Diacetyl (butter flavouring)

Diacetyl, also known as 2,3‑butanedione, is a naturally occurring organic compound with the chemical formula C₄H₆O₂. At room temperature, it is a yellow‑green liquid with a distinct buttery smell and taste. It is highly volatile and soluble in water, making it easily detectable by the human sense of smell.

Origin

Diacetyl occurs naturally as a by‑product of fermentation, especially in dairy products such as butter and cheese, and in alcoholic beverages such as beer and wine. Industrially, diacetyl can be synthesised by chemical processes or biotechnological methods involving microbial fermentation. Synthetic production usually involves the catalytic dehydrogenation of 2,3‑butanediol.

Characteristics and food applications

Diacetyl is used in the food industry for several reasons due to its unique properties:

• Flavor enhancement: It imparts a rich buttery flavor that is attractive in a variety of food products.
• Aroma: Its strong buttery aroma is used to enhance the sensory appeal of foods.
• Efficacy at low concentration: only a small amount is needed to achieve the desired taste and aroma.
• Versatility: it can be used in a wide range of food products, from baked goods to snacks and beverages.

Use in ultra‑processed foods

In ultra‑processed foods, diacetyl is used for its strong flavour and aroma properties. Here are some specific uses:

• Butter‑flavored popcorn: Diacetyl is often added to microwave popcorn to give it a buttery flavor that mimics freshly made popcorn with melted butter.
• Baked goods: Diacetyl is added to pastries, cakes and cookies to enhance the buttery taste and make these products more appealing to consumers.
• Snacks: Many savoury snacks, such as crisps and crackers, contain diacetyl to impart a rich buttery flavour.
• Margarine and butter substitutes: Diacetyl helps these products closely mimic the taste of real butter.
• Dairy products: Diacetyl is added to some dairy products to intensify the buttery flavour, especially in low‑fat or processed cheese.
• Beverages: Some alcoholic and non‑alcoholic beverages may contain diacetyl to enhance their flavour profile.

Effects on human health

Although diacetyl is generally recognized as safe for use in food (GRAS) by the FDA, there are significant health concerns associated with its inhalation, particularly in occupational settings.

• Respiratory problems: Inhalation of diacetyl fumes has been linked to a serious lung disease known as bronchiolitis obliterans, also referred to as "popcorn lung". This condition causes severe and irreversible damage to the small airways in the lungs, leading to coughing, wheezing and shortness of breath.
• Occupational hazards: Workers in industries where diacetyl is used, such as flavouring and food production, are at higher risk of developing respiratory problems if appropriate safety measures are not in place.
• Regulatory action: In light of these health risks, there have been calls for stricter regulations and the use of safer alternatives in food production and flavouring processes.

Sources

1. U.S. Food and Drug Administration. (2021). Diacetyl. Retrieved from FDA.gov.
2. Occupational Safety and Health Administration.(n.d.). flavorings‑related lung disease. Retrieved July 10, 2024, from https://www.osha.gov/flavorings‑related‑lung‑disease
3. Dinu, V., Kilic, A., Wang, Q. et al. Policy, toxicology and physicochemical considerations on the inhalation of high concentrations of food flavour. npj Sci Food 4, 15 (2020). https://doi.org/10,1038/s41538‑020‑00075‑y
4. Clark, S. F., & Winter, C. K. (2015). Health effects of diacetyl: a review of toxicologic data. Food Science and Technology, 67, 87‑95. DOI: 10,1016/j.foodcont.2015,05.012.