The first thing to note is that flavorings, concentrated aromas, do not “spoil” or “go bad”. For instance, if you have a Milk flavoring sitting on your shelf for over 3 years, it won't taste like spoiled milk. ... These are synthesized concentrated chemical aromas. So there's no need to worry about spoiling.

Does imitation flavoring go bad?

When it comes to the imitation, after a few years of storage its quality will degrade. That means that at a certain point the flavor won't quite be there. When that happens, it's time to throw the extract away and buy or open a new bottle.

How long do imitation flavorings last?

We looked at the storage recommendations from several flavoring manufacturers and they say that extracts tend to have a shelf life of 6 months to 1 year. The exception to this is pure vanilla extract which, if stored in a cool dark place and tightly sealed, can last indefinitely and even improve with age.