EFFECT OF DEHYDRATION METHODS ON DIGESTED STARCH FRACTIONS OF RETROGRADED DEBRANCHED RICE STARCH.

The effect of dehydration methods on the fractions of rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) was studied. The rice starch suspension was gelatinized and debranched with pullulanase for 24 h. The debranched rice starch (DBRS) was subjected to aging for 48 h with time temperature cycling treatment with temperatures of 30 and 80°C. After aging, the DBRS was dehydrated using various dehydration conditions and methods: 10 and 24% solid with temperatures of 120 and 140°C for drum drying, 10% solid with inlet temperatures of 150 and 170°C and outlet temperatures of 90 and 110°C for spray drying, and 24% solid with 50°C for 10 h and 80°C for 8 h for hot air oven drying. The lower RS content and the higher RDS and SDS content were observed in all dehydration conditions as compared with the fresh sample before dehydration. The spray drying method showed the highest RS of 43%, the lowest RDS of 15% and SDS of 18%, and the melting temperature of 82-110°C, while the dehydration using the hot air oven and drum drying demonstrated the RS content of 39% and 36%, the SDS content of 20% and 21%, and the RDS content of 16% and 17%. The drum drying method exhibited an A+V type crystalline structure with the minimum relative crystallinity of 19% and the maximum melting temperature of 116-123°C, while that of the other dehydration methods illustrated the B+V type. [ABSTRACT FROM AUTHOR]