Molecular characterization of corn starch using an aqueous HPSEC-MALLS- RI system under various dissolution and analytical conditions

SangGuan You, Seung Taik Lim

Research output: Contribution to journalArticle

91 Citations (Scopus)

Abstract

Molecular characteristics based on absolute weight-average molecular weight (M(w)) and z-average radius of gyration (R(g)) of normal corn starch were analyzed by high-performance size-exclusion chromatography (HPSEC) attached to multiangle laser-light scattering (MALLS) and refractive index (RI) detectors under different starch dissolution and analytical conditions. Autoclaving (121°C, 20 min) or microwave heating (35 sec) provided better HPSEC recovery and higher M(w)) for starch molecules than simple dissolution in hot water. The M(w)) for the autoclaved corn amylopectin and amylose fractions separated with a TSK G5,000 column at 60°C were 201 x 106 and 3.3 x 106, respectively. The specific volume for gyration (SV(g)) calculated from M(w)) and R(g)) could be used for the comparison of molecular compactness which was inversely related to the degree of branching. The SV(g)) values of amylopectin and amylose fractions in the chromatogram (TSK G5,000, autoclaved for 20 min) were 0.092 and 0.529, respectively. But a portion (20-30%) of large amylopectin molecules did not pass the injection membrane filter (3.0 μm) and the SEC column, resulting in incomplete recovery. The unfiltered portion varied according to the dissolution treatment. Homogenization (7,000 rpm, 5 or 10 min) of the starch solution improved the recovery of the amylopectin fraction, but significantly increased the M(w)) of the amylose fraction (17 x 106). Sonication for 5 min degraded starch molecules. For accurate analysis of a native starch using an aqueous SEC, the starch should be fully dissolved with proper treatment such as autoclaving or microwaving, and the column should be improved for full recovery of large amylopectin molecules.

Original languageEnglish
Pages (from-to)303-308
Number of pages6
JournalCereal Chemistry
Volume77
Issue number3
Publication statusPublished - 2000 May 1

    Fingerprint

ASJC Scopus subject areas

  • Food Science
  • Chemistry (miscellaneous)

Cite this