The x-ray diffraction intensities of rice starch and its fractions and the gelatinization and pasting characteristics of the starch were studied. The results obtained from blends of two rice starches with amylose contents ranging from 13.7 to 32.8% indicate that amylose content affects the degree of crystallinity of granular starch. Further, the intensities of five characteristic diffraction peaks of the starch were consistently correlated with its gelatinization and pasting characteristics. The CA type x-ray diffraction patterns of rice starch showed no appreciable differences in line intensities among varieties. However, when these intensities were considered in the light of concentration dependence with respect to amylose, significant differences were revealed which could be correlated with the gelatinization and pasting characteristics of starch. Amyloses from seven rice varieties showed different crystalline orders. These differences seemed to account for the unpredictability of the pasting characteristics of the starch of certain varieties, as reported by many investigators.
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Lugay et al. (1965) studied this question.