Molecular characterization of wheat amylopectins by multiangle laser lightscattering analysis

Weight-average molecular weight (M-w) and chain length of eight amylopectin s isolated from one Australian, two United States, and five Korean wheats w ere measured using multiangle laser light scattering (MALLS) and refractive index (RI) detectors operated in a microbatch mode, and in a high-performa nce size-exclusion chromatography (HPSEC) mode. The M-w of amylopectins mea sured in the microbatch mode ranged from 29 x 10(6) to 349 x 10(6). Three a mylopectins (Geuru, Tapdong and WW) showed significantly high M-w values ov er 200 x 10(6). The M-w measured by HPSEC mode with MALLS-RI detectors (42 x 106 to 73 x 10(6)) were significantly less than those obtained in the mic robatch mode with exception of dark northern spring hard wheat (DNS) amylop ectin, indicating the possible variation of M-w by the analysis mode. Root- mean square of the radius of gyration (R-g) also was greater when the micro batch mode was used (122-340 vs. 95-116 nm). Chain length distributions of debranched amylopectins of different cultivars, measured by the HPSEC-MALLS -RI system, were similar. Weight average degrees of polymerization (DPw) of A, B-1, and larger B chains (B-greater than or equal to 2) had ranges of 1 3-22, 26-46, and 58-73, respectively, and mass ratios of A and B chains ran ged from 0.7 to 1.1.