Pasting and rheological properties of starch from soft rice and two traditional rice varieties were analyzed. Soft rice starch was found to have a low pasting temperature of 67.2 °C, with a high system viscosity, including peak and trough viscosity. The storage modulus and loss modulus of soft rice starch were high and showed good viscoelasticity. The amylose content of soft rice starch was found to be 11.3%, classifying it was low amylose content type. Compared with japonica rice starch, soft rice starch had lower solubility but higher swelling power, gel consistency, and water binding capacity. The medium particle size and volume mean particle size of soft rice starch were the highest. The average molecular weight of soft rice starch was 5.4 × 107. The molecular density and proportion of short amylopectin side chains, with a range of 6-12, were the highest among all varieties tested. These findings provide a theoretical basis for the processing of soft rice starch and breeding of high-quality rice.
Keywords: Molecular density; Soft rice starch; Viscoelasticity.
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