Study on crystalline, gelatinization and rheological properties of japonica rice flour as affected by starch fine structure.

ABSTRACT

Although many researches have investigated the effects of starch characteristics on its functional properties to evaluate rice quality, few studies were carried out the correlations between starch molecular structure and rice processing properties. In this study, eight varieties of japonica rice with similar content of protein and lipid and less variant content of amylose (12.12-18.19%) were elaborately selected. The result showed that crystalline and pasting parameters were mainly reliant on the differences in chain length distribution of amylopectin. Amylose content and chain length distribution, especially for average exterior chain length (ECL) and interior chain length (ICL) and their entanglement, showed significant correlation on rheological parameters. Swelling power of rice flour showed negative correlation with amylose content. Furthermore, in temperature-reduction process when the temperature is lower gelatinization temperature of amylopectin, the variation of loss modulus was affected by amylopectin. In addition, the PCA plot clearly revealed the interrelationship of all parameters.