Cereal Chem 51:51 - 55.  |  VIEW ARTICLE
Influence of Rice Crystallinity on Cross-Linking.

M. N. Islam, J. E. Rutledge, and W. H. James. Copyright 1974 by the American Association of Cereal Chemists, Inc. 

The failure to cross-link starch in white rice by phosphorus oxychloride and sodium trimetaphosphate has been related to the inherent degree of crystallinity in the ungelatinized kernel. Parboiled rice, because of its larger amorphous domain as evidenced by X-ray diffraction, gave satisfactory response to phosphorus oxychloride and sodium trimetaphosphate. Comparison of the molecular weight, size, and shape of epichlorohydrin, phosphorus oxychloride, and sodium trimetaphosphate, considering the compact crystal lattice of white rice, indicates that epichlorohydrin would have the easiest access into the grain. Instability of phosphorus oxychloride in alkaline solution, and the stronger ether linkage formed by epichlorohydrin, may also contribute to the discrepancy in cross-linking of white rice.