Moisture Sorption Characteristics and Mathematical Models of Rapeseed(Brassica napus)

The moisture sorption characteristics of rapeseed(Brassica napus) affect the storage quality of the crop and the techniques used in harvesting and storage. To provide a technical basis for the harvesting, storage, and management of rapeseed, this paper experimentally studied the moisture sorption characteristics of rapeseed at 0~30 ℃ and relative humidity of 32%~38%, and compared the applicability of seven mathematical models in the moisture sorption process of rapeseeds. The results showed that temperature and relative humidity were the main factors affecting the moisture sorption of rapeseed. With increasing temperature, the time needed for sorption equilibrium decreased, and with increasing relative humidity the equilibrium moisture content and time needed for sorption equilibrium increased. The net isosteric heat of rapeseed sorption exponentially decreased with increasing equilibrium moisture content. The Peleg model was considered to be the best mathematical model in describing the moisture sorption characteristics of rapeseed, with a correlation coefficient of 0.999, Chi-square value of 0.154, and root mean square error of 0.160. With increasing temperature, the critical relative humidity of rapeseed increased, and it is therefore considered that the critical relative humidity could be effectively decreased by decreasing the storage temperature. With the increase of equilibrium moisture content, the net isosteric heat of sorption of rapeseed exponentially decreased.