Effect of Polyphenol Compounds on the Headspace Volatility of Flavors

¹ Department of Viticulture and Enology, One Shields Avenue, University of California, Davis, CA 95616-8749.

email: seebeler{at}ucdavis.edu

The overall objective of this study was to investigate the effect of nonvolatile polyphenols on the volatility of flavor compounds in solution. The first set of experiments evaluated the effect of two polyphenols, naringin and gallic acid, on the volatility of two flavor compounds, ethyl benzoate and 2-methylpyrazine. In the second set of experiments, extracted grape tannins were added to Chardonnay and Cabernet Sauvignon samples. The headspace volatility of the flavor compounds was analyzed using headspace solid-phase microextraction/gas chromatography (HS-SPME/GC) and results were compared to sensory studies. Results showed that the structures of both the flavor compound and the polyphenol influenced the magnitude of the interactions. Gallic acid significantly decreased the volatility of 2-methylpyrazine, while naringin had less of an effect on the headspace volatility of this flavor. Ethyl benzoate had the least interaction with both polyphenols. The sensory data gave similar results, with 2-methylpyrazine intensity the most affected by polyphenols. When tannins were added to wines, a significant effect on flavor volatility was observed by GC analysis, but effects were less apparent by sensory evaluation.

Note:
Acknowledgments: Financial support was provided from the American Vineyard Foundation, the California Competitive Grant Program in Viticulture and Enology, and USDA, CSREES, NRICGP Grant # 2001-35503-10028. The authors thank Doug Adams and James Harbertson for the tannin and Kevin Scott, John Thorngate, and Da-Mi Jung for technical help. The participation of the sensory judges is gratefully acknowledged.

Key words: HS-SPME/GC-MS, "true" headspace, polyphenol/flavor interactions, volatility, sensory evaluation, tannin