Malt Vinegar is made from malted barley, which has been mashed, heated with water and fermented into a crude type of beer, which is then fed into steel or plastic vats filled with beech shavings. Acetobacter is added to convert the alcohol to acetic acid. The raw malt vinegar is filtered, matured and then coloured with caramel for a brown coloured vinegar. Malt vinegar is used fr pickling (especially walnuts and in making Worcestershire sauce.
Dowell, P., Bailey, A. (1980) The Book of Ingredients, Dorling Kindersley. ISBN 0718119150.