Study of Interactions between Food Phenolics and Aromatic Flavors Using One- and Two-Dimensional 1H NMR Spectroscopy

Da-Mi Jung,† Jeffrey S. de Ropp,‡ and Susan E. Ebeler*†
Department of Viticulture and Enology and NMR Instrumentation Facility, University of California, Davis, Davis, California 95616
J. Agric. Food Chem., 2000, 48 (2), pp 407–412
DOI: 10.1021/jf9906883
Publication Date (Web): December 23, 1999
Copyright © 2000 American Chemical Society
†

 Department of Viticulture and Enology.

,
‡

 NMR Instrumentation Facility.

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*

 Address correspondence to this author at the Department of Viticulture and Enology, One Shields Ave., University of California, Davis, CA 95616-8749 [e-mail seebeler@ucdavis.edu; telephone (530) 752-0696; fax (530) 752-0382].

Abstract

Changes in flavor release and aroma characteristics in a medium including food phenolics may be attributed to an intermolecular interaction between flavor compounds and phenolics. To investigate the interaction, one- and two-dimensional NMR studies have been carried out on the binding of two phenolics, gallic acid and naringin, with three aroma compounds, 2-methylpyrazine, vanillin, and ethyl benzoate. Evaluation of thermodynamic parameters and intermolecular nuclear Overhauser effects reveals that gallic acid can interact more strongly with aromatic flavors than naringin. The supramolecular complexation is also dependent on the structural nature of the flavors, with 2-methylpyrazine and vanillin interacting more strongly than ethyl benzoate. The interaction is principally π−π stacking between the galloyl ring and the aromatic ring of the aroma compounds, but secondary hydrogen-bonding effects help to stabilize the complex and enhance the specificity.

Keywords: Food phenolics; nuclear Overhauser effect; supramolecular complexation; π−π stacking; hydrogen bonding; flavor interaction

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History

  • Published In Issue February 21, 2000
  • Received for review June 24, 1999. Revised manuscript received October 25, 1999. Accepted November 2, 1999. Financial support from the American Vineyard Foundation and the UCD NMR facility is gratefully acknowledged. The 500 MHz spectrometer used in this research was purchased in part with funds from NSF Grant OSTI-97-24421.

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