Interactions between aroma compounds and β-lactoglobulin in the heat-induced molten globule state

• Published in: Food chemistry 2010-04, Vol.119 (4), p.1550-1556
• Main Authors: Tavel, Laurette, Moreau, Céline, Bouhallab, Saïd, Li-Chan, Eunice C.Y., Guichard, Elisabeth
• Format: Article
• Language: English
• Subjects: acid treatment; Aroma compound; beta-ionone; beta-lactoglobulin; binding properties; Binding sites; circular dichroism spectroscopy; Food engineering; guaiacol; heat treatment; hydrophobicity; lactoglobulins; Life Sciences; ligands; Molten globule; molten globule state; nuclear magnetic resonance spectroscopy; odor compounds; protein binding; protein conformation; protein structure; Surface hydrophobicity; surface interactions; β-Lactoglobulin
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2009.09.041

The present study aims to elucidate the binding of small hydrophobic ligands onto the molten globule state of β-lactoglobulin (BLG). The conversion of the native BLG into a molten globule state was induced by heat treatment at acidic pH. The molten globule state was evidenced by far and near-UV circular dichroism spectra. β-Ionone and guaiacol exhibited a higher binding ability to BLG in the heat-induced molten globule state compared to unheated BLG, as assessed by protein surface hydrophobicity measurements, using 6-propionyl-2-(dimethylamino)naphthalene (PRODAN) fluorescent probe. The binding sites of the two aroma compounds were determined by 2D nuclear magnetic resonance (NMR) spectroscopy. The less tightly packed structure of the molten globule favoured ligand binding, in particular within the central cavity. The greater flexibility of the calyx entrance, and the conformational change of loop EF induced an easier access of the central cavity after the thermal treatment.