Effects of Heating Conditions on Physicochemical Properties of Skim Milk Powder during Production Process

Abstract

To investigate the effects of production-related heat treatments on physicochemical properties of skim milk powder, four kinds of skim milk powder were prepared under different heating conditions. The degree of heating was expressed as the integrated caloric content added to the powders. The four skim milk powders were dispersed in water, and the physicochemical properties of them were compared. Solution turbidity increased with an increase in integrated caloric content, but the protein content in the supernatant decreased; the latter characteristic indicated that severe heating conditions resulted in aggregate formation of denatured whey protein molecules. The content of sulfhydryl groups and surface hydrophobicity of skim milk solutions were closely related to the heating conditions in the production process. SDS-PAGE analysis revealed that β-lactoglobulin and α-lactalbumin were main proteins involved in aggregate formation. The powder that had been treated with the most severe heating condition was found to be the most suitable for making bread.