Effect of the size of perforated screen and blade-rotor clearance on the performance of Engleberg rice whitener

An experiment was conducted to study the effects of two engineering factors on the performance of Engleberg rice whitener as the most common machine for rice milling in the North of Iran. Three levels of the size of perforated screen (No. 22, 24 and 26) and three levels of the blade-rotor clearance (8, 10 and 12 mm) were considered for the experiment. Breakage percent and whiteness of milled rice and output rate of the machine were measured for milling of long grain paddy variety of Hashemi. It was concluded that as the size of perforated screen increased, amount of rice breakage and whiteness decreased at first and then did not change significantly. Amount of rice breakage and whiteness decreased with increasing the blade-rotor clearance. The output rate increased significantly with increasing blade-rotor clearance but no the effect of the size of perforated screen was significant on the output rate. A clearance of 10 mm and perforated screen No. 26 was the best combination for milling of Hashemi variety using Engleberg rice whitener.