The physicochemical and sensory properties of rice prepared with different types of were examined. These large-scale rice cookers used gas, electricity and induction heating as the energy sources, and rice prepared with a normal gas rice cooker for family use was used as the reference sample.
A difference in the overall preference among the rice samples prepared with different cookers was apparent with the low-price Tsugaru roman variety. According to the curve for increasing temperature, there was no difference in the time to reach boiling point between the gas cooker and the induction heated cooker. Both cookers maintained over 98°C for more than 20 minutes which is needed to gelatinize the starch in rice. In contrast, the time taken to reach boiling point with the electric rice cooker was too long, and the degree of gelatinization of the starch in the upper layers of the rice was insufficient.
These results for large-scale cooking of rice indicate that an induction heated cooker should be used when electricity is the energy source, because the curve for increasing temperature is equivalent to that for a gas rice cooker. It was confirmed that the temperature history plays a key role in rice cooking.