Rheology and microstructure of custard model systems with cross-linked waxy maize starch

Foodstuffs are complex systems consisting of different chemical components that form the food matrix. The objective of this research was to study the influence of composition on the structure and rheology of some custard model systems with different dispersing phases (water or milk) and compare it with the structural and rheological behaviour of a custard dessert (COST 921 formulation). Samples were prepared with a Rapid Visco-Analyser, rheological measurements were carried out in a controlled stress rheometer and microstructure was assessed using Cryo-SEM. The results showed that the microstructure and the rheological behaviour of cross-linked starch dispersions depended mainly on starch, although the addition of sugar and the substitution of milk for water as dispersing phase, clearly modified these characteristics. Starch in water systems showed weak interactions, whereas sugar addition or/and the use of milk as a dispersing phase resulted in a denser network. These microstructural modifications were clearly reflected by the flow and viscoelastic behaviour of the analysed samples. Copyright (c) 2006 John Wiley & Sons, Ltd.