Interactions between volatile flavor compounds and food matrix components studied using nuclear magnetic resonance spectroscopic and solid phase microextraction techniques.

摘要

The interaction or binding of volatile flavors with nonvolatile food components influences the overall sensory perception of food flavors. In order to investigate the physicochemical interactions between volatile flavors and nonvolatile food matrix components, nuclear magnetic resonance spectroscopic techniques (NMR) were employed. Nucelar magnetic resonance (NMR) titration and two-dimensional NMR techniques applied to volatile/poly phenolic complexes provided evidence of the intermolecular interactions. The results revealed that gallic acid interacts more strongly with the aromatic flavors than naringin. The supramolecular complexation was dependent on the structure of the volatile flavors with 2-methylpyrazine and vanillin interacting more strongly than ethylbenzoate.; A diffusion-based nuclear Overhauser effect (called diffusion NOE pumping) method was applied to screen mixtures of flavor compounds and identify those that have a binding affinity to complex macromolecules. Using this technique benzaldehyde and vanillin were observed to bind with bovine serum albumin (BSA) while 2-phenylethanol was identified as a non-binding or weakly binding ligand with BSA. The diffusion NOE pumping method was also applied to a hydroalcoholic solution of a cacao bean tannin extracts where a mixture of ethylbenzoate, benzaldehyde and 2-phenylethanol was added to the extract. It was clearly indicated that ethylbenzoate had a stronger binding affinity to the cacao bean tannin extracts than the other two flavors.; The diffusion based-NOE pumping technique was then applied to determine the relative binding affinities between α- and β-ionones and β-lactoglobulin (BLG) at different pHs. The high affinity was observed for both aroma compounds at pH 9, which may be due to a flexible conformation of BLG under the condition so that the flavor ligand accessibility increases.; In the final study, changes in volatility of selected flavor compounds in the presence of nonvolatile food matrix components were studied using headspace solid phase microextraction (HS-SPME) combined with GC/MS quantification. Equilibrium dialysis followed by HS-SPME-GC/MS was carried out to confirm the ability of HS-SPME extraction for monitoring the free volatile compounds in the presence of proteins. Interactions between several selected flavor compounds and nonvolatile food matrix components (BLG or (+)-catechin) were also studied by means of HS-SPME-GC/MS analysis.