Tag Archives: sulphur

Screwcaps and ageing

Screwcap closures have had some bad press, but in my opinion, any wine destined to be drunk within a year of production should be sold in a screwcap bottle.

Ch.Margaux is carrying out trials with screwcaps

Ch.Margaux is carrying out trials with screwcaps

What is good about screwcap bottles

  • The closure does not contaminate the wine. The wine may still be corked because of contamination during wine production, but at least the screwcap won’t have caused it.
  • Every bottle will be the same as the next. There are some caveats, and you should refer to a previous blog for further details. Every natural cork is different, whereas every screwcap closure is identical.

What is bad about screwcap bottles

  • Removing a screwcap just doesn’t have the same theatre as removing a cork. Sadly, I can’t think of any solution to this problem.
  • Production of ‘reductive’ chemicals in the wine because air is excluded. These are sulphur compounds which may be produced in the bottle because of the absence of air. These compounds disappear quickly after a bottle is opened, but can be excluded by modifying the winemaking process.
  • A little bit of oxygen appears to be necessary for a wine to age gracefully. Original screwcaps allowed almost no air to reach the wine.
  • Screwcaps were associated with cheap wine, so producers of quality wine tended to shy away.

New developments

  • The seal in a screwcap is provided by padding at the top. Different materials are being used for this padding, which allow different amounts of oxygen to pass through. This means that they can potentially be used for ageing fine wine.
  • The obvious thing is to try long term tests, and some tests were initiated in the 1980s in Australia. However, the prestigious Château Margaux in Bordeaux has started their own long term trials. Endorsement by one of the great old names in the wine business would make all the difference in the acceptance of screwcaps. Time will tell.

Conclusion
By choosing the correct seal, there will be screwcap closure for every wine, but it may take a while to prove the point.

Sulphur Dioxide – the Magic Molecule

Sulphur Dioxide molecule

Sulphur Dioxide molecule

Sulphite additions to food and wine have become a big issue. However, the sulphites, and the sulphur dioxide that they produce have real benefits.

Why is the term sulphite used?
Sulphur dioxide is sometimes injected as a gas, but solid sulphite granules are usually added instead. The acid in wine rapidly splits this up to produce sulphur dioxide which actually does the work.

Sulphur dioxide occurs naturally in wine
This may seem unlikely, but fermentation of grapes produces sulphur dioxide without any help from humans. The amount depends on the the yeasts that are used, but it is a ‘natural’ product.

Why are sulphites added to wine?
There are two main benefits:-

  • Antioxidantif wine is exposed to air, the alcohol is quickly oxidised to acetic acid (vinegar). So, nature’s natural tendency needs to be moderated, if we are to drink the wine before it goes off. Sulphur dioxide attacks the chemicals which would otherwise produce vinegar. This is less of an issue for red wines which have their own antioxidants.
  • Antimicrobial – wine contains yeasts and bacteria. The magic molecule prevents these from multiplying and spoiling the wine.

Which wines have the most sulphur dioxide?
SO2 binds with many compounds in wine, including sugar. Only the unbound sulphur dioxide is able to fend off oxygen and microbes. So, sweet wines need plenty to protect them.

The importance of quality grapes
Rotten grapes make rotten wine, and need more sulphur dioxide to keep the bugs under control. Grapes with plenty of acidity also need fewer additions.

What are the adverse effects?

  • Sensoryan excess of sulphur dioxide produces a smell of burnt matches, but an awful lot needs to be added to have this effect. This fault is rare.
  • Healthis a difficult issue because there is little proof of adverse effects. It may induce asthmatic attacks in some people. It is worth noting that normal food metabolism in the body generates much more sulphites than you would absorb from wine consumption.

Conclusion
In my opinion, the addition of sulphites at the right time and in the right quantity is beneficial, if not essential, for almost all wine.