The Ratio of Interlamellarly Fixed Water to Bulk Water Used as Quality Criterion in O/W Creams

Abstract

AbstractO/W creams with crystalline gel structures are supposed to be four phase systems. Their dominant structural elements are the hydrophilic and lipophilic gel phases. The hydrophilic gel phases have — depending on the hydrophilic character of their polar groups — a very strong swelling capacity. Further, a dynamic equilibrium is maintained between the water interlamellarly inserted into the hydrophilic gel phase and the bulk water phase. The latter is mainly fixed mechanically by the hydrophilic gel phase. — The lipophilic gel phase, however, which immobilize the dispersed phase, have no or only an extremely weak swelling capacity. By means of thermogravimetry (TG) a quantitative differentiation between water interlamellarly fixed in the hydrophilic gel phase and bulk water is possible. — It is concluded that the ratio of interlamellarly fixed water and bulk water is an important criterion for the properties of O/W creams and that TG can be suitably applied not only as in process control during product manufacturing but also as a useful tool in the development of O/W creams with a controlled water release. During physical ageing of O/W creams the ratio of interlamellarly fixed water and bulk water is shifted towards the bulk water phase.