Investigation and Characterization of Flavor to Food Matrix Interactions using Solid State Nuclear Magnetic Resonance

Abstract

Intermolecular interactions between flavor molecules and food matrices are known to influence flavor release. However, the mechanistic interactions themselves remain largely uncharacterized and the dynamics unstudied. The overall goal of this research project is to develop a research platform which can characterize and observe the dynamics of flavor to matrix interactions. Solid state nuclear magnetic resonance (ssNMR) was applied to characterize molecular interaction dynamics at the atomic scale in flavored gum matrix model systems. Preferential interactions between flavor compounds (Melonal and ethyl propionate) and model polymers were detected and quantified. Chemical shift perturbances were calculated for Melonal in model matrices providing site-specific information. This methodology studied flavor to matrix interactions in situ, determined if preferential binding behavior exists and indentified which functional groups were involved in the interactions. Next, isotopically enriched model polymer matrices were utilized to assess differences in flavor to matrix interactions as physical properties of the matrix changed. Short molecular weight (MW), long MW and mixtures of the short and long MW matrices were mixed with carbon-13 labeled acetophenone. The interaction dynamics were studied using ssNMR. Acetophenone was shown to be more mobile, and therefore available to release, in mixtures of short and long MW matrices. Acetophenone release profiles also showed greater release from mixed short and long MW matrices. Quantification confirmed greater acetophenone release from blended short and long MW matrices. These effects were overlooked by a traditional thermodynamic based prediction method. Finally, the impact of polymer type and MW on the strength of interactions of a flavor compound was examined. Interactions between acetophenone and model matrices were further characterized by two-dimensional nuclear Overhauser effect spectroscopy (NOESY) combined with INEPT. These interactions were reported to occur between the aromatic carbons of acetophenone and the hydrocarbon backbone and side chains of D block. The strength of these interactions was affected by MW changes. In summary, the implementation and refinement of ssNMR techniques was able to provide deep insight into the flavor to matrix interactions which govern flavor release. This technology and approach has to ability to make significant gains toward understanding the mechanisms involved in flavor release.