Isomalto/malto-polysaccharide structure in relation to the structural properties of starch substrates

P.H. van der Zaal, H.A. Schols, J.H. Bitter, P.L. Buwalda*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

18 Citations (Scopus)


Isomalto/malto-polysaccharides (IMMPs) are soluble dietary fibres produced by the enzymatic modification of starch with 4,6-α-glucanotransferase (GTFB). The structure, size, and linkage distribution of these IMMPs has remained largely unknown, since most structural information has been based on indirect measurements such as total α-(1→6) content, iodine staining and GTFB hydrolytic activity. This study provides a deeper understanding of IMMP structure in relation to its respective starch substrate, by combining preparative fractionation with linkage compositition analysis. IMMPs were produced from a variety of amylose-rich and amylose-free starches. The extent of modification was investigated per IMMP molecular weight (Mw)-fraction, distinguishing between linear α-(1→6) linkages introduced by GTFB and starch's native α-(1→4,6) branching points. It emerged that the amount of α-(1→6) linkages was consistently higher in IMMP low Mw-fractions and that GTFB activity was limited by native α-(1→4,6) linkages. The presence of amylose turned out to be a prerequisite for the incorporation of linear α-(1→6) linkages in amylopectin.
Original languageEnglish
Pages (from-to)179-186
JournalCarbohydrate Polymers
Early online date23 Nov 2017
Publication statusPublished - Apr 2018


  • Enzymatic modification
  • Glucanotransferase
  • Linkage analysis
  • Preparative fractionation
  • Starch
  • α-glucan


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