We are all familiar with the delicious characteristic taste of butter.  Interestingly, there are two chemical compounds naturally found in butter that are responsible for this taste: acetoin and diacetyl.  Because of this, manufacturers often add these chemicals to processed foods to give them an artificial butter flavour.  Diacetyl is a natural byproduct of fermentation.
It has recently come into the spotlight because it was implicated as having a role in the development of a few different diseases, namely popcorn worker’s lung (bronchiolitis obliterans), and Alzheimer’s Disease.

Food and Beverage Use

Diacetyl is used to create a butter-like taste in products that are marketed as butter-flavoured like margarines, processed foods and oil based products. It is also used in beverages since the diacetyl increases the slippery sensation on drinks in the mouth and contributes to butterscotch and other similarly buttery flavours. Diacetyl is a natural by-product of the fermentation process in certain alcoholic beverages, mainly wine and beer. Sometimes, the creation of diacetyl is promoted by brewers and in other cases it will be deliberately removed by yeast absorption through the use of an extra warming period. The taste of the final product will be affected by the removal or promotion of diacetyl.

Popcorn Worker’s Lung

In the mid-2000’s it became apparent that workers in several factories manufacturing artificial popcorn flavouring were coming down with serious lung conditions.  Prolonged exposure to the inhalation of diacetyl vapours, has been shown to cause bronchiolitis obliterans.  In this disease, the normal lung tissue becomes inflamed and scarred, which eventually completely obstructs the airways.  At this time, the only known cure for this disease is a lung transplant.  In 2009 and 2010 legislation was put forward to implement safety measures into diacetyl manufacturing to protect the factory workers.  Many manufacturers are also voluntarily reducing their use of diacetyl in products, especially heated products like microwave popcorn, to help prevent exposure to consumers.  When the popcorn is microwaved, the diacetyl becomes vapourized, and can be released in the steam of the freshly popped bag.

Alzheimer’s Disease

There is some preliminary evidence that diacetyl may also contribute to the progression of Alzheimer’s Disease.  It was found that in a test tube, diacetyl increases beta-amyloid aggregation, one of the processes linked to the progressive loss of neurons in the brain.  For more information, please see our Alzheimer’s Disease article.

How can I avoid diacetyl exposure?

The only proven health risk of diacetyl is its inhalation over time.  If you simply MUST have your butter flavoured microwave popcorn, then be sure to avoid inhaling the fumes, especially when it is fresh and steaming.  Make freshly popped popcorn and add your own butter instead to completely avoid the risk.  There is very little evidence that eating diacetyl is a health concern.  Further research is required to be sure. The simplest way to avoid diacetyl exposure is to avoid processed foods that contain artificial butter flavouring, and fermented alcoholic beverages like beer and wine that have not been fully fermented to remove excess diacetyl.