Analysis of bovine whey proteins in soybean dairy-like products by capillary electrophoresis

摘要

The simultaneous separation of bovine whey proteins [a-lactalbumin and b-lactoglobulin (A1B)] and soybean proteinsudwas performed, for the first time, by capillary electrophoresis. Different experimental conditions were tested. The mostudsuitable consisted of 0.050 M phosphate buffer (pH 8) with 1 M urea and 1.2 mg/ml methylhydroxyethylcellulose, UVuddetection at 280 nm, 15 kV applied voltage, and 308C temperature. Quantitation of bovine whey proteins in a commercialudpowdered soybean milk manufactured by adding bovine whey to its formulation was performed using the calibration methodudof the external standard. Direct injection of a solution of the powdered soybean milk only enabled quantitation ofuda-lactalbumin in the commercial sample. Detection of b-lactoglobulin (A1B) required acid precipitation of the solution ofudthe sample in order to concentrate bovine whey proteins in the supernatant prior to the analysis of this protein in the wheyudobtained. Since a-lactalbumin could also be quantitated from the injection of the whey, the simultaneous determination ofuda-lactalbumin and b-lactoglobulin (A1B) was possible upon acid precipitation of the powdered soybean milk solution.udDetection limits obtained were 14 mg/g sol. for a-lactalbumin and 52 mg/g sol. for b-lactoglobulin (A1B) which representudprotein concentrations about 60 mg/100 g sample for a-lactalbumin and 100 mg/100 g sample for b-lactoglobulin (A1B).ud 1999 Elsevier Science B.V. All rights reserved.