About Sandra Lim
When you open a bottle of wine, particularly red wine, you need to let it breathe, particularly for very young wines, so that oxygen releases some of the lovely aromas and the deepest darkest flavours packed into the wine.
However, if you've cut open an apple and leave it even for 15 minutes, it will start going brown. This is oxidisation. Apples and wine contain anthocyanins and phenols which contribute to the aromas in wine. Red wines also have tannins.
All of these react with oxygen and by letting the wine 'breathe', you're allowing these chemicals to react with oxygen and create the aromas we all love in wine.
As the aromas in conjunction with our taste buds contribute to our sense of taste (because as you know if you have a blocked nose, your sense of taste is massively reduced, which leads to everyone saying it tastes like cardboard or chicken), the wines flavour changes as well with the addition of these newly-release aromas in the wine.
This is what is meant by oxidisation: in the short term it's a good thing as we explained. Unfortunately, this is a party that requires fuel - the oxygen and these chemicals, and once they've all depleted, the wine then loses balance and the rest of the liquid starts to lose balance as these chemicals are removed and changed in the liquid.
In addition, leaving wine open for a long time, because there's wild yeast in the air, while you won't notice it in the period of a dinner party, over several days the wine begins to ferment further, and thus it slowly turns into vinegar.
Three quarters of a bottle of vermouth is wine, so what happens to wine can happen to vermouth. However vermouth is fortified, meaning it's had up to a quarter of the liquid added with neutral spirit as well as sugar and other spices that makes vermouth so tasty. This fortification goes a long way to stopping wine from fermenting and also helps preserve the vermouth for considerably longer than wine once open.
But unfortunately, even with this added defence, nature will take its course, and vermouth will last somewhere between 4 and 8 weeks once open. You can get extremes that a particularly well looked-after vermouth that's been kept well can last nearly 6 months, and you also get some vermouths that will go off as quickly as wine. But as a general rule of thumb we recommend that vermouth be drunk within 6 weeks of opening.
Therefore to store vermouth and wine properly, you need to somehow reduce both the oxygen and the yeast that's in air naturally from oxidising and further fermenting the wine respectively.
The best way to get rid of oxygen is to simply pump the air out of a bottle using a vacuum stopper, such as Vacu Vin. By pumping the air out of the bottle, you reduce the oxygen and thus the fuel for which the reaction takes place, therefore slowing it down considerably and making the liquid last longer.
To stop the fermentation, pumping the air out also removes most of the wild yeast in air that restarts the fermentation, but more importantly, by putting it in the fridge, you're lowering the temperature which means yeast becomes dormant and doesn't do it's job of fermenting and any bacterial growth that may also contaminate the wine.
Even by storing it in the fridge and with a vacuum stopper, we still recommend drinking it within 6 weeks, but with these two methods at least you can more-or-less be pretty certain it will last that long.