Physicochemical properties of floury-type rice upon soaking and heating

This study investigated and compared the physicochemical properties of pregelatinized floury-type rice (Baromi2) with those of normal rice (Samkwang). Both rice varieties were subjected to controlled soaking and heating to prepare pregelatinized rice flour. When heat treated without soaking, both varieties were partially gelatinized, whereas soaking led to 100% gelatinization as the starch granules fully collapsed. Additionally, as the soaking time increased, the hardness of the rice grains decreased significantly, and their lightness, yellowness, and whiteness decreased. As the gelatinization progressed, the particles agglomerated by the released amylose molecules became larger than those in the untreated samples, and the solubility and swelling power of the gelatinized samples increased by more than two-fold at room temperature. Water absorption before heat treatment was identified as a critical factor influencing heat transfer and structural transformation. This study suggests the usability of heat-treated floury-type rice as an intermediate material in the food industry.