Temperature Effect on Binding of Volatile Flavor Compounds to Soy Protein in Aqueous Model Systems

The thermodynamics of binding was determined for soybean glycinin and β‐conglycinin and flavor ligands butanal, pentanal, hexanal, octanal, 2‐ and 3‐hexanone, 2‐ and 5‐nonanone, hexanol, and hexane. Hexane had affinity for these proteins only at 5 o C. Affinities of binding for all flavor ligands were greater for glycinin than β‐conglycinin. Affinity for aldehydes increased with increasing chain length for glycinin, but remained constant for β‐conglycinin. ΔG o , ΔH o , and ΔS o for binding were determined. ΔG o was negative for all ligands and ranged from −1.74 to −4.16 Kcal/mol. All enthalpies of binding were positive except butanal and hexanol. Change in free energy of binding per CH 2 in homologous aldehydes was greater for glycinin than β‐conglycinin.