DETERMINATION OF OPTIMUM CONDITIONS IN FLASH DRYING FOR HIGH MOISTURE ROUGH RICE.
2008
Saburi Halestani, Samad | Apruz, Mohammad | Rafiei, Nader | Kamran, Hadi | Mahdavi, Hossein
Paddy drying is one of the principle stages in rice production. The method of drying is chosen according to paddy initial moisture content. Recently high technologies rice combines which do both harvesting and threshing at the same time which and give fresh paddy with MC of 20-22%, have been imported to Iran. It is necessary to dry fresh paddy in minimum time with the best method. The aim of this study was to determine the best method of fresh paddy drying. The research was carried out in a CRD with to factors including: temperature (T1= 40 and T2=55 oC), paddy layer thickness (L1=20 and L2=40 cm) and method of drying (continues & non-continues). Fresh paddy prepared of local variety (Hashemi). All paddies were dried to the storage moisture content (14%) based on the different treatments, then keeping drying at 40 oC until the paddy moisture content reached to 8-9%. The result showed that the highest head rice (74.6%) was observed at 40 oC, paddy layer thickness of 20 cm with continues method. Increasing in air drying temperature or paddy layer thickness resulted in decreasing head rice yield. Head rice At 55 oC drying temperature and 40 cm paddy layer thickness were 46.3% and 57.8% in continuous and non-continuous methods respectively. Changing the paddy layer thickness to 40 cm resulted in head rice yield 66.4% and 59.3% in continuous and non-continuous methods respectively. Milling degree result showed high temperature, low layer thickness and continues, or low temperature, high paddy layer thickness in non-continues had positive effects on rice whiteness index. The percentage of cracked grain was not affected by treatment of drying conditions.
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