With its excellent foam building properties, gelatine can also be used to incorporate air into multi-phase emulsions through whipping or gas injection – from marshmallows and mousse desserts to cheese preparations. Gelatine decreases the surface tension of the water, facilitating foaming. Within the foam, the gelatine binds the water during the gelling process and surrounds the fat globules with a thin film. As such, it also stabilizes the foam. Large amounts of air are retained in the product, and different bubble sizes mean that a range of textures can be produced, from creamy to fluffy. Thanks to gelatine’s gelling and stabilizing properties, product texture is maintained, even during lengthy periods of storage.
In the case of marshmallows or aerated chews, gelatine prevents the recrystallization of sucrose. The ability to form and stabilize foams comes from the surface properties of gelatine: they are based on the fact that the gelatine side chains have charged groups and that certain parts of the collagen sequence contain either hydrophilic or hydrophobic amino acids. Both tend to migrate towards surfaces reducing the surface tension of aqueous solutions.