This is definitely the question I get asked the most. Sometimes, you and your partner just want a single glass of wine each, or maybe your partner doesn’t drink. However, once a wine comes into contact with the air, it starts to oxidise and deteriorate. It won’t be undrinkable, but it will lose some of that lovely fresh fruit.
White wines and sparkling wines tend to go downhill quicker than reds, and fortified wines last the longest. In general, white wines, if kept in the fridge with a cork, will last two to three days, and red wines three to five days. Red wines will keep their freshness longer if stored in the fridge. Fortified wines will usually last a few weeks.
You can use a special stopper to keep sparkling wine fresh, but I find these really only work for a maximum of 24 hours. To keep your still wines fresh, you could buy a half bottle of wine – preferably screw cap – and once consumed, fill it with half of your full bottle. This will certainly increase the wine’s shelf life, possibly for a week if kept chilled.
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There are gadgets such as the Vacu Vin that draw the air out of a bottle and seal it with a rubber bung. These work if the bottle is more than half-full, but I find they work less well after that. You could go for the very efficient Coravin, a machine that replaces wine with argon gas, allowing you to keep a wine in perfect condition for months. Restaurants use these to offer customers a single glass of special wine. However, they cost several hundred euro. I use one at home, but then, I taste a lot of wines.
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Buying quarter- or half-bottles is one option, but retailers tend to have a limited selection, and they can be very expensive compared to full bottles. Another option is the bag-in-box, which will keep wine fresh for weeks if not months. You can help yourself to as little or as much as you want, keeping the white wine in the fridge. The range is limited, but I suspect it will increase in the future – in Sweden more than 50 per cent of all wines sold are bag-in-box. O’Briens off-licences have a special promotion on at the moment with some attractive wines.
Of these options, I would argue that using an empty half-bottle is the best way to preserve your wine and allows you to choose from the full range of wines available in your local wine shop.