Changes in Microbial Counts, Enzyme Activity and Quality of Foxtail Millet Takju Treated with High Hydrostatic Pressure during Storage

摘要

Foxtail Millet Takju was treated with heat (65°C/30 min) (HT) or high hydrostatic pressure (27°C/400 MPa/10 min) (PT), and changes in microbial count, enzyme activity, and quality were determined during 30-day storage at 10 and 25°C. Total viablecellcount remained constant, while lactic acid bacteria and yeast were not detected in HT and PT Takjus. Relative activities of a-amylase in PT Takju significantly increased by 169.7% at 3 days storage, then decreased to 137.7 and 68.7% at 10 and 25°C,respectively, at 30 days. Relative activities of glucoamylase in HT Takju showed reversible change, and were 36.5 and 54.3% at 10 and 25°C, respectively, at 30 days storage. Activities in PT Takju increased with storage period, 158.2% at 30 days storageat 10°C. Titratable acidity in untreated Takju increased, while those in HT and PT Takjus remained almost constant during 30 days storage. Reducing sugar content in untreated Takju showed no change, while that in HT Takju increased gradually, reaching2.9% at 30 days, whereas that in PT increased sharply after 3 days, reaching 4.8% at 30 days. Sensory evaluation showed sourness and bitterness were low, and sweetness and overall acceptance were high in PT Takju after 30 days storage at 10°C.