In recent years, the ready-meals market has grown significantly
in developed or developing countries, and many ready to eat meals
including cooked rice have been developed .
Freshly cooked rice are soft, pliable and elastic, but when stored they
stale within a few hours and become tough and rigid. In less than 3
days the shelf-life of cooked rice presents a major problem and can
be costly to the producer, distributor, consumer and the country in
general. The short shelf-life of cooked rice, which is mainly due to
staling, i.e. starch retrogradation, increased hardness or decreased
adhesiveness, is a serious problem. Concerning the preservation
technologies applied to ready to eat meals, freezing has been
recognized as an excellent method of preserving the quality characteristics
of foods and extending their shelf-life.
Some of the recent studies have reported on the effects of
freezing on bread quality and staling properties. Rapid freezing resulted in a less structure changes and less
retrogradation of starch or starchy foods than slow freezing
. However, the rate of starch retrogradation is
influenced by the cooling rate before storage at temperatures for
frozen foods, rapid cooling rate contributed to higher rice starch
retrogradation (DHr) than slow cooling rate during storage. On the other hand, storage temperature
and time also have significant effects on the quality of starchy
foods. reported that the slight advantage of non cell u1ar
starchy product by rapid freezing was lost during storage,
and cooked rice hardness increased and stickiness decreased at
lower temperatures and longer storage. Retrogradation enthalpy of bread
increased during frozen storage , and the hardening rate of bread depended
on frozen storage time during aging . Based on the literatures cited above, freezing rate and storage
temperature and time have significant effects on the starch retrogradation
and textural properties of starchy foods.
However, the effects of storage temperatures, cooling methods and cooling rates
on the quality of cooked rice have been studied, less is known about the effects of freezing rate and
storage temperatures on the starch retrogradation and textural
properties of cooked rice. Therefore, the objective of the current
study was to examine the impacts of freezing rate and storage