Effects of intermittent drying on physicochemical and morphological quality of rice and endosperm of milled brown rice

The objective of this study was to evaluate the cumulative effects of intermittent drying in function of the number of cycles and exposure time of the grains to high temperatures in the dryer and its correlations with the physical, physicochemical and morphological quality of rice and brown rice. For drying rice, it is important to control the intermittence time and the air-drying temperature to minimize the effects of the process on grain quality. With an increase in the drying time, ruptures in brown rice endosperm and an increase in burned and chalky grains are observed. In addition, reductions in physicochemical composition and changes in the starch structure and crystallinity are also observed. The grouping of the treatments and the correlations of the qualitative variables indicate that a longer drying time has the most significant effect on rice quality. The physicochemical quality and the morphological structure of rice and brown rice are preserved when intermittent drying is carried out for 3 h, avoiding excessive heating (>39 °C) of the grain mass and thermal damage to the grain cell tissues and the physicochemical quality of rice.