White wine vinegar is white wine that has been fermented and oxidized into an acid with a lightly fruity flavor. The distilling process usually takes place in stainless steel vats called acetators that expose the ethanol in the wine to oxygen. The resulting acetic acid is then diluted with water to a palatable acidity, somewhere between 5 and 7 percent. While the provenance of grapes used in something like Italian balsamic vinegar is known (in such case, Trebbiano or Lambrusco), white wine vinegars can be crafted from a blend of wines referred to as “wine stock.”