Modelling of rheological behaviour in starch-lipid systems

Abstract

Starches are essential components of many formulated food systems. Interactions of corn, wheat and waxy maize starch suspensions with triglycerides of different saturation degree were analysed; a monoglyceride was also used as lipid phase. The rheological behaviour of the formulations was analysed by the transient shear stress curves (τ vs. time) obtained with a rotational viscometer. The power law and the Bird-Leider models satisfactorily fitted the experimental results, and visco-elastic parameters including time constants were obtained. Swelling capacity and leaching of amylose from the starch granules, with and without lipid addition, were measured after heating at 75 °C and 90 °C. Wheat starch granules were not affected by the addition of triglycerides either at 75 °C or at 90 °C. Triglycerides increased the swelling values of corn starch granules at both temperatures, while the monoglyceride decreased the swelling and the leaching of amylose. The waxy maize starch systems exhibited the greatest values of swelling capacity, and were not affected by addition of different lipids to the water phase. Pastes with high swelling power exhibited high viscosities and low b (visco-elasticity) values. This relationship was analysed considering amylose-monoglyceride complex formation, amylose/amylopectin ratio in corn, wheat and waxy maize starches and saturation degree of the triglycerides. ©1996 Academic Press Limited.