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Oxygen: the good and the bad

Decanting wine

Question from Marcus: I’d like you to explain oxidisation and the effects of oxygen on wine. I guess it all ties in with decanting/aerating your wine before serving.

In a nut shell: You decant wine to develop aromas and flavours but be warned that decanting aged wine for too long can actually ruin it. A little more on oxidisation below.

In a clam shell: Oxygen is both good and bad for wine. We decant wine for two reasons (and when I say decant wine you don’t need some fancy pants expensive decanter, a water jug will do). The first reason we decant wine is to separate it from the sediment (shit bits you get at the end of a bottle of wine that has been aged for a while) which can make the wine astringent. We also decant wine to aerate it. As wine is poured it’s exposed to oxygen. The wine sucks in all that delicious oxygen which opens up the aromas and flavours of the wine and enables the wine to develop. This is particularly useful for young wine or wine with high tannins (that chalky, mouth drying feeling that Cabernet Sauvignon gives you after a big gulp).

It’s good to decant young wine because the aromas and flavours haven’t had much time to develop so they might be harsh and lack flavour. By decanting a young wine for at least 20 minutes you’ll allow the astringent flavours to soften and open up creating more complexity. If you can control yourself it’s really interesting to decant a bottle of young wine and take a sip every hour for a few hours. You’ll notice a change in subtlety.

So I guess that’s the good and now for the bad – old wine and decanting. An old wine has had plenty of time to age in the barrel and bottle so it doesn’t need the boost that a young wine needs. If you are decanting an old wine you should drink it immediately. An old wine is very delicate and needs minimal oxygen exposure. If you leave it for too long you’ll run the risk of overexposing it and ruining the wine. Don’t do it!

It’s probably worth mentioning here that very few wines improve in the bottle (well very few cheap wines anyway). If it started out as an ordinary wine you’re not going to improve it by ageing it, in fact you’ll probably make it taste worse because you’ll lose those fruit flavours. Don’t save it in the hopes that it’ll taste better further down the track, it won’t. Make a delicious pie out of it now to save yourself the disappointment. But if it started out as a good wine, 10 years down the track the fruit flavours will remain and other complex flavours will develop.

There is a preconception that aged wine is better but it’s all down to personal taste. While I can appreciate an aged wine, in most cases I prefer the newer model. So don’t go paying a fortune for an aged bottle unless you know you like aged wine or you’ll be very disappointed!

So once you’ve cracked a bottle how long should you keep it for before pouring it down the sink? We now know that wine oxidises when exposed to air, eventually creating sherry-like off odours and a brownish tinge. The more surface area exposed the quicker it will spoil. And white wine will go bad quicker that red because it doesn’t have any tannins to preserve it.

Pour your leftover wine into a plastic bottle and squeeze as much air out as you can, screw the top on and keep it in the fridge (that goes for reds and whites but just make sure you take the red out of the fridge a few hours before drinking it again). Things last longer in the fridge! Keep your white wine for three days (max) if it’s been stored in the fridge. And if it’s a tannic red (think Cab Sauv or Shiraz) keep it for 5ish days (max) before it starts to go bad.

To read more about keeping opened wine and preserving it click here!


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