Publication no. C-2000-0411-03R |  VIEW ARTICLE

Molecular Structure and Some Physicochemical Properties of High-Amylose Barley Starches.

Yasushi Yoshimoto (1), Jyunko Tashiro (2), Tadahiro Takenouchi (3), and Yasuhito Takeda (2,4). (1) United Graduated School of Agricultural Sciences, Kagoshima University, 1-21-4, Korimoto, Kagoshima 890-0065, Japan. (2) Department of Biochemical Science and Technology, Faculty of Agriculture, Kagoshima, University 1-21-4, Korimoto, Kagoshima 890-0065, Japan. (3) Takenouchi Barley Processing Inc., 4-12-4, Nanei, Kagoshima 891-0122, Japan. (4) Corresponding author. E-mail: <takeda@chem.agri.kagoshima-u.ac.jp> Phone/Fax: +81-99-285-8641. Cereal Chem. 77(3):279-285. Accepted January 12, 2000. Copyright 2000 American Association of Cereal Chemists, Inc.

The molecular structure and some physicochemical properties of starches from two high-amylose cultivars of barley, high-amylose Glacier A (HAG-A) and N (HAG-N), were examined and compared with those of a normal cultivar, Normal Glacier (NG). The true amylose contents of HAG-A, HAG-N, and NG were 41.0, 33.4, and 23.0%, respectively. Iodine affinities before and after defatting of starch, and thermograms of differential scanning calorimetry, indicated that HAG-A and HAG-N starches had a higher proportion of amylose-lipid complex than did NG starch. The amylopectins from HAG-A and HAG-N were similar to NG amylopectin in average chain length (18-19), beta-amylolysis limit (beta-AL 56-57%), number-average degrees of polymerization (DP(n) 6,000-7,500) and chain length distribution. Very long chains (1-2%) were found in amylopectins from all cultivars. HAG-A amylopectin had a larger amount of phosphorus (214 ppm) than the others. The amyloses from HAG-A and HAG-N resembled NG amylose in DP(n) (950-1,080) and beta-AL (70-74%). However, HAG-A and HAG-N had a larger number of chains per molecule (NC 2.4-2.7) than NG amylose (1.8) and contained the branched amylose with a higher NC (9.5-10.6) than that of NG amylose (5.8), although molar fractions of the branched amylose (15-20%) were similar.