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A Comparative Study on Pasting and Hydration Properties of Native Rice Starches and Their Mixtures

Four rice starches were isolated from waxy and nonwaxy rice cultivars collected from different places in China. Individual rice starches were examined, along with their corresponding mixtures in different ratios, in terms of pasting and hydration properties. Analysis by micro-viscoamylography (MVAG) showed that waxy rice starch and its blends had higher peak viscosity (PV), breakdown (BD), and setback (SB) than the remaining starches and mixtures. Apparent amylose content (AC) was 16.95–29.85% in nonwaxy individual rice starches and 13.69–25.07% in rice starch blends. Incorporating waxy rice starch (25%) significantly decreased the AC. AC correlated negatively with swelling power (SP) (r = -0.925, P < 0.01). SP exhibited nonlinear relationship (r² = 0.8204) with water solubility (WS) and both increased with temperature. The correlation showed that WS is also an index of starch characteristics and the granules rigidity affected the granule swelling potential. The results show that turbidity of gelatinized starch suspensions stored at 4 ± 0.5°C generally increased during storage up to five days.