Widely distributed in foodstuffs in trace amts., presumably as bacterial decarboxylation prod. of proline. Present in bread, milk, cheese, carrots, celery stalks, beer, spirits, coffee, caviar and fatty fish. Flavouring agent Pyrrolidine is a clear liquid with an unpleasant odor that is ammoniacal, fishy, shellfish-like and seaweed-like. Pyrrolidine is found naturally in the leaves of tobacco and carrot. The pyrrolidine ring structure is present in numerous natural alkaloids such as nicotine and hygrine. It is found in many pharmaceutical drugs such as procyclidine and bepridil. It also forms the basis for the racetam compounds (e.g. piracetam, aniracetam). A pyrrolidine ring is the central structure of the amino acids proline and hydroxyproline. (Wikipedia)