Ovalbumin is a globular protein. When it is denatured, it can produce molecular species with different conformational states, each of which has different adsorption properties at a gas-liquid interface. Such changes in adsorption can then affect the foaming behaviors of ovalbumin. Results of semi-batch foam fractionation of both native and denatured ovalbumin aqueous solutions are reported in this paper, along with possible relationships between denaturation and foam fractionation outcomes, such as the enrichment ratio and mass recovery. Bubble size and foam stability are determined in the experiments to show the effect of denaturation on these measured parameters in this system. The relationships between the bubble size, void fraction, and ovalbumin enrichment are also reported to reflect the effect of the presence of denatured species.