14B-9

W. CHOBPATTANA, I. J. Jeon, and J. S. Smith. Dept. of Animal Sciences and Industry, Kansas State University, Call Hall, Manhattan, KS 66506

The intensity of vanillin flavor in a food system is affected greatly because of its interaction with food components, especially proteins. The interaction of vanillin and proteins may occur through the formation of covalent bonding via the Schiff base arrangement. However, hydrogen bonding and/or hydrophobic interaction also may play an important role.

Our objectives were to investigate importance of hydrogen bonding and hydrophobic interaction on the reduction of vanillin in milk protein systems and to understand the effect of different proteins on vanillin reduction.

The model system consisted of vanillin and sodium caseinate or bovine serum albumin (BSA) in phosphate buffer at pH 6.5. Urea was used as a hydrogen bond-disrupting agent, whereas sodium dodecyl sulfate (SDS) was used as a hydrophobic bond-disrupting agent. Free vanillin was isolated from the protein matrix by centrifugal ultrafiltration and analyzed for its change in concentration by HPLC using a C18 reversed-phase column with a UV diode-array detection system.

Our results showed that the reduction of vanillin occurred instantly as it was added to the protein system. Vanillin decreased steadily as the concentration of proteins increased from 0 to 6%. The BSA interacted more with vanillin than sodium caseinate. Hydrogen bonding appeared to be the major force on the interaction of vanillin and sodium caseinate, whereas hydrophobic interaction was negligible. On the other hand, the interaction of vanillin and BSA seemed to be involved more with hydrophobic interaction than hydrogen bonding.

These results suggest that chemical reactions and binding forces involved in the reduction of vanillin were significantly different with the two proteins. This finding may have significance for better understanding of the chemistry, as well as minimizing the potential loss of vanillin in food systems, especially nonfat food systems, by disrupting formation of the weak binding forces or altering type of proteins.