SODIUM CASEINATE-STABILIZED EMULSIONS - FACTORS AFFECTING COVERAGE AND COMPOSITION OF SURFACE-PROTEINS

As the concentration of caseinate in sodium caseinate-stabilized emuls ions increased, the protein surface concentration increased. It platea ued at 1.36 +/- 0.05 mg/m(2) at a caseinate concentration between 2 an d 4% (w/w), but the surface protein concentration markedly increased a s caseinate concentration rose from 5 to 7.5%. At caseinate concentrat ion below 2%, beta-casein adsorbed at the surface of oil droplets in p reference to other caseins. Increasing the oil concentration from 10 t o 30% (w/w) decreased the surface protein concentration from 3.7 +/- 0 .3 to 1.4 +/- 0.04 mg/m(2), but further increases in oil concentration had much less effect. A decrease in surface protein concentration was observed as the homogenization pressure increased from 34 to 136 bar, but higher pressures had no further effect. beta-Casein was adsorbed preferentially at the droplet surface in emulsions homogenized at pres sures above 204 bar. Addition of calcium chloride to sodium caseinate solutions above 0.08% w/w resulted in formation of large casein partic les/aggregates which adsorbed on to the droplet surface causing higher surface protein concentration.