Impact of protein self-assemblages on foam properties

The influence of dynamically heat-induced aggregates on whey protein foams was investigated as a function of the thermal treatment applied to WPI using a bubbling technique. The aim was to determine the interplay between the size/shape/proportion of the heat-induced aggregates and the properties of protein foams (formation and stability). Results showed that insoluble protein aggregates were highly branched and cohesive, whereas soluble aggregates were constituted by subunits, associated by hydrophobic bonds and formed by α-La and β-Lg monomers linked by disulfide bridges. Using the bubbling procedure, protein aggregates were shown to slow down significantly foam formation. However, the rate of foam formation remained nearly unchanged for wet foams when the amount of insoluble aggregates was inferior to 5% and when their size remained lower than 100 μm. Similarly, protein aggregates did not seem to affect the destabilisation kinetics of wet foams, regardless of amount, size, shape and proportion.