Effect of Annealing Temperature on Gelatinization of Rice Starch Suspension As Studied by Rheologica! and Thermal Measurements

摘要

The effect of annealing temperature(T_a)on the Theological behavior of 10 wt % rice starch suspension was investigated by the dynamic viscoelasticity,the differential scanning calorimetry(DSC),and the amount of leached out amylose and the swelling ratio of starch suspension.The Theological behaviors of the annealed samples are classified into three types in terms of T_a:T_(a1),48 and 55 deg C,which are much lower than the gelatinization temperature,T_(gel)(=62 deg C);T_(a2),58,60,and 62 deg C,which are almost the same as T_(gel);and TT_(a3),65,68,70,and 73 deg C,which are much higher than T_(gel).For the samples annealed at T_(a2),the onset temperature of the storage and the loss moduli,G and G",increased with increasing T_a,and & and G"in the temperature range from 65 to 90 deg C gradually increased though smaller than those for the nonannealed sample,the control.This can be understood by the partial gelatinization;i.e.,the leached out amylose prevents further amylose from leaching out.The Theological property of the samples annealed at T_(a1)is not so different from that of the control,and the samples annealed at T_(a3)are almost gelatinized.The Theological behavior of starch suspension can be controlled by T_a.