Cereal Chem. 70:226-230   |  VIEW ARTICLE

Determining the Degree of Gelatinization in Parboiled Rice: Comparison of a Subjective and an Objective Method.

W. E. Marshall, J. I. Wadsworth, L. R. Verma, and L. Velupillai. Copyright 1993 by the American Association of Cereal Chemists, Inc. 

Lemont and Tebonnet long-grain rice samples were parboiled either conventionally or by microwave to different degrees of starch gelatinization. The degree of gelatinization was determined by an objective method (differential scanning calorimetry) and by a subjective rice-grading method that yielded the percentage of translucent kernels in a given sample of parboiled rice. A linear correlation was found between the two methods for bot h varieties, which suggested that the grading procedure could be used to estimate the degree of gelatinization once a calibration curve was established. In addition, the degree of gelatinization, as determined by differential scanning calorimetry, was compared with head rice yield. The relationship between the two variables was nonlinear, and maximum head rice yield for both Lemont and Tebonnet was achieved when the starch was about 40% gelatinized. Our results indicate that extensive starch gelatinization (extensive parboiling) is not necessary to obtain maximum head rice yields.