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 beta-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-degrees-C. Affinities of binding for all flavor ligands were greater for glycinin than beta-conglycinin. Affinity for aldehydes increased with increasing chain length for glycinin, but remained constant for beta-conglycinin. DELTA-G-degrees, DELTA-H-degrees, and DELTA-S-degrees for binding were determined. DELTA-G-degrees 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 CH2 in homologous aldehydes was greater for glycinin than beta-conglycinin.