butanedione

Butanedione, also known as diacetyl, is a naturally occurring organic compound with the chemical formula C4H6O2. It is a vicinal diketone, meaning it has two ketone functional groups on adjacent carbon atoms. Butanedione is a yellow to green liquid at room temperature and possesses a strong, buttery odor. This characteristic aroma is responsible for its use as a flavoring agent, particularly in artificial butter flavoring.

It is produced naturally by various microorganisms during fermentation processes, including those involved in the production of beer, wine, and yogurt. In brewing, butanedione is a common byproduct and its presence is carefully monitored as excessive amounts can lead to undesirable flavors, often described as "buttery" or "butterscotch." Conversely, in some dairy products, controlled levels contribute to their characteristic flavor profile.

Industrially, butanedione can be synthesized through the oxidation of 2,3-butanediol. Its primary application is in the food industry as an additive to impart buttery flavors to a wide range of products, including margarine, baked goods, popcorn, and confectioneries. However, its use in food products has been a subject of concern due to potential health risks associated with inhalation exposure, particularly in occupational settings where it is used in large quantities. Inhalation of high concentrations of butanedione vapor has been linked to serious respiratory conditions, such as bronchiolitis obliterans, often referred to as "popcorn lung." Due to these concerns, regulatory bodies have established exposure limits for workers handling the substance.