2021 年 32 巻 1 号 p. 23-30
We focused on three cooking methods of rice porridge that is the first solid food given to infants: "rice in a pot”, "using the rice porridge mode on a rice cooker”, and "cooked rice in a pot”. The findings revealed that the gelatinization degree of all sample was about 95%. "Using the rice porridge mode on a rice cooker” had the highest amount of amylose and reducing sugars in 1.0g of rice porridge liquid, which was consistent with the properties at the end of cooking. The amount of reducing sugars produced was highest in the "cooked rice in a pot” since it took a long time to reach the deactivation temperature of the starch degrading enzyme. However, the concentrations of reducing sugars, amylose and eluted solids in the rice porridge liquid were lowest because i) water was added to cooked rice, which has low water absorbability; ii) the amount of added water was higher than other methods; and iii) the heating time in pot cooking after adding water was shorter. Because the heating time at 90°C or higher of "cooked rice in a pot” is shorter than other methods, it had the hardest rice grains. As shown above, even though all the heating conditions used in the present study were designed to make "jyubai-gayu”, hardness and viscosity varied depending on heating conditions.