A Study on Drier Performance and Milling of Parboiled Rice in a Selected Auto Rice Mill

Abstract

This study addresses the performance of the drier and milling in connection with the processing of parboiled rice of variety BRRI-14 (Gazi) at a local auto rice mill located at Gopalpur, Mymensingh. The rice mill practices the cycle of pre- steaming, soaking and steaming for parboiling operation. The moisture content (17.5% w.b.) of the paddy increased to 29.7% (w.b.) after soaking and steaming. The materials were then dried to 14.6% (w.b.) moisture content in a continuous flow re-circulating type mechanical drier of capacity 11000 kg for about 7 hours. The average drying air temperature was 40.3°C. The efficiency of the drier was found to be 84.77%. The drying rate constant was 0.35 per hour. The average percentage of cracked or fissured rice kernels after drying was found to be 5.2. The rice mill used a rubber roll huller and three disc type polishers for milling operations. The milling recovery and head rice yield for mechanically dried paddy were 71.5% and 70% respectively while for sun dried paddy these were 68% and 65%, respectively.