Superheated steam pretreatment of rice flours: Gelatinization behavior and functional properties during thermal treatment

The effect of superheated steam pretreatment on the gelatinization behavior and functional properties of waxy and non-waxy rice flour were studied. The superheated steam-treated waxy rice flours and non-waxy rice flours showed significantly lower onset of gelatinization temperatures (58.8 and 56.1 °C, respectively) than that of their respective control. Water binding capacity, swelling power, solubility and particle size of rice flours were evaluated from 20 to 90 °C. Before the gelatinization temperature (<60 °C), the water binding capacity and swelling power were about 1.7 times higher for the superheated steam treated waxy rice flour and 1.4 times higher for the superheated steam treated non-waxy rice flour than those of their control. The superheated steam treated non-waxy rice flour had a significantly higher particle diameter (82 μm) than the other flours. The granules of superheated steam-treated flours were swollen more than the native flours granules due to partial gelatinization. Superheated steam may be a promising physical method for modification of specific properties of rice in terms of gelatinization behavior, granular structure and functional characteristics of rice flours.