Changes in the physical properties of frozen cooked rice depending on thermal insulation levels of packaging during freeze‐thaw

Frozen cooked rice, a common commercially available product, has become the food of convenience in different parts of the world. Frozen foods that are well made in factories often experience quality deterioration due to temperature fluctuation during distribution. This study aimed to evaluate the impact of repeated freeze‐thaw, which may occur during distribution, on the physical quality of frozen cooked rice. Additionally, the effect of the thermal insulation levels of the packaging on the quality change of frozen cooked rice as a result of repeated freeze‐thaw was analyzed. The repeated freeze‐thaw treatment of frozen cooked rice resulted in moisture loss, microstructure destruction, increase in hardness, increase in adhesiveness, decrease in the L*‐value, increase in the a*‐value, increase in the b*‐value, and increase in the ΔE‐value. In particular, the quality of frozen cooked rice quickly deteriorated in samples stored in packaging with low thermal insulation. On the contrary, the higher the thermal insulation of the packaging, the longer the changes in the physical properties of the frozen cooked rice were delayed. The findings of the present study show that the deterioration of quality induced by the repeated freeze‐thaw treatment of frozen cooked rice could be suppressed by thermal insulated packaging. Practical Application The present study indicates that thermal insulated packaging can be used for industrial packaging of frozen cooked rice, as it delays the quality deteriorating effects of repeated freeze‐thaw. This can help maintain the quality of frozen cooked rice and improve consumer satisfaction despite temperature fluctuations during distribution.