Use of soybean isolate in coated foods: simulation study employing glass balls and substantiation with extruded products

Simulation studies on coating using glass balls as ideal solid and soy flour isolate dispersions of different concentrations (10-25%) and at different temperatures (20-50 degrees C) were conducted. A few coating parameters such as total uptake of dispersion, solid uptake, dimensionless uptake (DU) and uptake per unit area were determined. Further, the study was extended by using corn-soy extrudates in place of glass balls while using soy flour isolate dispersion of same concentrations and maintained temperature ranges. Rheological characteristics of the dispersions like flow behaviour index, consistency index, apparent viscosity and yield stress were determined to relate them with coating behaviour. The dispersions behaved like a non-Newtonian shear-thinning fluid and exhibited yield stress between 0.75 and 1.72 Pa. An increase in concentration of solids in the dispersion increased yield stress, consistency index and apparent viscosity while the flow behaviour index decreased from 0.67 and 0.39. Inter-relationships between various rheological and coating characteristics were determined; simulation studies on coating by employing glass balls can provide a good interrelation of vertical bar r vertical bar >= 0.88-0.99 that is comparable with vertical bar r vertical bar >= 0.69-0.99 (P <= 0.01) obtained with actual experimentation using corn-soy extrudates.