Physicochemical Properties of Rice Flour Suspension Treated by Ultrahigh Hydrostatic Pressure

This study investigated the physicochemical properties of rice flour suspensions under ultrahigh hydrostatic pressure (UHP) treatment. Rice flour suspensions were subjected to 200, 400, and 600 MPa of pressure for 10 min, and heat treatment was used as a control. Proximate characteristics of different rice cultivar were analyzed to amylose, damage starch content, and particle size. Changes in physicochemical properties of rice flour suspensions according to UHP treatment were analyzed to microscopic structure, iodine reaction, α-amylase hydrolysis rate, and resistant starch content. Microscopic structural analyses showed that the structures of the rice flours were altered under both heat and 600 MPa treatment conditions. Water absorption rates were highest under heat treatment (467.53–554.85%), followed by 600 MPa treatment (269.55–334.57%). Iodine reaction values increased with increasing applied pressure. α-Amylase hydrolysis rates and resistant starch contents were highest under heat treatment and increased with increasing applied pressure. Based on these results, 600 MPa treatment of rice flour suspensions was shown to be comparable to heat treatment; as a result, the development of the new rice processing method with different physicochemical properties is expected from rice cultivars treated under UHP processing methods.