RESEARCH-SCALE DRYING OF ROUGH RICE USING SILICA GEL

After harvest, most rough rice research samples are dried using ambient air, the temperature and relative humidity of which oscillates. Fluctuations in environmental conditions produce variation in the final moisture contents (MCs) of samples, yielding inconsistent functional properties. The goal of this study was to develop an alternative method for drying small rough rice samples using silica gel that would be capable of yielding accurate and precise final MCs while maintaining grain quality. Drying experiments incorporated a combination of 1- and 5-g moisture-permeable packets of silica gel, mixed with rough rice samples in plastic bags. The average adsorptive capacity of the packets in closed rough rice samples was established as 25% to 27% (i.e., 0.25- to 0.27-g water / 1-g silica gel). A desired final MC (12.5%) was achieved for silica-gel-dried rice samples within four to five days, and the milling quality of samples dried to 12.5% MC, expressed as head rice yield, was not significantly different from that of control-dried samples.