Microwave Radiations Replacement Instead of Steam to Paddy Parboiling

The effect of using microwaves instead of steaming in parboiling step on mechnial properties of two paddy variety such as breakage strength and healthy rice yield were studied. Paddy samples were soaked in hot water at 50, 60 and 70°C for two hours and then exposed to microwave radiation for 15, 30, 45, 60, 75 and 90 seconds at the output power of 800 Watts. Sample were divided into two categories, one steamed at atmospheric pressure for 15 minutes and another was not. Finally, all the samples were dried at 35 °C. An increasing trend for breakage strength and healthy rice yield (for both paddy varieties) was observed when microwave exposure duration was increased. This increase was significantly different in treatments with microwave duration greater than 30 s as compared to control. The highest kernel bending strength and healthy rice yield in 90 s microwave treatment and soaking temperature of 70 ° C for Fajr and Lanjan varieties  were 24.7 MPa and 70.7%, and 20.8 MPa and 75.5%, respectively. There was no significant difference between breakage strength and healthy rice yield of steamed samples for 15 minutes and non-steamed microwave treatment for both varieties. According to these results, the impact of microwave on parboiling process was acceptable and can be replaced by steaming.