Stability and texture of protein foams: A study by video image analysis

The foaming properties of four protein solutions were analysed. A video image camera was coupled to an instrument designed to study foam formation and stability. The textures of images were characterized by a mathematical procedure derived from the two-dimensional Haar transform (HT). Similarities and differences in foam textures were assessed by principal component analysis. Thus, foams were compared on the basis of their volumes, drainage rates and textural characteristics. It was possible to distinguish the different protein foams according to their textures and to differentiate between stable and unstable foams. Some relationships were noted between foam densities, drainage rates and textural appearances. Nevertheless, the texture of foams could not be deduced directly from their densities. Textural analysis is complementary to other methods of foam analysis.