Surface Tension of Whey and Whey Derivatives

The surface tension of various whole wheys, solutions of component whey proteins, UF fractions, and the effect of heating on the surface tensions of these solutions were determined using the Wilhemy plate method. The mean surface tension of three commercial cottage cheese wheys, a commercial cheddar cheese whey, and a laboratory rennet whey was found to be 41.7 -+ 1.2 dyne/ cm (25C) and did not vary significantly with the type of whey despite differences in both pH and protein content. The surface tensions of aqueous solutions of individual pure protein fractions of whey (serum albumin, 13-1actoglobulin, a-lactalbumin, and gammaglobulins), in concentrations approximating normal whey contents, were significantly different and greater than for the whole wheys.