The effect of pre-denatured whey proteins on the textural and micro-structural properties of model processed cheese spreads

Whey proteins (WP) were heated in a scraped-surface heat exchanger to produce products with different levels of denaturation. Model processed cheese spreads containing the WP were prepared. Rheological measurements showed that higher levels of denaturation in the WP produced softer (lower elastic modulus) cheeses. Temperature scans indicated that the cheeses prepared with high levels of native whey proteins did not melt (the elastic modulus was higher than the viscous modulus at all temperatures), whereas those prepared with high levels of denatured whey proteins melted on increasing the temperature. Microstructural examination of selected cheeses indicated that, when denatured whey proteins were used in processed cheeses, the whey proteins were incorporated as large aggregates dispersed within the cheese matrix. These aggregates did not contribute to, and may disrupt the structure of the cheese. When native whey proteins were used, they were incorporated into the cheese matrix, producing a denser network structure.