Molecular interactions, morphology and macroscopic properties of mixed protein-protein systems

Selective mixing of gel forming ingredients can be used to produce foods with a wide range of textural properties. Whereas protein/polysaccharide mixtures are widely studied, protein/protein mixtures are researched to a much lesser extent. Rheological and microstructural properties of different globular protein/gelatin mixed gels were investigated. The molecular interactions between these proteins were quantified in terms of their virial coefficient and used to explain microstructural and rheological changes during independent gelation of each of the proteins in the presence of the secondary protein. Results showed that only when analyzing mixed systems over a large range of length scales (molecular to macroscopic, nm to cm) one is able to explain properties observed on a macroscopic level, such as fracture properties or water holding. In mixtures of globular proteins (soy, whey) and gelatin both proteins were able to form continuous networks if triggered to gel.
The presence of the other, secondary protein allowed alteration of the gel properties (on micro and therefore macroscopic length scales) dependent on the size and interaction between proteins. The gained insights into mixed protein systems point out the possibilities how intentionally choosing proteins based on their size and interaction allows one to steer microstructure development during
gelation. This is interesting not just for research but also for the development of protein gels with desired texture and sensory properties.