RELATIONSHIPS BETWEEN PHYSICOCHEMICAL PRO PERTIES OF NONGLUTINOUS RICE AND DEGREE OF EXPANSION OF RICE CRACKER

Rice has been used as an ingredient for making rice crackers in Japan. The quality of rice as a material for cracker was evaluated mainly by the degree of expansion. However, not much has been known about the c omponent of rice to relate the degree of expansion of rice cracker. So , relationships between physicochemical properties of non-glutinous ri ces and the degree of expansion of rice crackers were investigated usi ng eight varieties which differed in amylose content (15.8-31.0%) of r ice starch and protein content (6.11-9.32%) of milled rice. The degree of expansion of the rice crackers was negatively correlated with eith er the amylose content ranging from 21.3 to 31.0% or the protein conte nt ranging from 7.4 to 9.32%. The amylose content had a greater influe nce on the degree of expansion of the rice crackers than the protein c ontent. Starch contents of the milled rices decreased with an increase in those protein content. SDS-PAGE of the milled rice proteins showed similar patterns. The acid-solubility (0.25 N HCl, 55-degrees-C) of t he dried rice cakes, which was correlated with those degree of gelatin ization, showed high correlation with either the degree of expansion o f the rice crackers (r = 0.977*) or the amylose content (r = - 0.851* ). From these results, it was concluded that the degree of expansion of rice crackers was affected by the starch content of milled rices an d by the amylose content of rice starches which related to the degree of gelatinization.