing sugar organic acid, and flavor compounds were measured for 50 days at 10-day intervals. After 50 days of storage, the moisture content was increased from an initial 6.64% to 7.24-7.38% in the SD powder, and from an initial 4.86 to 5.43-5.61% in the FD powder. pH, total acid content and total viable cell counts were slightly increased. Organic acid content was decreased in the SD powder from an initial 3,949.9 mg% to 805.9-922.3 mg%, and in the FD powder from an initial 5,171.5 mg% to 3,646.0-4,110.2 mg%. Amino nitrogen content was increased in the SD powder from an initial 1.2% to 1.9-2.2% and in the FD powder from an initial 1.9% to 2.2-2.5%. Total sugar and reducing sugar contents were increased in the SD powder from an initial 17.2% and 4.0% to 25.9-27.3% and 5.8-6.9%, and in the FD powder from an initial 19.1% and 5.2% to 29.2-30.2% and 8.3-8.8%, respectively. With increasing storage time, L and b values in the SD powder increased slowly, while L value in the FD powder tended to decrease and b value tended to increase. About 20 major volatile flavor components were identified in the SD and FD powders by GC-MS and all such component levels were decreased with increasing storage time.