Radio frequency treatment improved the slowly digestive characteristics of rice flour

Reducing starch digestibility can be beneficial to control the increasing of postprandial blood glucose and reduce the risk of diabetes, obesity, and other related chronic diseases. In this study, the structure, digestibility and physicochemical properties of rice flour under radio frequency (RF) treatment was investigated. The structural properties of rice flour were characterized by the X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy and particle size analyzer. The results showed that RF treatment caused the aggregation of starch granules, resulting in the increase of particle size. The relative crystallinity and the short-range order of rice flour were reduced following RF treatment. In vitro digestibility results showed that the resistant starch content of indica, japonica and waxy rice flour (IRF, JRF and WRF) increased from 39.04% to 42.02%, 39.95%–45.12% and 36.26%–43.61% after RF treatment, respectively. Moreover, RF treatment reduced the peak viscosity and breakdown of IRF and JRF, whereas enhanced them in WRF. After RF treatment, the G′ and G″ of all samples increased, while the tan δ displayed an opposite trend. These results suggest that RF treatment has the potential to modify rice flour for extending its application range in food industries.