Processing Conditions and Milling Yield in Parboiling of Rice

Abstract

Rate of absorption of water by paddy (rough rice) increases with. the temperature, but is
\nrelatively low below the gelatinization point; beyond this point, the grain absorbs water
\nrapidly, preferentially on its surface layers, leading to early bursting and leaching. Hence
\nfor best efficiency, soaking for parboiling should be done slightly below the gelatinization
\npoint, or, more conveniently, by storting at 70° to 75° C. and allowing natural cooling.
\nMilling quality of parboiled paddy depends on severity of heat treatment during parboil·
\ning and conditions of drying; the more severe the heat treatment, the better it is able to
\nwithstand adverse drying. Insufficient sooking leads to increased breakage. Simple
\nsoaking of paddy at or above 70 0 C. also improves milling quality. Rate of hydration
\nof paddy as well as improvement in its milling yield by parboiling shows varietal difference.