Genome Center metabolomics lab combines new, old technologies for red wine comparison

By now, there is a broad consensus that moderate consumption of red wine offers numerous health benefits, such as reducing the risk of heart disease. However, other studies indicate that red wine has no effect, is no more beneficial than grape juice, or that other types of alcohol are equally heart healthy. A possible source of this confusion may be the assumption that all red wines contain similar concentrations of flavor compounds such as resveratrol, a polyphenol known to reduce ‘bad’ cholesterol. Recently, UC Davis’ Oliver Fiehn, Director of the West Coast Metabolomic Center, and his graduate student Yan Ma employed a novel analytic technique to determine the abundance of resveratrol and other polyphenols in California wines made from the grape varietals Cabernet Sauvignon, Merlot, Petite Syrah, Pinot Noir, Syrah and Zinfandel. By injecting extracts of these wines into a variety of experimental chromatography columns 1 mm in diameter— a technique the authors call ‘micro liquid chromatography’— followed by tandem mass spectrometry, over 1,500 wine compounds were detected. Using the novel data processing software MS-DIAL, Yan Ma structurally identified over 250 wine components, including more than 160 polyphenols. In order to correlate the analytic results with more traditional organoleptic assessment, ‘a panel of fourteen non-trained adults tasted the remaining wines directly afterwards.’ Following optimization of the method, principle component analysis found that two varietals, Pinot Noir and Merlot, contained about 6 times as much resveratrol as the others. In Cabernet Sauvignon and Syrah, the flavor compounds triethyl citrate and syringic acid were found to be much more abundant. These compounds were found to correlate with drinker preference in the blind test. The new data could be helpful for grape breeders seeking to stabilize a particular flavor profile, or for consumers who seek to maximize the cardioprotective effect of what they drink. The report was published in the Journal of Agricultural and Food Chemistry: Ultrafast Polyphenol Metabolomics of Red Wines Using MicroLC-MS/MS