Small-angle neutron scattering of aggregated whey protein colloids with anexocellular polysaccharide

We have investigated the scattering properties of mixtures of aggregated-wh ey-protein colloid (AWC) particles and an exocellular polysaccharide (EPS) from a lactic acid bacterium. Exceeding a certain concentration leads to a phase separation, which can be explained by an effective depletion attracti on between the AWCs due to non-adsorbing EPS. The measured scattering inten sity of a AWC/EPS mixture shows that the structure factor of the AWC partic les increases at low wave vectors with increasing EPS concentration. The me asurements can be described qualitatively in terms of the structure factor, calculated using integral theory including an expression for the depletion interaction potential.