Bread Better: The Yoga Mat Chemical

So far in this series, we've talked about how a basic loaf of bread is emerges from the combination of four simple ingredients. However, modern bread has more than four ingredients in it – there's a long list of other ingredients, some of which are borderline unpronounceable. And that has led to a lot of anxiety: whether it comes to GMOs, preservatives, or additives described as “artificial,” the majority of the American public can be described as skeptical of the food industry's practices. Something similar recently occurred at Subway, where a blogger who calls herself the Food Babe found out that a certain chemical used in the manufacture of yoga mats is also found in their bread and then mounted a successful campaign to pressure Subway to remove it. But what is this chemical, what was it doing in Subway's bread to begin with, and were we ever in danger?

When the controversy came up in the news, the yoga mat chemical's real name was mentioned in the same breath, and it's an impressive collection of syllables: azodicarbonamide. Still, just because something has an intimidating name doesn't necessarily mean it's a problem. Plenty of people regularly put (2R,3R,4S,5S,6R)-2-[(2S,3S,4S,5R)-3,4-dihydroxy-2,5-bis(hydroxymethyl)oxolan-2-yl]oxy-6-(hydroxymethyl)oxane-3,4,5-triol in their coffee, and that doesn't even look like a real word, much less something you want in your body. This, however, is just the official name for sucrose – table sugar. The people who designed the conventions around naming chemicals did so less for the sake of poets and more so that anyone who understands how the system works can reproduce a chemical's structure from its name.

The structural formula of azodicarbonamide. Source.

The structural formula of azodicarbonamide. Source.

Azodicarbonamide, in comparison, is fairly simple: the azo- prefix means there's two nitrogens sharing a double bond. A carbonamide is a carbon double bonded to an oxygen and to an amine (NH2) group. Di- means there's there's two of them. So the name tells us that the compound only contains carbon, nitrogen, and oxygen, and how those elements are arranged.

Azodicarbonamide belongs to a class of chemicals known as dough conditioners. Conditioners play several different roles in breadmaking, but their purpose revolves around reducing the industrial processing time from kernel of wheat to loaf of bread. They can be split into three major categories: bleaching agents, oxidizing agents, and reducing agents.

Each of these functions is related to the presence of sulfur in wheat proteins. Sulfur plays an important role in the formation of gluten, which results from what's called a disulfide bridge, a strong linkage between the glutenin and gliadin molecules in wheat that allows the large gluten complexes to form and stay stable. This sulfur, however, can give freshly milled wheat a yellow color that's considered undesirable. While it will gradually fade over time as the sulfur is exposed to oxygen, industrial bakeries with short turnaround times will use bleaching agents which, as the name suggests, make dough whiter more quickly.

An image of flour milled by the Fosterton Farm in Australia shows the yellowish cast of reduced sulfur compounds. Source

An image of flour milled by the Fosterton Farm in Australia shows the yellowish cast of reduced sulfur compounds. Source

The yellow sulfur in freshly milled flour is also bad at forming those disulfide bridges, meaning that un-aged flour will result in weaker rises and a denser final product. To counteract this, processers will add oxidizing agents. On the other hand, if a softer product, such as a sweet bread or pastry is desired instead, reducing agents will undo the work of oxidizing agents, again weakening the gluten and creating a less chewy loaf.

For a long time in commercial baking, the go-to bleaching agent was potassium bromate. In its pure form, potassium bromate is obnoxious stuff – its abilities to oxidize things are not limited to flour, and it will happily attack aluminum, copper, and humans. Ingestion of potassium bromate can cause kidney failure and respiratory problems. It was thought that potassium bromate added to flour decomposed to undetectable levels in the baking process, but further research into its role as a carcinogen and concerns that it could persist in levels high enough to harm humans have lead to potassium bromate being phased out of flour production.

You may be feeling a little deja vu now, because where potassium bromate was removed, it was frequently replaced with azodicarbonamide, which is also a respiratory hazard in its pure form, also thought to decompose into harmless byproducts (in this case, nitrogen gas and carbon monoxide), and also capable of producing carcinogens (see further reading, below).

Nonetheless, azodicarbonamide is clearly the lesser of the two evils in this scenario; the carcinogenic substance it can produce, ethyl carbamate, is already present in breads as a byproduct of yeast fermentation and is thus also found in places like soy sauce and beer, and it's not dangerous in the low levels of intake we all experience.

So were azodicarbonamide's critics making a mountain out of a molehill? The problem with Food Babe's criticism (and the mountain of news stories it spawned) is that it's easy to dismiss as empty demagoguery of the same genre as the email forwards describing Coca-Cola's alleged effectiveness as a toilet cleaner. At the same time, however, even if azodicarbonamide poses no or low risk to consumers, there have been problems in the past with workers experiencing health problems as a result of improper safety protocols.

Consequently, it should be reasonable to demand that commercial manufacturers continue to search for and implement safer alternatives to problematic ingredients and manufacturing practices. In this case, Subway replaced azodicarbonamide with ascorbic acid, a form of vitamin C. The only drawback to using ascorbic acid over more powerful dough conditioners is that it requires the addition of helper enzymes, which makes it more expensive to use, although the premium per loaf of bread would be small given how little dough conditioner is needed to produce the desired results.

Of course, delicious bread has been produced for centuries without the use of any dough conditioners, but it takes much more time to do so and the product can be less consistent. Whether or not the additional expense of traditionally made bread is worth it is a matter of culture and personal preferences rather than policy.

For Further Reading

More on dough conditioners

FDA FAQ on Azodicarbonamide

The contribution of azodicarbonamide to ethyl carbamate formation in bread and beer
M.J. Dennis , R.C. Massey , R. Ginn , P. Willetts , C. Crews , I. Parker 
Food Additives & Contaminants 
Vol. 14, Iss. 1, 1997