Effects of far-infrared radiation on the gelatinized rice starch granules

Abstract

A prototype far-infrared (FIR) dryer was developed to study the effects of far-infrared radiation on physicochemical properties changes of rice flour and energy consumption for gelatinization. A thin layer of rice flour was exposed to different FIR intensities (11.2, 8.5, and 7.8 kW m−2) and different time intervals (2–16 s). The degree of gelatinization, viscosity changes, color changes, acidity changes during storage, and energy consumption for gelatinization were measured. The degree of gelatinization, color changes, and viscosity increased with FIR intensity and exposure time. Gelatinized rice flour showed significantly (p < 0.05) lower acidity development compared to non-gelatinized flour during storage. The drying rate increased, and specific energy consumption decreased with increasing FIR intensity. It was found that optimum gelatinization can be achieved at 11.2 kW m−2 FIR intensity for 16 s. All these results confirm that FIR is an effective source of rice flour roasting.