4. Conclusions
The results suggest that microparticulation of whey protein enhanced the heat stability of whey-protein-stabilised emulsions. The greater stability of MP-WPC-stabilised emulsions to heating was attributed to the formation, through the microparticulation process, of protein particles that have fewer active sites available for further aggregation during secondary heat treatment (retorting). Therefore, the key factor determining the heat stability of the emulsions was the concentration of the undenatured protein in the serum phase. The study showed that MP-WPC allows the addition of much higher protein concentrations to emulsions because the proportion of undenatured protein is very low (∼25%).
The surface composition of the emulsion droplets was also altered by microparticulation, and was also thought to have an effect on heat stability. Even though the addition of salt decreased the heat stability of the MP-WPC-stabilised emulsions, there was no visible gelation or aggregation after retorting, suggesting the superior heat stability of microparticulated whey proteins. Thus, the addition of more protein into nutritional beverage formulations without heat-induced adverse effects is achievable with microparticulated whey protein.