LAUSR

Waxy rice which has been soaked in excessive water was cooked with hydrocolloid solutions, corresponding to hydrocolloid concentrations of 0.3, 0.5 and 0.7 g/100 g rice. Hydrocolloids studied were guar gum (GG), xanthan gum (XG) and sodium alginate (SA). The hydrocolloid-cooked rice and the control sample, cooked in water without any hydrocolloid, were determined for their starch retrogradation, texture, microstructure and in-vitro starch digestion rate. It was found that hydrocolloid-cooked rice exhibited more retrograded starch than the control, providing high melting enthalpies. Retrograded starch caused the increased hardness of the cooked rice during storage, while adhesiveness and springiness tended to decrease. Although, hydrocolloid-cooked rice retrograded more during storage, it showed a lower hardness than the control sample due to the phase separation of hydrocolloids. SEM images revealed that intact starch was completely gelatinized. The control sample provided denser microstructure than the hydrocolloidcooked samples. While air cells were observed in the hydrocolloid-cooked samples especially with XG. The hydrocolloid-cooked rice exhibited lower starch digestion rate than the control. SA provided the lowest starch digestion rate, followed by GG and XG respectively