David on Technical Topics – Keeping Cognac

We are often asked how long you can keep a bottle of cognac once it has been opened and the answer is for quite a long time – provided the bottle is stored upright and the cork replaced firmly every time you take some out.  Cognacs deteriorate in the bottle over time for many reasons, the most common being that the bottle has been stored lying down.  Strong spirit affects the cork to a far greater extent than wine does stored in the same position; this action compromises the flavour and allows air into the bottle.  The more air there is in the bottle, the faster the cognac will deteriorate, however, cognac’s minimum strength is 40% abv so, providing that the cork or stopper is replaced firmly, there is no reason why it should not last up to ten years or even more.

Of course there is a limit as to how long you can store any spirit in a bottle, even unopened, and so much depends on the quality of the seal and the condition of the cork. Ultimately, even with the bottle in an upright position the seal around the cork will fail, air will enter the bottle and the alcohol will escape rendering the cognac with a completely unacceptable flavour.  This often happens with some very old cognacs from previous centuries and so the level of cognac in the bottle is important. We believe that cognac corks should be changed every twenty years but there are some in Cognac who recommend changing them every ten.  Perhaps the safest option is to drink and enjoy it!