Interaction properties of β-lactoglobulin and benzaldehyde and effect on foaming properties of β-lactoglobulin

Quenching of tryptophan fluorescence intensity and absence of covalently bound fluorescent products in β-lactoglobulin solutions containing benzaldehyde at various molar ratios, indicated that β-lactoglobulin monomer and benzaldehyde might associate through a non covalent binding mechanism. The affinity constant determined from perturbation of tryptophan spectrofluorescence spectra was close to that previously observed by other authors for retinol binding to β-lactoglobulin. In parallel foaming properties of solutions of β-lactoglobulin alone or in mixture with benzaldehyde were investigated through a conductimetric method. It was observed that addition of benzaldehyde to β-lactoglobulin led to enhanced foaming properties in comparison with β-lactoglobulin alone. These results were discussed in terms of formation of non covalently bound complexes with a specific surface activy.