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.
Critical Thinking in an Applied Science Grad Class
Graduate classes should teach critical thinking in the context of a subject. In the humanities they practice their critical thinking by reading literature and arguing about it; trying to tease out the arguments and positions of the various authors. I have never succeeded in making this model work well in my graduate classes in applied science. In my experience, paper discussions tends to either focus on things that aren’t central (e.g., a focus on the statistics of a chemistry paper - important but not what the class is about) or, better, a pained analysis of what the results actually mean. These problems reveal two issues about using literature to teach critical thinking in the sciences.
First, there is a strong focus on “the answer” in science while in the humanities, being sensibly skeptical they will ever to to the truth, are much more interested in the argument. Indeed, it takes a mature scientist to recognize there is always an argument, a chain of logic, between experiment and understanding. The argument is where the critical thinking happens.
Second, even to understand a science paper requires a fairly deep immersion in the field and its methodologies. This is less of an issue in a disciplinary field like engineering or chemistry but in an applied subject like food science the students come from a variety of backgrounds and not much common knowledge can be assumed. Any real discussion of biopolymer gelation requires you know something about mechanical spectroscopy and if your prior experience didn’t teach you that then you can’t add much.
One approach I’ve found much more effective than paper discussions in promoting critical thinking is to ask students to make posters. Before the class session I ask them to read some textbook treatment of the theory. In class I split them into small groups and give each group some related experimental data, perhaps a figure or two from a paper. They have about 20 min in their group to hand-draw a poster that gives a mechanism to explain the data in terms of the theory they have studied. Next they present their poster to the other groups and answer questions. In essence they are engaging with data and forming an argument from it. This approach breaks the unhelpful reverence for the “answer” and forces them to create their own stories within the context of a theoretical framework. Working in a group reduces the embarrassment of not understanding something and gives them a larger set of common knowledge to apply to the problem.
To say that it came thence, is to say that it was received with disfavor; some said that it was heating, others that it injured the chest; some that it disposed persons to apoplexy. Calumny, however, had to give way to truth, and for eighty years this apothegm has been current, “Sugar hurts nothing but the purse.”
Under this impenetrable aegis the use of sugar has increased every day, and no alimentary substance has undergone so many transformations. Many persons like sugar in a pure state, and in hopeless cases the faculty recommend it as a substance which can do no possible harm, and which is not unpleasant. J. A. Brillat Savarin “The Physiology of Taste" (1825). Meditation VI, Section VIII: Sugar
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.
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. 1997, 14, 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.
The Food Babe and Sudden Change in our Food system.
Vani Hari writes and speaks about food and nutrition as “The Food Babe”. On Feb 4th she launched a petition calling on Subway restaurants to remove azodicarbonamide from their bread in the US. By February 6th over 70,000 people had signed and Subway had given way and took steps to remove the ingredient.
This wasn’t a new issue, the Food Babe wrote about azodicarbonamide previously before but those campaigns did not gain traction. This new campaign was based on perceived dishonesty on the part of Subway. “Last week, Michelle Obama, The First Lady of The United States endorsed this company saying every single item on the kid’s menu met the “highest nutrition standards”. This is what broke the camels back.” How a company brands itself has a huge effect on the ingredients they can safely use.
The Food Babe’s argument is framed in terms of the safety of the ingredient but, at best, this point is not well understood. She cites reports of toxicity from azodicarbonamide, but these are associated with its use in plastics manufacturing as a bulk industrial chemical. Low levels of consumed azodicarbonamide appear to be rapidly metabolized and excreted and have no real toxicological issue. There are more substantial concerns with its thermal degradation to semicarbazide during baking but WHO seems to regard these compounds as more of a concern if azodicarbonamide is used in the foamed plastics of used in the rims of the lids of baby food jars. In any case they describe the risk as “very small” with the possible exception of infants eating a lot of bottled baby food. However, the fact that azodicarbonamide is permitted as food additives in some jurisdictions but not in others is taken as evidence that there is something to be feared here.
In my opinion this wasn’t primarily about toxicology but around the inappropriateness of a compound being used in plastics also being used in foods, particularly by a company that made a big deal of being fresh and healthy. “Azodicarbonamide is the same chemical used to make yoga mats…” captured people’s imagination and drove the campaign.
There was no effort by Subway to explain or defend their legal use of an approved ingredient; on Feb 6th there was nothing on their website, nothing on their twitter feed. I would love to have been in their headquarters this week but I can only imagine they saw a threat to their “Eat Fresh” brand and acted instantly. I doubt the people in Subway who know about azodicarbonamide in bread were even consulted in that decision. Absolutely no one seemed interested in what azodicarbonamide does in bread or what it might or should be replaced with.
There are things to learn from this case for food companies and for food activists.
Food companies need to be way more open. Additives always have a purpose and regulatory oversight and manufacturers of consumer foods should proactively explain both. If your product needs an antioxidant to have a reasonable shelf life then tell people what you are using, why and provide links to the data showing it’s safe and legal under the conditions used. You might prefer not to talk about the chemicals in your food but it’s certainly better than watching #yogamat trend on your social media stream!
Activists should continue to aggressively campaign for better food systems, food companies are desperate to appeal to consumer demand and as this case shows they can and will change fast. Campaign smartly though. This campaign was successful not because of a serious consideration of risk but because of the jarring incongruity of a compound being in bread and in plastic. Lots of compounds crop up in lots of places and this is a weak argument for deciding which uses are appropriate. It is I suppose possible that there will be a public health benefit from eliminating this ingredient but not much actual evidence. You could have been talking about labeling, food safety, nutritional quality, health halos, advertising practices…
Edit (2/10): CSPI call attention to urethane as a second toxic breakdown product and recommend avoiding the ingredient.
Edit (2/14): I add more on the chemistry of azodicarbonamide here and also revisit my somewhat glib dismissal of its potential risks.