Distilled Vinegar Production
Distilled vinegar is diluted acetic acid, a major industrial chemical. Its major source used to be destructive distillation of wood, though today the major route is from a catalyzed reaction of methanol (wood alcohol) with carbon monoxide (yes, that poisoness gas from incomplete combustion). That said, most food-grade acetic acid and hence most distilled vinegar, is made from ethyl alcohol by fermentation with acetobacter bacteria, in a continuously stirred tank through which air or oxygen is bubbled. The "vinegar" produced over about two to three days is about 15% acetic acid. It is then diluted with water to make the store product. Industrial ethanol is made from ethylene gas from petroleum, but again the food grade product is made largely by fermentation of grains, predominently corn in the United States. The starch of corn has to be converted to sugars first, either by treatment with acid or enzymes (in brewing, the germinating grain produces the needed enzyme). Distilled vinegar, however, can be made from industrial ethanol.