High-amylose wheat starch: Structural basis for water absorption and pasting properties. (1st October 2020)

• Record Type: Journal Article
• Authors: Li, Caili; Dhital, Sushil; Gilbert, Robert G.; Gidley, Michael J.
• Is Part Of: Carbohydrate polymers. Volume 245(2020)
• Publication Date: 2020-10-01
• Subjects: High-amylose wheat flour -- High-amylose wheat starch -- Water absorption -- High-temperature RVA -- Farinograph; Polysaccharides -- Periodicals; Polysaccharides -- Periodicals; Polysaccharides -- Périodiques; Electronic journals; 547.78
• DOI: 10.1016/j.carbpol.2020.116557
• Languages: English
• ISSNs: 0144-8617

Abstract

Highlights: High amylose wheat starch (HAWS) has high water absorption but low pasting properties HAWS branches are longer for amylopectin but shorter for amylose than wildtype. Granule order is low for HAWS, contributing to high water absorption. Pasting of HAWS is much greater after heating to 140 °C than 95 °C. Flour components reduce final pasting viscosities but values similar for all amylose contents. Abstract: High-amylose wheat starch (HAWS) and flour (HAWF) have the potential to deliver food products with enhanced nutritional functionality, but structure/function relationships are not well understood. We report the structural bases for differences in water absorption and pasting properties for HAWS and HAWF (amylose contents 71–84 %) compared with wild-type (WTWS/WTWF). With higher amylose content, the proportion of longer amylopectin chains with DP > 25 increased. Both the degree of branching and the branch lengths of amylose were lower for HAWS than WTWS. Compared with WTWF, HAWF contained less total starch, more protein, had lower peak viscosity by high-temperature RVA, lower dough development time and stability time and higher water absorption by Farinograph. Water absorption by HAWS was ∼1.5 times greater than for WTWS, suggesting loose packing of polymers within HAWS granules. Consistent with this, crystallinity and birefringence of starch granules were lower in HAWS.