Polymerization model for prediction of heat-induced protein denaturation and viscosity changes in milk

A bicomponent polymerization model for heat-induced protein denaturation and viscosity changes in milk is presented. The model recognizes denaturation kinetics of β-lactoglobulin (β-lg) and the association between denatured β-lg and casein micelles. The aim of the study was to develop a mathematical model based on physical and chemical fundamentals for prediction of the rheology of milk products during thermal processes. The model reproduces both the degrees of denaturation of β-lg and the viscosity change of skim milk heated at temperatures between 80 and 120 °C very well. In contrast to the volume fraction model of Snoeren, the polymerization model accounts for higher viscosities of milk heated at a higher temperature at the same denaturation degree of β-lg. This confirms that, in addition to heat load, heating rate and temperature contribute to the rheological properties of dairy products. The model developed will be a basis for future research in describing the relation between process variables and the functional properties of milk products.