Do you wonder if the bottle of vinegar on your kitchen shelf will go bad anytime soon? When is vinegar no longer useable? Or does red wine vinegar go bad? The answer to all of these questions is never. Vinegar does not go bad unless it is contaminated by an outside source. For instance you were storing vinegar in a bottle and the lid was not on properly and dust or some foreign particles got into the liquid. Then the vinegar would not longer be good to eat and you most assuredly would be able to tell bad vinegar from a good just by looking at it. That is very rare though.
Can red wine vinegar go bad? Mostly, vinegar will never spoil, turn, or go bad. Vinegar does not have an expiration date and can probably stay on a shelf indefinitely. The reason being that vinegar is created through a fermentation process. Vinegar is the final stage of a sugar molecule’s life. In this stage, sugar begins to ferment and then becomes alcohol. The alcohol ages over time and turns into acetic acid and it is this acid that makes vinegar. There is no expiration date once vinegar is made; even each step in the vinegar making process has no end really. Vinegar can ferment for years and better yet, the longer vinegar is left to sit the better the taste it develops.
Red wine vinegar expiration is unlikely since vinegar is a fermented product it has the ability to be still good to eat years from now. So, do not shy away from vinegar that has been sitting in your cupboard or pantry for some time. Wondering what the shelf life of red wine vinegar is? Basically all types of vinegar have an almost indefinite shelf life. The acid nature of vinegar is what makes the product self preserve its tangy goodness. Vinegar does not need to be refrigerated because it is self-preserving and is happy to sit in room temperate on a shelf.
Distilled white vinegar stays the same no matter what even over long periods of time but other vinegars may exhibit some change in their appearance. Over time some other types of vinegars will change in color or become hazy due to sediment developing but these changes are only to the appearance of the liquid. The vinegar is still fine to eat and can be used with the confidence of knowing the product is still good.
Besides the vinegar becoming cloudy or developing sediment over time, a slimy substance might appear on the surface of the liquid. This icky looking stuff is called the vinegar mother and is nothing to worry about. The vinegar mother simply signifies that the vinegar is still alive and well. You can even remove the mother to make a new batch of vinegar.