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Winemakers deliberately mislead on alcohol content, study claims

Published:  04 January, 2016

Winemakers systematically misrepresent the alcohol content of their wines, according a new study from the University of California in Davis.

The study, published in the Journal of Wine Economics, reviewed the alcohol content of some 90,000 bottles of wine tested over a sixteen-year period.

For 57.1% of those wines, the average actual alcohol content was 0.42% higher than reported on the label.

Wines from the New World were less accurately labeled than those from the Old World, with an average discrepancy of 0.45% compared to 0.39%.

"Even errors of this magnitude could lead consumers to under-estimate the amount of alcohol they have consumed in ways that could have some consequences for their health and driving safety; and, in particular instances, the discrepancies could be much larger than average," noted Professor Julian Alston, the report's lead author.

Spanish reds are the least accurate among Old World wines, while in the New World, Argentine reds, American whites and both reds and whites from Chile are the worst offenders.

"It is as though the reported alcohol percentages are biased towards values of 13.0% by volume for Old World red, 12.5% for Old World white, 13.6% for New World red, and 13.1% for New World white," Alston said.

"The substantial, pervasive, systematic errors in the stated alcohol percentage of wine are consistent with a model in which winemakers perceive that consumers demand wine with a stated alcohol content that is different from the actual alcohol content.

"What remains to be resolved is why consumers choose to pay winemakers to lie to them."

Old World wines typically had up to 0.7% less alcohol than their New World counterparts, the study showed.

The study was a joint venture between the University of California Agricultural Issues Center, the Department of Agricultural and Resource Economics at the University of California, Davis, and the Giannini Foundation of Agricultural Economics.

It examined data provided by the Liquor Control Board of Ontario, which tests every wine imported into Ontario for actual alcohol content, among other characteristics.

The data studied ranged from 1992 to 2007 and originally comprised 127,406 wines, including 80,421 reds and 46,985 whites.

However, the team excluded both dessert wines and wines from Germany from its final findings, as well as incomplete data provided from 2008 and 2009.

Ultimately, 91,432 wines were included in the study.

Professor Alston is also director of the Robert Mondavi Institute Center for Wine Economics.