Impact of amylose content on starch retrogradation and texture of cooked milled rice during storage

Milled rice from 11 varieties, with amylose levels from 1.2 to 35.6% dry base, were collected to study the impacts of amylose content on starch retrogradation and textural properties of cooked rice during storage. The relationship between amylose content and different properties was determined using Pearson correlation. Starch retrogradation enthalpy (Delta H-r) of cooked rice was determined by differential scanning calorimetry. Delta H-r values were found to be positively correlated with amylose content (0.603 <= r <= 0.822, P < 0.01) during storage. Textural properties were determined by a Texture Analyser. The hardness of cooked rice showed a positive correlation with amylose content (0.706 <= r <= 0.866, P < 0.01) and a positive correlation with Delta H-r of cooked rice (r = 0.650, P < 0.01) during storage. The adhesiveness showed a negative correlation with amylose content (-0.929 <= r <= -0.678, P < 0.01) and a negative correlation with Delta H-r of cooked rice (r = -0.833, P < 0.01) during storage. Hardness showed a negative correlation with adhesiveness (r = -0.820, P < 0.01). These results indicated that amylose content has significant effects on starch retrogradation and textural properties of cooked rice. The cooked rice with high amylose content is easy to retrograde, the cooked rice with low amylose content retrograded slowly. Sarch retrogradation contributes to the changes of textural properties of cooked rice during storage. (C) 2009 Elsevier Ltd. All rights reserved.