Progress 10/01/02 to 09/30/07
Outputs
In this project, we have explored several new methods for the analysis of polyphenolic substances, in particular electrochemical methods, but some other methods have also been developed. First, we demonstrated that cyclic voltammetry can be used to detect the presence of phenolic substances that are found in wine. This method distinguishes many classes of compounds, but not individual substances. Second, we utilized radio-labeling to tag anthocyanins for analysis. This allowed the detection of anthocyanin molecules into wine tannin, along with a comparison of the number of anthocyanin functional groups versus the molar absorptivity of the wine pigments. Third, we developed the use of fast HPLC columns for analysis of wine polyphenols. This reduced our analysis time by half. Fourth, we created an analysis procedure to quantify the amount of grape seed tannin that was added to turkey meat. It would be added to that meat as a preservative. Fifth, we reported on a
comparison of many different analytical methods for phenolic substances, comparing and correlating the results. Each study resulted in a publication.
Impacts
Because of the complexity of phenolic substances in wines and other foods, their analysis is a challenge. Each of the new methods and the improvements to existing methods will help further the study and utilization of these valuable and important compounds in food processing, preservation and aging. For instance, the fast analysis method will allow for expanded experiments in winemaking, because the scope of an experiment is often limited by the number of samples that can be analyzed by the slow and tedious HPLC analysis of the sample. Also, there is much concern and confusion about the nature of some phenolic analytical procedures. The comparison study helps explain the relationship between the various methods.
Publications
- Ibern-Gomez, M., C. Andres-Lacueva, R.M. Lamuela-Raventos and A.L. Waterhouse. 2002. Rapid HPLC Method for Phenolic Compounds in Red Wines. American Journal of Enology and Viticulture. 53: 218-221.
- Kilmartin, P.A., H.L. Zou, A.L. Waterhouse. 2002. Correlation of wine phenolic composition versus cyclic voltammetry response. American Journal of Enology and Viticulture. 53: 294-302
- Lau, D.W, A.J. King, A.L. Waterhouse. 2003. An assay to estimate tannins added to postmortem turkey meat. Journal Agriculture Food Chemistry. 51: 6640-6644.
- DeBeer, D., J.F. Harbertson, P.A. Kilmartin, V. Roginsky, T. Barsukova, D.O. Adams, and A.L. Waterhouse. 2004. Phenolics: a Comparison of Diverse Analytical Methods. American Journal of Enology and Viticulture, 55: 389-400.
- Zimman, A., A.L. Waterhouse. 2004. Incorporation of Malvidin-3-Glucoside into High Molecular Weight Polyphenols during Fermentation and Wine Aging. American Journal of Enology and Viticulture. 55: 139-146.
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Progress 01/01/06 to 12/31/06
Outputs
We have developed a new method to measure the products of wine oxidation. Wine polyphenols react with oxygen to yield hydrogen peroxide. It in turn reacts with many wine substances, primarily alcohols, to yield aldehydes and ketones. An old traditional method for measuring such carbonyls was to react them with a hydrazine to make hydrazones that were crystallized to identify the carbonyl. We have adapted this reaction and instead of obtaining a melting point of a crystal, we separate the products by HPLC and characterize them by Mass Spectral detection. This allows us to quantify many oxidation products simultaneously.
Impacts
Wine oxidation is very important in both improving and damaging quality. This method allows the detection of many wine oxidation products. This is an essential tool in studying wine oxidation chemistry. This work has been prepared for submission to a journal.
Publications
- Pinelo, Manuel, Felipe Laurie, and Andrew L. Waterhouse. 2006. A simple method to separate red wine: Non-polymeric phenols and tannins by solid-phase extraction. Journal of Agricultural and Food Chemistry, 54, 2839-2844.
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Progress 01/01/05 to 12/31/05
Outputs
We have investigated a quick and simple method to separate monomeric polyphenols from the oligo- and poly-meric substances from wine. This is accomplished by using a C-18 solid phase extraction cartridge, and eluting the adsorbed substances with solvents of increasing power. This can be applied to many samples very quickly for a rapid separation of these fractions. The effectiveness of the method was verified by chromatographic analysis of both the monomeric and polymeric fractions that were eluted. It may also be applicable to other samples containing phenolic substances.We have investigated a quick and simple method to separate monomeric polyphenols from the oligo- and poly-meric substances from wine. This is accomplished by using a C-18 solid phase extraction cartridge, and eluting the adsorbed substances with solvents of increasing power. This can be applied to many samples very quickly for a rapid separation of these fractions. The effectiveness of the method was
verified by chromatographic analysis of both the monomeric and polymeric fractions that were eluted. It may also be applicable to other samples containing phenolic substances.
Impacts
This will allow investigators to quickly separate phenolic fractions that have very different chemical and biological properties. This will have broad application in health-related studies where current practice includes no separation of these fractions, despite the fact that the polymeric fraction has little biological activity or confounding activity.
Publications
- Pinelo, Manuel, F. Laurie, and A. L. Waterhouse. 2006. A simple method to separate red wine: Non-polymeric phenols and tannins by solid-phase extraction. Journal of Agricultural and Food Chemistry, submitted.
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Progress 01/01/04 to 12/31/04
Outputs
We have made progress this year in studying how cyclic voltammetry can be used to study the polyphenol composition of wine. This methodology can be used in polyphenol analysis because being antioxidants, these substances are easilty oxidized. The method of cyclic voltammetry is based on the oxidation of the substances in a sample and displays the voltages at which substances in the sample oxidize, so there can be some discrimination between substances based on different oxidation potentials. When analyzed using cyclic voltammetry, the polyphenols give characteristic responses. In particular, the flavonols, such as quercetin, oxidizes first, at approximately 400 mV (relative to Ag/AgCl), and then at 500 mV, the anthocyanins oxidize, and then at 600 mV the flavanols and condensed tannins oxidize. Unfortunately, when the tannins oxidize, the electrode becomes fouled and it only works very poorly. Good data can be obtained by stopping the voltage at 500 mV, but this
reading does not include the tannins, so the majority of the polyphenols are not measured. There is a good relationship between data obtained by this method and other for the flavonols, but the voltage limitation precludes the method from tannin measurement or total phenol measurement. Future studies will focus on overcoming the fouling problem in order to expand the utility of the method.
Impacts
The flavor of red wine is strongly affected by its tannins and phenols. Its antioxidant properties are important for storage. We hope that this electrochemical method will be able to discern what the wines antioxidant capacity will be, thus determining a aging potential for the wine.
Publications
- Waterhouse, A.L., and A. Zimman, The Fate of Malvidin-3-glucoside in New Wine, in Red Wine Color, Revealing the Mysteries. A.L. Waterhouse and J.A. Kennedy (Eds.) ACS Symposium Series, 886. American Chemical Society, Washington D.C., pp 217-231 (2004).
- DeBeer, D., J.F. Harbertson, P.A. Kilmartin, V. Roginsky, T. Barsukova, D.O. Adams, and A.L. Waterhouse, Phenolics: a Comparison of Diverse Analytical Methods. American Journal of Enology and Viticulture, (2004) in press.
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Progress 01/01/03 to 12/31/03
Outputs
To date we have not made major progress on this project, largely due to a lack of funding in this area as well as a lack of personnel skilled in the areas needed for advancement. However, we have made a small amount of progress by our study of tannin-anthocyanin reactions during wine aging. These studies have shown that most if not all anthocyanins do in fact bond covalently with tannins, giving rise to chemical changes that likely will change the sensory properties of those tannins. By using radiolabeled derivatives of the grape pigments, anthocyanins, we conducted tracer studies to show specifically and quantitatively how much anthocyanins react covalently with tannins to yield "pigmented tannin". While our methodology cannot determine the exact chemical form of the product, we were able to show that the light absorbance properties of the pigmented tannin does change over time, showing that multiple forms actually exist. Another important finding was that the rate
of the chemical reaction was not affected by the pH or acid level in the wine being aged. Since most of the postulated chemical reactions relied on acid to catalyze the reaction, these results show that those hypothesis cannot lead to most of the pigments formed in the wine. Thus new reactions must be described to explain our results.
Impacts
The flavor of red wine is strongly affected by its tannins and the specific taste characteristics of those tannins are thought to change during aging by reaction with the grape pigments called anthocyanins. Our recent research shows exactly how much anthocyanin reacts with wine tannins. These studies will help explain those important changes in red wine taste.
Publications
- Zimman A. and Waterhouse, A.L. 2004. Incorporation of Malvidin-3-glucoside into High Molecular Weight Polyphenols During Fermentation and Wine Aging, American Journal of Enology and Viticulture, In Press.
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