Following government’s approval of the use of ultraviolet light energy for liquid purification in oenological practices, acceptance of turbid liquid photopurification company SurePure’s technology has gained momentum among local winemakers.

SurePure marketing executive Steve Miller says the approved SurePure photo- purification method uses light energy to disinfect wine.

The technology limits harmful chemical intervention, reducing the need to add sulphur and other disinfectant additives.

Miller explains that the technology can replace, or act as an adjunct to, many other traditional wine filtration processes.

“It can replace sterile filtration, which strips colour and flavour from wine. Photo- purification also requires less chemical intervention, either with sulphur or other substances such as dimethyldicarbonate or pimaricin, which has now been banned in the South African wine industry,” he says.

In addition, the technology has a positive impact on the environment and on consumers’ wellbeing, reports the company.

Miller notes that the focus on reducing sulphur content also ensures a more sustainable and less environment-invasive approach to winemaking.

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SurePure technology was used by Spier Wines in the 2009 and 2010 vintages.

Spier Wines winemaker Johan Jordaan says he initially used the technology to treat wines that suffered from stuck fermentations prior to restarting them.

“This wine was passed through the SurePure unit once, without being filtered. The volatile acidity of this wine was stable and after the successful referment, the wine had no sluggish or stuck ferment odours. I have also used it to stop the fermentation of a rosé to have a higher residual sugar content,” he says.

Jordaan believes that there is a place for the SurePure technology in the market and that good wines with low sulphur can be produced, provided that the fundamental rules of chemistry are followed to preserve them.

“I think that white wines with a low sulphur content should be drunk very young or sealed with a screw cap to preserve the freshness, whereas the red wines can be stored for longer, provided that you have ample extract in the form of tannin to help preserve the wine against oxidation,” says Jordaan.

To prove his theory, Jordaan bottled a Merlot wine from the 2009 vintage, and closed it with a screw cap as a sample.

He did not add sulphur, acid, tannin or any other substances to the wine before or after fermentation.

“The sample stood in my office for two years. I opened the wine prior to the 2011 harvest to taste it. The wine was fresh and clean – no oxidation, no off flavours and no browning of colour.

“I expected oxidation, at least. This proves the point of low, or even no, sulphur. The fact that the wine passed through the SurePure unit only once makes it even more interesting. I did not do chemical- or micro-analyses on the wine, but organoleptically, it was fine, even after two years on a desk in an office,” he says.

Further, Steenberg Vineyards also used the technology to limit the amount of sulphur needed to treat its wines.

“We treated a batch of Merlot in 2009. No sulphur was added to the grapes or to the wine, and the wine showed more colour and more pronounced fruit in its youth. The wine showed that different flavour compounds, with fresh fruit flavours, could be a good blending component. After 12 months’ ageing in barrels, the wine showed slightly more oxidation characters than the ones with sulphur added, but still with good freshness,” Steenberg Vineyards winemaker JD Pretorius explains.

Meanwhile, Villiera Wines cellarmaster Jeff Grier used the SurePure process on a sulphur-free base wine.

Grier adds that Villiera Wines is exploring some other opportunities this year and intends to use SurePure for additional microbiological security.

SurePure expects an increasing number of vineyards to adopt the technology in the near future. “A growing consumer preference for fresher wines, combined with wine- makers’ focus on a less invasive approach to winemaking, and increasingly draconian additive legislation, makes SurePure a sure bet for the future,” says Miller.

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