RHEOLOGICAL CHARACTERIZATION OF CROSS-LINKED WAXY MAIZE STARCH SOLUTIONS UNDER LOW ACID ASEPTIC PROCESSING CONDITIONS USING TUBE VISCOMETRY TECHNIQUES

A rheological characterization of 1.82 and 2.72% (g dry starch/100g water) waxy maize starch solutions was performed at 121.1, 132.2, and 143.3°C using tube viscometry techniques. Dilatancy was observed in 22 out of 23 experiments and the flow behavior index increased with concentration and decreased with temperature. Rheological behavior was explained in terms of the rigidity and volume fraction of the swollen granules combined with small shear stresses in the fluid due to the high temperatures and low shear rates. Parameter correlation analysis showed a near correlation between rheological parameters with the flow behavior index being the dominant parameter. The effect of dilatancy on residence time and heat transfer in the aseptic processing of particulate and nonparticulate foods is discussed. Copyright © 1990, Wiley Blackwell. All rights reserved