Is white vinegar safe to eat if you are allergic to wheat?
White vinegar is also called spirit vinegar. It's made by distilling ordinary malt vinegar to produce a very strong, colourless liquid high in acetic acid. It is less pungent than malt vinegar, and is often used in home-made pickles, especially where the colour of the food needs to be retained, for example pickled pears or silverskin onions.
Malt vinegar is made from barley, so white vinegar is by association also made from barley. However barley malt vinegar is made using a fermentation process, so the end product only contains a trace amount of barley protein and gluten.
(updated 07/10/13)
