A Rapid Immunoturbidimetric Method for Whey Proteins in Nonfat Dry Milk and Buttermilk

An immunoturbidimetric assay, using antibodies to whole bovine whey, was developed for the rapid screening of whey proteins in nonfat dry milk and buttermilk. Milk samples are heat-treated prior to analysis to denature the whey proteins for a more uniform response to antibodies. Of the whey proteins tested, the assay is most sensitive to bovine serum albumin and the least sensitive to β-lactoglobulin. Precision of the method is about 4% coefficient of variation with a minimum detectable level of 3% whey protein concentrate added to nonfat dry milk. Results are compared with electrophoretic analysis of whey proteins and high performance size exclusion chromatography of the glycomacropeptide from rennet whey.