Monthly Archives: October 2013

Bottle variation

Bottles of the same wine may taste very different, and variations increase as a wine gets older. In fact one bottle of a mature wine may be wonderful, and the next over-the-hill. Why?

different bottle sizes

different bottle sizes

The blend
Virtually all wine is a blend from different barrels or vats. If the mixing vat is not big enough to take all the wine, then one batch may well differ from the next. So, there may be a difference before the wine is even bottled.

Bottling
A particular wine may be bottled in batches rather than all at the same time. The fill levels, added sulphur dioxide, entrained oxygen, and gas injected above the wine may all vary at each bottling session.

The closure
Historically this was always natural cork. It is a fine closure, but every cork is different and will allow differing amounts of air to diffuse through. This causes bottles to mature at different rates. One big advantage of screwcaps is that each closure is the same.

Transport and storage
This is a major issue, and can completely destroy a wine.

  • Temperature – is covered in more detail by another post. If the temperature gets too high, the wine will be damaged, perhaps fatally. Cases of wine stored at different temperatures will mature at different rates.
  • ‘Lightstrike’ – damage by over-exposure to UV light.

Bottle size
The larger the bottle, the more slowly and gracefully a wine matures. This may just be because the gap between the cork and the wine is the same for a half bottle, a bottle or a magnum. Any air in that gap will be spread more thinly in a magnum than a half bottle, meaning that it will be oxidised more slowly.

Age of the wine
The older a wine, the more time there is for all these influences to take effect, and the higher the chance of one bottle being very different to the next.

Climate change and wine

There are plenty of climate change sceptics, but it is a fact that alcohol levels in wine are increasing, and some grape varieties ripen, where they wouldn’t have 20 years ago.

Why is alcohol level an indication of higher temperatures?
Higher temperatures produce riper grapes, which have more sugar. During fermentation, the sugar turns to alcohol, so more sugar leads to more alcohol. There is an associated decrease in acidity.

Some grapes need more heat to ripen

Some grapes need more heat to ripen

Different grape varieties prefer different temperatures
The diagram shows that some grape varieties need longer heat exposure to ripen than others.

  • If the temperature is higher than ideal, the grapes will ripen, but the wine will lack freshness and acidity.
  • If the temperature is lower than ideal, then the grapes won’t ripen properly, and the wine will be tart and acidic.
  • If the temperature is much higher than ideal, then the vine simply shuts down, and nothing happens.

Which countries are most affected?
Those at the current extremes of temperature for growing vines:-

  • Much of Australia and Spain, for example, have vineyards in regions with high temperatures. They will have to adapt to survive.
  • Countries further from the Equator with more marginal climates, such as England, will now be able to grow a much wider range of grape varieties.

What can the adversely affected regions do about it?

  • Plant different grape varieties, which are more tolerant of the hot weather.
  • Train the vine branches so that leaves physically shade the grapes.
  • Allow plants to grow between the vines, as this lowers the soil temperature, and there is less reflected heat from any stones.
  • Plant new vineyards at higher altitude.