Importance of insoluble amylose as a determinant of rice quality

Thirty‐two varieties of rice, belonging to various classes and characteristics, were studied for their textural and physicochemical properties. The varieties could be divided into five groups depending on their total and hot water‐insoluble amylose contents. It was found that the textural properties of the samples (stickiness and consistency of cooked rice and viscogram characteristics) could not be explained on the basis of the total amylose content alone, but they correlated well with the insoluble amylose content. As the insoluble amylose increased, the consistency and the setback increased, and the stickiness and breakdown decreased. The alkali degradation type of rice, and the equilibrium moisture content attained by it after soaking in water, also seemed to have an important relationship with its quality. Neither the protein content nor the gelatinisation temperature, or its various manifestations, seemed to have any relationship to the other quality characteristics studied.