INTERACTION OF SUCROSE ESTER WITH CASEIN MICELLES AS CHARACTERIZED BYSIZE-EXCLUSION CHROMATOGRAPHY

Size-exclusion chromatography was used to investigate the interaction of sucrose ester P-1670, composed of 70% pure palmitic acid monoester, with native milk proteins as they are present in skim milk. Addition of sucrose ester to fresh raw skim milk or to casein micelles that had been isolated by chromatography of fresh raw skim milk without coolin g resulted in a small decrease in the elution volume and an increase i n the light scattering of the micelle fraction, indicating an increase in micelle size. In the skim milk sample, the elution volume of whey proteins also decreased slightly. Similar resolution of casein micelle s and whey proteins was obtained with tandem glycerylpropyl controlled -pore glass columns containing beads of mean pore diameters of 52 and 286 nm and with Sephacryl S-400. Analysis of micellar fractions by SDS -PAGE showed that the distribution of individual caseins in the micell es was not affected by sucrose ester. Quantitative determination of su crose ester using the periodate reaction confirmed the binding of the surfactant by casein micelles.