Vinegar is a liquid mainly consisting of acetic acid and water. Vinegar is of many kinds, malt vinegar being one of them. Malt is the term used for germinated dried grains of barley. Once the barley has been malted (which means allowed to sprout) the resulting maltose is brewed into ale which is further fermented until it achieves a light brown color which is called malt vinegar. In layman's terms barley is first malted into alcohol which is further fermented to make vinegar. It has a strong and rich flavor barley taste. It is somewhat nutty and toasty. It is a dark colored liquid.
The main difference between white vinegar and malt vinegar is that white vinegar is purified vinegar. It is made with only acid and water. Malt vinegar, on the other hand, is grain-based vinegar made from malting barley. Malt vinegar is milder and sweeter in taste than white vinegar.
The invention of malt beer trace back to Britain several years ago. Back then it was made by fermenting beer into vinegar. It was then known as 'alegar'. 'Ale' is a type of 'beer' and 'gar' from vinegar.
There are various types of malt vinegar available - dark, light and distilled being the most common ones. The dark one gets its color from added barley or caramel. The light one is pale brown in color. The distilled malt vinegar is colorless with a sharp taste.
Also known as Alegar, it is a traditional seasoning for fish and chips in the UK. It is also used in simple salad dressing mixed with olive oil and fresh herbs.
It is a popular pickling tool especially for walnut pickles. Most English recipes along with traditional English fish and chips use malt vinegar. It is available all year round. In addition to being used as a condiment, this vinegar is also commonly used in chutneys. If you can't get your hand on malt vinegar you could probably substitute it with wine vinegar, cider vinegar, sherry vinegar etc.
Note: Malt vinegar contains gluten and therefore is not suited for people with gluten allergies.