Molecular breakdown of corn starch by thermal and mechanical effects

R.M. van den Einde, C. Akkermans, A.J. van der Goot, R.M. Boom

Research output: Contribution to journalArticleAcademicpeer-review

68 Citations (Scopus)

Abstract

The molecular weight reduction of corn starch at 30-43% moisture during thermal treatment at temperatures 90-160degreesC and during well-defined thermomechanical treatment at temperatures 90-140degreesC was investigated. Thermal treatment resulted, during the first 5 min in a decrease in molecular weight as measured by intrinsic viscosity, after which longer heating had no significant effect. Higher moisture contents and temperatures generally resulted in more breakdown, although the effect diminished at higher temperatures. The decrease in intrinsic viscosity during thermomechanical treatment at relatively low temperatures and moisture contents was shown to be only dependent on the maximal shear stress. At higher temperatures, thermomechanical breakdown could be split into a mechanical part depending on maximal shear stress and a thermal breakdown part, which was again time-dependent on the shorter time-scales only. Higher moisture content during thermomechanical treatment resulted in more thermal breakdown and lowered the shear stresses required for mechanical breakdown. Consequences for process design are discussed briefly. (C) 2004 Elsevier Ltd. All rights reserved.
Original languageEnglish
Pages (from-to)415-422
JournalCarbohydrate Polymers
Volume56
Issue number4
DOIs
Publication statusPublished - 2004

Keywords

  • twin-screw extrusion
  • waxy maize starch
  • weight degradation
  • amylopectin
  • depolymerization
  • fractions
  • rheology

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