is the foam, or scum, formed on the top of liquor
(i.e. fermented alcoholic beverages such as beer
, or feedstock for hard liquor
or industrial ethanol distillation
) when fermenting
. It was used to leaven bread
, or set up fermentation in a new batch of liquor. Barm, as a leaven, has also been made from ground millet
combined with must
out of wine-tubs and is sometimes wrongly used in baking as a synonym for a natural leaven
. Various cultures derived from barm, usually Saccharomyces cerevisiae
, became ancestral to most forms of brewer's yeast
and baker's yeast
currently on the market.
In parts of the North of England a barm or barm cake is a common term for a soft, floury bread roll.
"Barmy" is also British slang for "crazy", comparing the foamy texture of barm to the perceived emptiness of such a person's head.
Notes and references