75% of Bordeaux wines with no added sulphites showed faults

ccording to research by Edouard Pelonnier-Magimel, post-doctoral fellow at the Bordeaux Institute of Vine and Wine Sciences, 75% of Bordeaux red wines fermented without sulphites show faults.

“We bought 52 wines from the 2015 and 2016 vintages labelled as having no added sulphites in supermarkets, wine shops or directly from the estate”, he explains. “At the same time, we collected wines that were equivalent in terms of price, geographical region, and oak influence, but which contained SO2”.

The researchers first measured the total SO2 in all the wines. “Only 43 out of the 52 wines supposedly without added sulphites met the regulatory threshold of 10 mg/L. Four contained more than 30 mg/L and were removed from the study”, says Pelonnier-Magimel. The remaining wines were tasted blind by eight students studying for the National Oenologists’ Diploma (DNO) who are very familiar with Bordeaux wines.

“75% of the wines with no added SO2 were judged to be faulty by at least three of the tasters. The majority were oxidised, 25% showed notes linked to brettanomyces, and 14% had mousey flavours”. Conversely, only 25% of the 2015 wines with sulphites displayed faults. “The tasters found none in the 2016 vintage wines”.