On the role of the internal chain length distribution of amylopectins during retrogradation: Double helix lateral aggregation and slow digestibility

Laura Roman; Josephine Yee; Anna M R Hayes; Bruce R Hamaker; Eric Bertoft; Mario M Martinez

doi:10.1016/j.carbpol.2020.116633

On the role of the internal chain length distribution of amylopectins during retrogradation: Double helix lateral aggregation and slow digestibility

Carbohydr Polym. 2020 Oct 15:246:116633. doi: 10.1016/j.carbpol.2020.116633. Epub 2020 Jun 13.

Authors

Laura Roman¹, Josephine Yee¹, Anna M R Hayes², Bruce R Hamaker², Eric Bertoft², Mario M Martinez³

Affiliations

¹ School of Engineering, University of Guelph, 50 Stone Road East, Guelph, Ontario N1G 2W1, Canada.
² Whistler Center for Carbohydrate Research, Department of Food Science, Purdue University, 745 Agriculture Mall Drive, West Lafayette, IN 47907, USA.
³ School of Engineering, University of Guelph, 50 Stone Road East, Guelph, Ontario N1G 2W1, Canada; Department of Food Science, iFOOD Multidisciplinary Center, Aarhus University, Agro Food Park 48, Aarhus N, 8200, Denmark. Electronic address: mm@food.au.dk.

PMID: 32747268
DOI: 10.1016/j.carbpol.2020.116633

Abstract

A structure-digestion model is proposed to explain the formation of α-amylase-slowly digestible structures during amylopectin retrogradation. Maize and potato (normal and waxy) and banana starch (normal and purified amylopectin through alcohol precipitation), were analyzed for amylose ratio and size (HPSEC) and amylopectin unit- and internal-chain length distribution (HPAEC). Banana amylopectin (BA), like waxy potato (WP), exhibited a larger number of B3-chains, fewer BS- and B_fp-chains and lower S:L and BS:BL ratios than maize, categorizing BA structurally as type-4. WP exhibited a significantly greater tendency to form double helices (DSC and ¹³C-NMR) than BA, which was attributed to its higher internal chain length (ICL) and fewer DP6-12-chains. However, retrograded BA was remarkably more resistant to digestion than WP. Lower number of phosphorylated B-chains, more S- and B_fp-chains and shorter ICL, were suggested to result in α-amylase-slowly digestible structures through further lateral packing of double helices (suggested by thermo-rheology) in type-4 amylopectins.

Keywords: Amylopectin; Amylose; Banana; Chain length distribution; Glycemic response; Retrogradation; Starch.