Relationship between Molecular Structure of Rice Amylopectin and Texture of Cooked Rice

쌀의 아밀로펙틴 분자구조와 밥의 텍스쳐

  • Kang, Kil-Jin (Research Center for New Bio-Materials in Agriculture, Seoul National University) ;
  • Kim, Kwan (Department of Food Science and Technology, Chonnam National University) ;
  • Kim, Sung-Kon (Department of Food Science and Nutrition, Dankook University)
  • 강길진 (서울대학교 농업생물신소재연구센터) ;
  • 김관 (전남대학교 식품공학과) ;
  • 김성곤 (단국대학교 식품영양학과)
  • Published : 1995.02.01

Abstract

The relationship betwwen the molecular structure of amylopectin and the texture of cooked rice was investigated using Korean rice [3 varieties of Japonica type and 3 varieties of Tongil type(Japonica-Indica breeding type)]. The molecular structure of rice amylopectin was polymodal and distributed A chain of $\overline{DP}$ 12.4, short B chain of $\overline{DP}$ 20.6, B chain of $\overline{DP}$ 26.3, long B chain of $\overline{DP}$ 45 and super long chain of above $\overline{DP}$ 55. The super long chain of amylopectin was composed of long linear chain with poorly branched chain. Also, the super long chain of amylopectin showed positive correlated with average chain length, inherent viscosity and ${\beta}-amyloysis$ limit$({\%})$, but negative correlated with ${\lambda}max$ of iodine reaction of amylopectin. The structural properties of amylopectin in Japonica type were different from those of amylopectin in Tongil type. In relationship between molecular structure of amylopectin and texture of cooked rice, the average chain length, inherent viscosity, ${\beta}-amyloysis$ limit and super long chain of amylopectin was showed a positive correlation with hardness, but a negative correlation with adhesiveness of cooked rice. The long chain of rice amylopectin is the less, the eating quality of cooled rice was the better. These results suggest that the molecular structure of rice amylopectin could be responsible for the texture of cooked rice.

Keywords

rice;amylopectin;${\beta}-limit$ dextrin;molecular structure;texture of cooked rice;super long chain