Correlation between moisture content of milled rice and Texture of cooked rice as evaluated by sensory test

Abstract

Rice (Oryza sativa L.) holds a high place among the world‘s top agricultural products for its economic and social importance. The prices of milled rice vary by the moisture contents of the rice while the retail prices paid by consumers depend upon the rice eating quality. The correlation between the moisture content of milled rice and the texture of cooked rice as evaluated by sensory tests is the main topic of this research. Five types of Thai rice from the rice quality improvement plant (C.P. Rice Co., Ltd.) were used in the study. The moisture contents of the five types of milled rice were measured with a rice moisture tester, while the texture of cooked rice was evaluated by a trained sensory panel of five females and five males. The 10 member panelists evaluated the cooked rice on the scale of 1 to 5 along the four texture indices of hardness, stickiness, adhesiveness and dryness. It is found that texture of cooked rice is unaffected by the moisture content as the coefficients of determination (R2) range from 0.163 to 0.187. However, the correlations between pairs of the four texture indices are found to be very high with R2 ranging from 0.935 to 0.970. The study shows any one index value (e.g., dryness) can be substituted in the linear equations containing such an index value (i.e., dryness) as a component to determine another (second) texture index value. The second index value is subsequently substituted in any linear equations with it as a component to determine the third index value. The procedure is repeated with the third value for the fourth index value. The practice could certainly reduce the time usually required of the rice quality improvement plant for rice quality inspection.