On the relation between the molecular mass distribution of gelatin and its ability to stabilize emulsions

The relation between the molecular mass distribution of gelatin and its effectiveness in stabilizing emulsions of dibutyl phthalate and dodecane in water have been investigated. The molecular mass distribution was determined using gel permeation chromatography. The ability of gelatin samples to stabilize emulsions was investigated by observing the coalescence of macroscopic oil droplets in a special device. The results show that all samples with a content of more than 30 wt.-% in the low-molecular mass range are good stabilizers, whereas the stabilizing ability is diminished drastically by decreasing the low molecular mass content below 30 wt.-%. Mechanisms for the stabilization and rupture of the thin water film between the oil droplets are discussed, especially in the case of gelatin adsorption layers at the film interfaces. A model is given for the qualitative explanation of the dependence of the stabilizing ability of gelatins on the molecular mass distribution.