Winemakers playing it too safe with SO2

Winemakers and bottlers are playing it too safe with sulphur dioxide in aromatic whites, according to the August edition of the drinks business.

High levels of free SO2 can bring sulphurous match-stick smells as well as muting fruit aromas

An article on SO² additions points out that high levels of the important preservative are muting the fruit character in aromatic whites – and the impact could be a bigger problem that TCA.

Recording a particularly excessive use of SO² for aromatic whites, Sam Harrop MW said liberal quantities were being added to the likes of Sauvignon Blanc because the wines rely on primary aromatics and often contain residual sugar.

Nevertheless, Harrop believes winemakers and bottlers are being too cautious and formulaic when it comes to the use of sulphur dioxide, which acts as an anti-oxidant in its “free” form.

“Part of the problem is that most winemakers around the world like to play it too safe when supplying wines for export, and they like to follow something of a formula,” he said.

With one big volume white wine, Harrop said that he achieved a huge improvement in quality simply by reducing the total SO² from 140 to 115ppm – some way below the European Union limit for white wine at 160ppm.

“In my opinion many winemakers don’t question the role of sulphur and its impact on aromatic intensity enough throughout the winemaking process”, Harrop stated, adding that he has worked in regions where it is normal for the mobile bottling line to set the levels of free sulphur in order to prevent any possible come-back.

Meanwhile, Geoff Taylor of UK wine analysis company Corkwise said that for quick turnover aromatic whites sold through the supermarket sector, there’s no need to add excessive SO² pre-bottling.

“Most major brands would be on the shelf and drunk within a matter of weeks”, he told db.

Speaking of the impact of SO² on whites, Taylor explained that it is unbound sulphur dioxide which has the greatest impact on a wine’s aroma.

“Free is the part you can smell,” he said, adding, “What a lot of people don’t realise is that prior to the stage of smelling sulphur dioxide, there is a muting of the fruit.”

Continuing he noted, “If you give people the same wine with different levels of SO² they are really surprised at the difference in quality.”

And in terms of the sheer number of bottles negatively affected by excessive sulphur additions, Taylor said that the issue is bigger than TCA.

The August edition of the drinks business contains a full analysis on the use of sulphur dioxide in winemaking, and considers the role of retailers and contract bottlers on the amount of the preservative used.

The article, which has been written by Tom Bruce-Gardyne, also looks at the history of sulphur dioxide use, labelling requirements and current legal limits.