The DHr value was the highest when frozen with the freezing
rate of 0.09 C/min, because a longer freezing time was needed and
more starch retrograded during the freezing process. However, the
DHr value was the lowest when cooked rice frozen with freezing
rate of 1.45 C/min, because of shorter freezing time and less starch
retrogradation. Moreover, the DHr values were not significantly
different between freezing rate of 0.26 and 0.53 C/min after 5
months of frozen storage. These results suggested that slow
freezing rates (0.09 C/min) increased the starch retrogradation
and higher freezing rates (1.45 C/min) retarded starch retrogradation
during frozen storage. These results were in agreement with
the research (Varavinit et al., 2002) which reported that quick
freezing retard retrogradation of starch gel, because the freezing
rate was too fast for the starch molecules to reorient to form the
precipitate or the hard gel.