THE amount of alcohol in wine has risen around the world in the past 20 years, with a leading wine economist estimating there is 10% more alcohol in a standard bottle than what is written on the label.
Professor Julian Alston, the director of the Robert Mondavi Institute Center for Wine Economics at the University of California, gave an address about his research at a conference in port Macquarie on Wednesday.
He told the Australian Agricultural and Resource Economists Society that the alcohol content of both red and white wines had been rising steadily for two decades.
His research included data from Australia, Canada and the United States, and found alcohol content in most wines rose about 0.5% over that period.
While the research sought to look for rising alcohol due to climate change and hotter seasons, he said it was part of a directed strategy by wine producers.
"What we think is happening is that consumers are demanding wines with stronger flavours and higher sugar content of grapes," he said.
"So the higher alcohol is essentially a nuisance by-product of commercial decisions to produce fuller flavours in wine to suit consumers."
Prof Alston said while the increase was marginal, labelling laws had not kept up with higher alcohol content, saying many wines had about 10% more alcohol than that estimated on the label.
However, despite the discrepancy, he said it was still within the allowable limits for estimates of alcohol content under labelling laws.
"We find that for wines at the higher end of the range, the labels tended to understate alcohol content, and for wines at the lower end, they tend to do the opposite," Prof Alston said.
"I don't think it's a huge concern for consumers, but it is reasonable to ask the question of why we don't have a narrower definition of alcohol content for wine."
The AARES conference continues until Friday.