|
|
DisplayTitle
Page Content
The Cinderella of starch structure: Amylose fine structure and functional properties of starch-containing foods
R. G. GILBERT (1), A. C. Wu (1), K. Wang (1), F. J. Warren (1), F. Vilaplana (2). (1) University of Queensland, Brisbane, QLD, Australia; (2) KTH Biotechnology, Stockholm, Sweden
There have been extensive investigations of the effects of amylose content and amylopectin fine structure (the chain-length distribution, CLD) in starch-containing materials on functional properties such as digestion rate. The CLD of amylose has been a neglected Cinderella in this regard. While amylopectin CLDs can be obtained with high accuracy using FACE, amylose branches are too long for this technique, which instead must be measured using size-exclusion chromatography (SEC, also termed GPC) following debranching with isoamylase. The resulting CLD must be corrected for band broadening. The amylose CLD always shows at least two features, possibly because of contributions from two or more enzymatic processes. Our recent data suggest that certain characteristics of this CLD significantly affect in vitro digestibility of cooked rice. Extensive new data for amylose fine structure from a wide range of plant species (including rice, sorghum, wheat and maize) and varieties within these species, together with in vitro digestibility rates for using food-like products obtained by cooking the flour. In vitro data on digestion to glucose are fitted with multi-step kinetics. For each of the two (and sometimes three) features apparent in the CLD, the data could be fitted both empirically (height and degree of polymerization for each peak) and with new theory [extending to amylose our earlier model on amylopectin]. Correlations between the fine-structure parameters and digestion rates suggest new tools for developing plants with nutritionally desirable digestibility.
View Presentation |
|
|
|
|
