Differential Scanning Calorimetry Quantification of Whey Proteins

Differential scanning calorimeters (DSC) are commonly used to determine the thermal properties of proteins. In this study, we evaluated if DSC thermograms could be used to quantify individual and mixed milk whey proteins by building linear models for each protein using purified known samples in increasing concentrations. Overall, we demonstrated that DSC can be used to quantify individual whey proteins with quantification limits between 0.17 and 0.49 mg/mL. This was highly repeatable between different samples and days (most relative standard deviations <3%). The determined quantification limits were low enough to quantify three of the milk proteins (β-LG, α-LA, IgG) at concentrations they would normally be found in milk. We were also able to use DSC to accurately quantify β-LG and α-LA simultaneously in mixed samples with each other and β-LG in mixed samples with all of the whey proteins. This data supports the use of DSC for the quantification of folded and purified protein samples.