Wines’ regional ‘fingerprints’ traced12th August, 2014 by Simon Howland
Wines have unique individual chemical characteristics which could be used to identify the region, assess quality and even help prevent fraud.
Researchers at the University of California, Davis, have undertaken an extensive comparative regional study of the Malbec grapes from various sites across Mendoza, Argentina and California, US.
As reported by the BBC, the researchers are attempting to fingerprint “terroir”, the unique characteristics of a wine linked to geography, geology and climate which, some argue, explains the differences between fine wines from around the world.
Typically subjective assessments of wines, and wines from specific regions, as based on appearance, aroma, taste and texture, all of which combine to create a wines flavor.
But, according to the BBC, demand is growing for something more objective to help consumers bypass inconsistencies in descriptions and help auction houses detect fraud, a growing problem highlighted recently in the case of Rudy Kurniwan in the US.
As reported in the drinks business, Kurniwan was recently sentenced to ten years in prison after defrauding victims of a combined sum of over $30 million in a fake wine scam whereby he sold off lesser quality wines under the labels of some of the worlds most sought.
As part of an ongoing search for a foolproof test to identify the provenence of fine wines, which has already seen the application of carbon dating and particle accelerators, the UC Davis team shifted the focus to volatile compounds, the compounds responsible for the different smells associated with different wine styles.
The researchers took Malbecs from 41 different sites across the two regions and asked a panel of expert tasters to assess them for 20 different sensory characteristics including aroma and taste.
The wines were all from the 2011 vintage, all fermented in stainless steel and, wherever possible, treated exactly the same across the test group and underwent standardized maceration times and identical storage conditions.
Common descriptors of the Malbec wines were aromas of cooked vegetal, earthy, soy and volatile acidity, as well as acidic taste and astringent mouthfeel, regardless of the region of origin.
The Argentinean Malbecs tended to have more ripe fruit characteristics, sweetness and higher alcohol levels, while those from California were more bitter, and had more artificial fruit and citrus aromas.
These differences were not only subjective – they were mirrored in distinct chemical profiles detected by gas chromatography-mass spectrometry, according to the results presented at the Amercian Chemical Society meeting.
The wines were clearly separated, based on their chemical and sensory profiles, by wine region and country.
But no matter how exclusive the terroir or vintage, the delicate balance of flavours in a bottle can quickly be ruined if poorly stored in a home cupboard or cellar, according to Italian scientists as reported in the drinks business.