描述
Constituent of butter and produced by many microorganisms [DFC]
Acetoin is a colorless or pale yellow to green yellow liquid with a pleasant, buttery odor. Acetoin is used as an external energy store by a number of fermentive bacteria. Acetoin, along with diacetyl, is one of the compounds giving butter its characteristic flavor. Acetoin is used as a food flavoring (in baked goods) and a fragrance. It can be found in apples, butter, yogurt, asparagus, black currants, blackberry, wheat, broccoli, brussels sprouts, cantaloupe. [Wikipedia].