Water Absorption Behavior of Milled Parboiled Rice in Relationship with Variety and Some Basic Thermodynamic Properties of Steam

Abstract

The effect of variety and some basic thermodynamic properties of steam which include pressure and specific volume of steam on water absorption capacity of parboiled rice was studied. Four rice varieties, Faro 21, Faro 27, Faro 29 and Faro 35 were used for the experiment. An insulated electric paddy parboiler comprising a boiler and steamer was used to pre-treat the rice under established recommended conditions. The samples were then dried, milled and analyzed. The results showed that the rice treated with the first steam pressure of 1.0 x 104 N/m2, 1.148 m3/kg and 1.576 m3/kg levels of specific volume of steam absorbed more water cumulatively while the level of steam pressure of 5.5 x 104 N/m2, 1.290 m3/kg and 1.433 m3/kg levels of specific volume of steam recorded the least values. Among the rice varieties, Faro 29 was found to have 163.2 ml and 71.1 ml water absorption capacity at the highest and lowest cooking duration of 40 mins and 10 mins respectively. A regression equation which predicts cumulative water absorption capacity of rice at varying steam pressures and specific volumes of steam were also developed.