Is cloudy cider vinegar safe to use for pickling?
Vinegar, especially cider or wine vinegar, may become cloudy and dark when stored. Cloudiness occurs when iron in the vinegar combines with tannins, which are responsible for the astringent flavor of many fruits including apples and grapes. The reaction is more likely to occur if the vinegar is stored in clear glass bottles exposed to light. Vinegar containing the same level of iron but stored in the dark may not become cloudy. Cloudiness is harmless. Since acidity is not affected, cloudy vinegar may be used for pickling.
