Comparison of Size-Exclusion Chromatography and Flow Field-Flow Fractionation for Separation of Whey Proteins

Whey protein (WP) is a mixture of proteins, and is of high nutritional values. WP has become an important source of functional ingredients in various health-promoting foods. In this study, size-exclusion chromatography (SEC) and asymmetrical flow field-flow fractionation (AsFIFFF) were used for separation and analysis of whey proteins. It was found that a lab-prepared WP from raw milk is mostly of beta-lactoglobulin with small amount of higher molecular weight components, while a commercial whey protein isolate (WPI) powder contains relatively larger amount of components other than beta-lactoglobulin, including IgG and protein aggregates. Results suggest that AsFIFFF provides higher resolution for the major whey proteins than SEC in their normal operation conditions. AsFIFFF could differentiate the BSA and Albumin, despite a small difference in their molecular weights, and also was able to separate much smaller amount of aggregates from monomers. It is noted that SEC was able to show the presence of low molecular weight components other than the major whey proteins in the WP samples, which AsFIFFF could not show, probably due to the partial loss of those low molecular weight species through the membrane.