Microstructure, mechanical properties, and starch digestibility of a cooked dough made with potato starch and wheat gluten

Abstract

Processed starch-protein foods may exhibit a variety of microstructures, hence different mechanical properties and starch digestibility but the relation between these parameters is yet to be resolved. This paper reports on the effect of three processing factors (extent of mixing, cooking temperature and cooking time) on the microstructure of a model dough system consisting of potato starch, wheat gluten and water, and the in vitro digestibility of starch in the matrix as well as the relationship between microstructure and starch digestibility. Samples subjected to a high mixing level showed lower rupture stress and rupture strain (decreased by 54% and 46%, respectively), a higher residual gelatinization enthalpy of starch (Delta H), and a higher amount of birefringent starch granules (increased by 25%). Additionally, at higher mixing level the in vitro starch digestibility resulted in 24% less slowly available glucose whereas the rapidly available glucose increased by 25%. These findings were related to the original microstructure of the dough examined by confocal scanning laser microscopy. (C) 2011 Elsevier Ltd. All tights reserved.