Physicochemical Properties of Starches in Japonica Rices of Differenct Amylose Content
2008
Song, J. (National Institute of Crop Science, RDA, Suwon, Republic of Korea), E-mail: [email protected] | Kim, J.H. (National Institute of Crop Science, RDA, Suwon, Republic of Korea) | Kim, D.S. (National Institute of Crop Science, RDA, Suwon, Republic of Korea) | Lee, C.K. (National Institute of Crop Science, RDA, Suwon, Republic of Korea) | Youn, J.T. (National Institute of Crop Science, RDA, Suwon, Republic of Korea) | Kim, S.L. (National Institute of Crop Science, RDA, Suwon, Republic of Korea) | Suh, S.J. (National Institute of Crop Science, RDA, Suwon, Republic of Korea)
This study was performed to find out starch properties of rice grains in three varieties with different amylose content, Ilpumbyeo (non-waxy), Goami2 (high amylose), and Hwasunchalbyeo (waxy rice). There was no difference among physico-chemical characteristics of rice grains, but Goami 2 showed 2~3 folds higher crude fat (1.36%) than Ilpumbyeo. Pasting properties of RVA showed the highest values of maximum viscosity, breakdown, and final viscosity in Ilpumbyeo. A similar chain length distribution of amylopectin was found in Ilpumbyeo and Hwasunchalbyeo, indicating that DP 12 had the highest distribution. Goami 2 had the highest distribution in DP 14, and showed the lower percent (14.1%) than other rice cultivars. Thermal properties of DSC showed that the values of Tc and Tp of Hwasunchalbyeo were similar to Ilpumbyeo, whereas a slightly higher Tc was observed. The absorbtion enthalpy was also the highest (11.1 mJ/mg) in Hwasunchalbyeo. Goami 2 showed higher To, but the lowest enthalpy (6.52 mJ/mg) compared to Ilpumbyeo (7.92 mJ/mg). Retrogradation properties, which were measured with the gelatinized rice sample used for DSC, and stored in 4℃ during 6 days, indicated that retrogradation absorbtion peak was the first peak at 52.6~55.2℃, and the second peak above 95℃. Retrogradation enthalpy of Goami 2 was the highest value (5.12 mJ/mg).
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