Depletion interaction of casein micelles and an exocellular polysaccharide

Casein micelles become mutually attractive when an exocellular polysacchari de produced by Lactococcus lactis subsp. cremoris NIZO B40 (hereafter calle d EPS) is added to skim milk, The attraction can be explained as a depletio n interaction between the casein micelles induced by the nonadsorbing EPS. We used three scattering techniques (small-angle neutron scattering, turbid ity measurements, and dynamic light scattering) to measure the attraction. In order to connect the theory of depletion interaction with experiment, we calculated structure factors of hard spheres interacting by a depletion pa ir potential. Theoretical predictions and all the experiments showed that c asein micelles became more attractive upon increasing the EPS concentration . [S1063-651X(99)11307-2].