1996 Volume 47 Issue 11 Pages 1099-1107
The Properties of frozen cooked rice thawed at room temperature were studied. The samples of rice used were of the Koshihikari variety from Niigata and Mie harvested in 1993. Three methods of cooking were used : A) The standard method involved soaking for 30 min at 20 °C, then vigorously boiling for 5 min and finally gently boiling for 15 min. B) The high-temperature soaking method involved soaking for 30 min at 60t, then vigorously boiling for 5 min and finally gently boiling for 15 min. C) The long-boiling method involved soaking for 30 min at 20 °C, then vigorously boiling for 20 min and finally gently boiling for 5 min.
The frozen and thawed cooked rice was unfavorably evaluated in comparison with normal rice just after cooking. The best evaluated samples of frozen-thawed cooked rice were those soaked at 60°C for 30 min (B), boiled for 20 min and then 5 min for Niigata Koshihikari (C), and soaked at 60°C for 30 min for Mie Koshihikari (B).
The moisture content of normal rice after cooking was the same as that of frozen and thawed cooked rice.
The increase in hardness of Niigata Koshihikari in the rheolometer test was slight with soaking at 60°C for 30 min (B), and with boiling for 20 min and then 5 min (C). The change of adhesiveness of Mie Koshihikari with soaking at 60t for 30 min (B) was small.
The histological changes of cooked rice after freezing and thawing were minor.
