Foam stabilization by two genetic variants of recombinant αs1-casein

In thin film balance experiments, low concentrations of RCB (0.05%) formed mobile interfaces that allowed for Gibbs-Marangoni flows and led to superior foam stability (t1/2: 1 h). At increased concentrations of RCB the Gibbs-Marangoni flows were inhibited, and foam stability decreased. RCA formed a stiffer, less mobile interface (dilatation and shear) and therefore inhibited the Gibbs-Marangoni flows altogether, which led to low foam stability which improved with increasing concentration (t1/2: 8-20 min). Clearly, the deletion of amino acids in caseins can greatly impact their interfacial and foaming behavior. These results highlight the potential for using different genetic variants of recombinant caseins for tuning its functionality.