The short answer to this question, which we receive from time to time, is: It doesn’t. The reason people continue to ask the question is that they are often puzzled by the fact that wine vinegar labels often do not have expiration dates on them.
In a sense, though, wine vinegar is already “expired.” That is, it is wine that has expired by becoming vinegar. But as vinegar, the powerful acidity in it will inhibit just about all bacterial growth.
You might be interested to know that the Vinegar Institute conducted studies on this issue and confirmed that vinegar’s shelf life is almost indefinite. Thanks to its acid nature, vinegar is self-preserving and does not need refrigeration. White distilled vinegar will remain virtually unchanged over an extended period of time.
The same thing applies to wine vinegar, which can be found in both white and red versions. The only thing you might notice with wine vinegar, especially the red variety, is a slight color change or the development of haziness or some sediment. But even these are only aesthetic changes that will not affect the taste, quality or safety of the vinegar. The product may still be used with complete confidence.
