Grain quality and properties of starch and amylopectin of intermediate-and low-amylose indica rices
2011
Tuaño, A. P. P., Philippine Rice Research Inst., Los Baños, Pili Drive, College, Laguna 4031 (Philippines) | Umemoto, T. | Aoki, N., National Agricultural Center for Hokkaido Region, Soyohira, Sapporo 062-8555 (Japan). Rice Breeding and Quality Research Team | Nakamura, Y. | Sawada, T., Akita Prefectural Univ., Akita City 010-0195 (Japan). Faculty of Biological Resources | Juliano, B. O., Philippine Rice Research Inst. Los Baños, Pili Drive, College, Laguna 4031 (Philippines)
Selected intermediate-and low-apparent amylose content(AC) Philippine rices differing in alkali spreading value(index of starch gelatinization temperature, (GT) and cooked rice hardness were characterized for differential scanning calorimetry(DSC) measurement of gelatinization of granular starch, content of long-chain amylopectin and true amylase by high-performance size exclusion chromatography of debranched starch and amylopectin, amylopectin chain ratio(ACR) of sigma degree of polymerization(DP) 6-10/sigma DP 6-24 of debranched starch by capillary electrophoresis. The waxy gene alleles were mainly 17G and 20G for intermediate-AC samples and 17T and 20T for low-AC samples, regardless of GT. Long-chain amylopectin content was as predicted from apparent amylose content, and ACR was as predicted from GT by DSC and alkali spreading value. AC of milled rice was higher than that of debranched starch by size exclusion chromatography. Differences in long-chain amylopectin content cannot explain differences in cooked hardness among both AC types, and ACR alone cannot explain differences among intermediate AC types. The lower AC of Starch of intermediate-AC rice with intermediate GT compared with those of intermediate-AC rice with low GT probably contributed to its softer cooked rice. Increase in cooked hardness from staling was higher for high-and intermediate-GT samples, particularly in low-AC types.
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