Effect of cooking and soaking on physical, nutrient composition and sensory evaluation of indigenous and foreign rice varieties in Nigeria

The objective of this study is to ascertain the effect of cooking and soaking on the physical characteristics, nutrient composition and sensory evaluation of an indigenous “ofada” rice and a foreign “aroso” rice varieties in Nigeria.

The two rice varieties were freshly purchased in the raw state, soaked in water and cooked. The physical characteristics, such as length, width, weight, colour, purity, breakage, cooking time, dispersability and swelling capacity of the raw rice varieties were determined according to official methods. The raw, soaked and cooked rice varieties were oven‐dried at 60^○C for 4 h and milled to obtain a uniform surface area. The proximate composition and some minerals of the raw, soaked and cooked rice varieties and the sensory evaluation of the cooked rice were determined. Findings–The physical characteristics showed that “ofada” and “aroso” rice varieties were brown and creamy in colour, respectively. There were significant (p<0.01) differences in the purity, breakage, cooking time, swelling capacity and weight of the whole grain, but no difference in the length and width. The raw, cooked and soaked “ofada” rice contain more protein, fat, and fibre, than in “aroso” rice, but with no change in carbohydrate content. There were no significant (p>0.01) differences in the levels of minerals, Ca, Fe, Mg and P, in raw, cooked and soaked “ofada” and “aroso” rice. Sensory evaluation showed that cooked aroso rice was generally preferred, in terms of colour, aroma, taste, texture and overall acceptability.

The methods employed in this study are very simple and the two rice varieties are readily available, acceptable to local tastes and widely consumed in Nigeria. The local or indigenous “ofada” rice is compared favourably with a foreign and imported parboiled “aroso” rice. It is therefore possible for small scale and cottage industries to embark on commercial production and fortification of the local rice varieties in Nigeria.