Enhancement of Stability of Bubbles to Disproportionation Using Hydrophilic Silica Particles Mixed with Surfactants or Proteins - Food Colloids: Self-Assembly and Material Science - page 368

The use of hydrophilic particles mixed with b-LG gave considerable en-
hancement in stability compared to the protein on its own. This was not the
case with b-casein, however, where hardly any stable bubbles could be formed
at all. The increase in bubble stability with b-LG was not as great as with
DDAB + silica - but it is not clear how the presence of b-LG might affect the
particle hydrophobicity, if at all. As there was no enhancement in stability with
b-casein, it is tentatively proposed that the particles may become embedded in
the adsorbed b-LG layers around the bubbles, rather than directly adsorbing to
the surface of the bubbles. Confocal microscopy has provided some additional
support for this hypothesis. 10 So, in the case of b-LG, it is suggested that a
protein-particle composite is formed as bubbles shrink, and that this composite
ultimately has enough mechanical strength to inhibit disproportionation more
effectively than the protein film on its own. Such a mechanism is not possible
with b-casein because this disordered protein does not form a strong coherent
adsorbed film.
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