Diacetyl
From Wikipedia, the free encyclopedia
| Diacetyl | |
|---|---|
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| General | |
| Systematic name | 2,3-butanedione |
| Other names | diacetyl, biacetyl |
| Molecular formula | C4H6O2 |
| SMILES CC(=O)C(C)=O | ? |
| Molar mass | 86.09 g/mol |
| Appearance | liquid |
| CAS number | [431-03-8] |
| Properties | |
| Density and phase | ? g/cm³, ? |
| Solubility in water | ? g/100 ml (?°C) |
| Melting point | -2 to -4 °C |
| Boiling point | 88 °C |
| Viscosity | ? cP at ?°C |
| Hazards | |
| MSDS | External MSDS |
| Main hazards | Harmful, flammable |
| NFPA 704 | |
| Flash point | ?°C |
| R/S statement | R: R10 R22 R36 R37 R38 S: S9 S16 S33 |
| RTECS number | ? |
| Related compounds | |
| Related compounds | ? |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
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Diacetyl (IUPAC systematic name: butanedione or 2,3-butanedione) is a natural byproduct of fermentation. It is a vicinal diketone (two C=O groups, side-by-side) with the molecular formula C4H6O2.
At low levels in alcoholic beverages, it contributes a slipperiness to the feel of the beer or wine in the mouth. As levels increase, it imparts a buttery or butterscotch flavor.
It is produced during fermentation as a byproduct of valine synthesis. During this synthesis yeast produces α-acetolactate, which escapes the cell and is spontaneously decarboxylated into diacetyl. The yeast then adsorbs the diacetyl, and oxidizes the ketone groups to form acetoin and 2,3-buntanediol, relatively flavorless compounds.
Beer sometimes undergoes a diacetyl rest, which entails elevating temperature slightly for two or three days after fermentation is complete, to allow the yeast to absorb the diacetyl it produced earlier in the fermentation cycle. The makers of some wines, such as chardonnay, deliberately promote the production of diacetyl because of the feel and flavors it imparts. It is present in many California chardonnays known as "Butter Bombs," although there is a growing trend back toward the more traditional French styles.
The United States National Institute for Occupational Safety and Health has suggested that diacetyl, when used in artificial butter flavoring (as used in microwave popcorn), may be hazardous when heated and inhaled over a long period. Workers in several factories that manufacture artificial butter flavoring have been diagnosed with bronchiolitis obliterans, a rare and serious disease of the lungs. The cases found have been mainly in young, healthy, non-smoking males. There is no cure for bronchiolitis obliterans; treatment is a lung transplant.
While several authorities have called the disease "Popcorn Worker's Lung," a more accurate term suggested by other doctors may be more appropriate, since the disease can occur in any industry working with diacetyl: diacetyl-induced bronchiolitis obliterans. After the workers filed a lawsuit against the manufacturers, the Environmental Protection Agency began an investigation into the chemical properties of microwave popcorn butter flavoring. On July 19, 2005, jurors awarded a popcorn plant worker in Missouri $2.7 million for his claim of diacetyl-induced respiratory problems.
On July 26, 2006, the International Brotherhood of Teamsters and the United Food and Commercial Workers petitioned the U.S. Occupational Safety and Health Administration to promulgate an emergency temporary standard to protect workers from the deleterious health effects of inhaling diacetyl vapors. The petition was followed by a letter of support signed by more than thirty prominent scientists. The matter is under consideration.
[edit] See also
[edit] External links
- NIOSH Alert: Preventing Lung Disease and Workers who Use or Make Flavorings
- Harber, Philip; Saechao, Kaochoy; & Boomus, Catherine. Diacetyl-induced lung disease. Toxicological Reviews 2006;vol 25(4):261-72.
- A Case of Regulatory Failure - Popcorn Workers Lung, from www.defendingscience.org.
- Scientists Urge Secretary of Labor to Protect Workers from Diacetyl, a press release from defendingscience.org. Links to studies on the health effects of diacetyl, and to a variety of related documents including the recent OSHA petition and the scientists' letter of support may be found here.
