Type and concentration of acid on solubility and molecular size of acid–methanol-treated rice starches differing in amylose content
2010
Chang, Yung-Ho | Lin, Jheng-Hua | Pan, Ciao-Ling
Rice starches differing in amylose content were treated in methanol with acid at 45 °C for 1 h, effects of acid type and concentration on the solubility and molecular size of starch were investigated. Significant differences were found in solubility and weight-average degree of polymerization (DP(w)) among starches treated with different acids at the equal normality. Starch treated with HCl had lower DP(w) than treated with H2SO4 or HNO3. The hydrogen-ion concentration in methanol was negatively correlated (p < 0.001) with the DP(w) of starch despite of type and concentration of acid used. The increment in degradation extent of waxy rice starch with increasing hydrogen-ion concentration in methanol was lower than that of non-waxy rice starch. Results indicate that the distinct deionization extent of acids in methanol influences the degradation of starch, and that the hydrogen-ion concentration can be used to monitor the degradation of rice starch during acid-treatment in methanol.
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