Chemicals in My Food

John Coupland is a Professor of Food Science at Penn State. His research program is on the physical properties of foods, in particular fats and oils. He teaches undergraduate Food Chemistry and graduate level Food Chemistry and Food Physical Chemistry. This is about that.

Feb 14

So what is azodicarbonamide actually doing in bread?

With all the media attention on the yoga mat chemical in bread there has been remarkably little written on what azodicarbonamide is actually used for. This is a brief description of the chemistry of the ingredient. Also in my recent piece on the Food Babe’s campaign, I treated concerns about the safety of this ingredient much too lightly and this is an attempt to put that right.

When you knead flour and water to make dough you are allowing individual wheat proteins to bond together to form an elastic network - gluten. The gluten will trap the gas bubbles formed by yeast fermentation and give the dough and the bread its body.  The important connections between proteins are largely disulfide bonds formed by the oxidation of two thiol groups on adjacent proteins.

Azodicarbonamide acts as a dough improver by chemically oxidizing thiol groups and rapidly forming the gluten network.  It can also oxidize other flour components, including pigments, and is sometimes described as a bleach. The main benefit azodocarbomide offers to consumers is it reduces costs by making a better dough from a poorer quality (cheaper!) flour. There are several alternative dough improvers.

When azodicarbonamide oxidizes thiol groups, it is reduced to biurea which is in turn rapidly excreted from the body and poses no health risk. Directly consumed azodicarbonamide is oxidized in a similar manner inside the body and also is not believed to be a toxicity risk under these circumstances. However small amounts of semicarbazide and urethane have been shown to form from azodicarbonamide breakdown during baking and these compounds may pose a health risk.  In particular urethane is listed as a carcinogen under California Prop 65.  The real question is whether these tiny concentrations in bread are toxicologically significant. At the moment CSPI say the risks are real and the additive should be banned while FDA says its safe and permits its use at up to 45 ppm in dough. 

References
Cañas, B.; Diachenko, G. W.; Nyman, P. J. Food Addit. Contam. 1997, 14, 89.
Dennis, M.; Massey, R. C.; Ginn, R.; Willetts, P.; Crews, C.; Parker, I. Food Addit. Contam. 199714, 101.
Joye, I. J.; Lagrain, B.; Delcour, J. A. J. Cereal Sci. 2009, 50, 11.
Noonan, G. O.; Begley, T. H.; Dachenko, G. W. J. Agric. Food Chem. 2008, 56, 2064.