Foam Stability of Mucin - Caseinate Mixtures: Relevance to Oral Processing

This work studies saliva foam, and the effect of in vitro orally-processed model foods on this foamy state. It reaches an estimation on the volume fraction of air trapped as bubbles in the saliva of healthy young volunteers, a value close to 0.3. So air bubbles and foam state might be intrinsic colloidal properties of saliva, with implications on its physiological and physicochemical definition and role. It then studies the capacity of mucin to stabilize model saliva, and the role of food protein (here sodium caseinate) to influence this foaming and the resulting foam stability during oral processing in in vitro systems. Synergistic effects are observed between mucin and caseinate in foams in terms of their foaming capacity and foaming stability. These are discussed in relation to their water-air dynamic interfacial tension, while the bubbles are observed with confocal microscopy. The effects of replacement of mucin with caseinate, hence the relevant transitions in interfacial composition, are studied in high internal gas volume fraction foams, with sodium caseinate producing relatively thicker foams, and mucin bringing about higher long-term stability. The above are brought together and discussed in relation to the temporal evolution of foam during the oral processing of foods.

Automated summary

This study explores the formation of saliva foam and the influence of simulated foods on the foamy state. Researchers found that air bubbles and foam state in saliva may be intrinsic colloidal properties, impacting its physiological and physicochemical definition and role. The synergistic effects between mucin and food protein in foams, as well as their stability, are discussed in relation to water-air dynamic interfacial tension and confocal microscopy observations. Additionally, the study examines the replacement of mucin with caseinate in high internal gas volume fraction foams, with sodium caseinate producing thicker foams and mucin contributing to higher long-term stability. These findings are discussed in the context of the temporal evolution of foam during oral processing of foods.