The effect of rice aging on the freeze-thaw stability of rice flour gels

This study investigated the effect of aging rice on the freeze-thaw stability of rice flour gels since repeated freeze-thaw cycles can lead to reduced food quality. A rice grain cultivar called 'Khoa Dawk Mali 105' was aged for three different time periods, ranging from 0 to 12 months. Rice gels made from the aged rice were then freeze-thawed for up to 5 cycles. Repeated freeze-thaw cycles lead to an increase in syneresis values and hardness with increasing rice aging. Differential scanning calorimetry showed an increase in the enthalpy of melting of the amylose-lipid complex after 5 freeze-thaw cycles and an increase in peak gelatinization temperature and gelatinization enthalpy with longer rice aging. Moreover, aging length of the rice correlated significantly with a decrease in peak viscosity and breakdown but also an increase in final viscosity and setback. These results demonstrate that aging the rice reduced the freeze-thaw stability of the rice flour gels. (C) 2012 Elsevier Ltd. All rights reserved.