Pre-drying Effect and Quality Change of Rough Rice under Hot Air-Assisted Radio Frequency Disinfestation Treatment

Abstract.Abstract. Highlights HA-RF disinfestation treatment had better pre-drying effect of rough rice than that of HA treatment Highest moisture loss (8.7%) was obtained for samples with highest IMC (39.6% d.b.) Initial moisture content (IMC) correlated negatively with milling quality of rough rice HA-RF can be used as a pre-drying method to partially reduce the moisture content Hot air-assisted radio frequency (HA-RF) is an environmentally friendly disinfestation method, which can completely control the insects and meanwhile maintain quality of rough rice. In this study, the pre-drying effect of HA-RF disinfestation treatment of rough rice with different initial moisture contents (IMCs) (16.7%, 24.8%, 34.7%, and 39.6% d.b.) was investigated along with associated quality change. HA-RF treatments had better pre-drying effect of rough rice with various IMCs than that of Hot Air (HA) treatment and larger electrode gap obtained lower moisture removal. IMCs of rough rice also influenced the moisture removal for HA-RF treatments, and the corresponding moisture loss were 4.3%, 5.3%, 6.1%, and 8.7% for the treated rough rice with IMC of 16.7%, 24.8%, 34.7%, and 39.6%, respectively. More quality loss was observed for the rough rice with higher IMC, especially for broken rate, fissure, and water uptake ratio. HA-RF treatment had no influences on total phenolic acids, protein, and fat contents, but amylose and vitamin E contents were affected. None milled rice treated by HA-RF had an obvious decrease in the lightness (L*) except for the samples with highest IMC (39.6%). RF disinfestation treatment can be used as a pre-drying method to partially reduce the moisture content (MC) of rough rice.