“Not guilty”, the plea of SO2

Ever felt like the world is against you, no one is on your side, you’re even doubting yourself? Try being the gaseous chemical compound Sulphur Dioxide. A useful if not vital part of wine preservation, centuries old and now outlawed by a younger wave of purists chasing the ‘vanilla’ wine… untouched, untreated and as a result, sometimes…. undrinkable.

Contrary to popular belief, there is no wine in the world without a trace of Sulphur. Volatile sulphur compounds (Hydrogen sulphide and mercaptans) are naturally produced through the activities of yeast during fermentation. The effects of yeasts on a wine are endless, our recent blog Wine Yeasts, small but perfectly formed sheds some light on the various strains and their duties in the must.

Legally, Sulphur Dioxide is regulated in viticulture and winemaking. Organic viticulture specifies a maximum of 100mg/l for reds and 150mg/l for whites, 50 mg under conventional rules. As with many of the rules with Organics, there’s still a lot of wriggle room. Many quality driven producers look for much lower levels of 30 – 80mg/l, something only possible through constant supervision at the winemaking stage and an educated approach to handling antiseptic and oxidasic issues along the way. Lowering the SO2 in winemaking is like letting down your force field and relying on soldiers in the field to protect your wine.

Imagine a world without SO2. Who would protect the delicate must of whites prior to fermentation, saving them from the perils of bacteria (by death), spoilage bacteria and undesirable more funky yeast strains (concussed supression). Pale lucid reds lacking the colour fixing properties of SO2 that encourages greater extraction of polyphenols from the skins.

Why ‘all or nothing’? Producers globally recognise that wine drinkers are looking for less additives in their wines. There are a number of ways to effectively protect the wine throughout fermentation and maturation thus reducing the need for large amounts of SO2. These include:

• Retaining a cooler temperature from grape reception through to bottling to reduce the risks of oxygen absorption.
• Methodical attention to detail when cleaning/sanitising barrels/winery equipment.
• Careful supervision of all stages of fermentation with regular analysis to ensure that volatile compounds or unwanted yeasts and bacteria aren’t dominating proceedings by bullying the good guys into submission.

Velcorin, ascorbic acid, metatartaric acid, sorbic acid, tartaric acid, gum arabic, lysozyme, carboxymethylcellulose…. reads like a list of bad guys in a Marvel movie. These are all possible additives used in the production of your wine. Why worry about the good guy when you have this lot sitting in the shadows enjoying their freedom outside the limelight.

The educated use of SO2 is a necessary tool in most wineries. A discussion for another day is the loss of a ‘sense of place’ when a wine is driven by yeast and bacteria generated properties or oxidative aromas. In London this week, the profile of respected Volnay producer Francois Buffet read: “He is another winemaker losing interest in zero-sulphur, feeling that the identity of the terroir can be lost without SO2’s guiding hand.” This is a subject to be continued…..