Comparative Analysis of the Physicochemical Qualities of Milled Rice Processed with Traditional and Improved Parboiling Methods in Nigeria

Abstract

A comparative study of the effects of traditional and improved parboiling methods on the physical and chemical properties of three commonly grown rice varieties in Nigeria was carried out. Samples of the rice varieties FARO 44, FARO 52 and FARO 60 were parboiled using the traditional and improved methods. The dry parboiled samples were milled in the laboratory and the physical and chemical qualities of the milled rice were determined. The traditional method of rice parboiling produced milled rice with lower head rice yield and higher percentage of broken rice. Traditional method of parboiling produced milled rice with higher grain hardness; 67.3N for FARO 44, 69.4N for FARO 52 and 63.8N for FARO 60. The grain colour improved with the use of the improved method of parboiling. The parboiling method did not significantly alter the classification of the amylose content of the rice grain. The amylose content for the three varieties was generally high at between 25% and 29% when processed by traditional method and between 27% and 34% when processed by improved method. The pasting temperature, however increased when FARO 44 and FARO 52 rice varieties were parboiled by improved method while a decrease was observed in FARO 60 rice variety when parboiled with improved method. A maximum increase of about 2.4% in the crude protein content was observed when the rice varieties were parboiled with improved method. The use of traditional method of rice parboiling should therefore be discouraged for the processing of rice especially, the three varieties used in this study in Nigeria.