Chemistry matters, and it is all around us. We know this fact from the previous blogs, right? Currently, we think that one type of chemical might serve similar functions during chemical reactions. However, after reading two articles from Chemical Interest, I noticed that similar chemicals might serve different functions in different foods, and, surprisingly, even different purposes in the same food. Today, I want to focus on some similar chemicals I found in two kinds of food and discuss how these chemicals serve different functions in each of them.
The chemistry of eggs seems to be simple because eggs are very common in people’s kitchen and somewhat easy to cook. However, the chemistry might be much more complex than you thought. The chemistry includes the composition of eggs and chemical reactions that happen during cooking. Another food that I want to talk about in this blog is bread. The bread-making process, which is about the mixing of four ingredients, sounds as simple as the egg-cooking process because they are both straightforward. However, there is also more chemistry to it than meets the eye, as the bread-making process involves more chemistry on a molecular level.
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One of the large molecules within your body that serves essential functions is protein. Both eggs and bread contain protein. In the chemistry of eggs, a range of proteins makes up the major composition of the egg white. Ovalbumin, one type of protein, provides developing chicks with nourishment and blocks the action of digestive enzymes at the same time. Conalbumin or ovatransferrin binds iron atoms tightly in order to ensure a sufficient supply of iron for the developing chick. It also helps prevent infection from bacteria. Ovomucin, one of the most important proteins in the egg white, ensures its gloopy consistency. These facts about proteins in eggs show that protein, one of the major composition in eggs, can supply nourishment and decrease the possibility of the chick’s illness. I would like to apply this information to all other foods; however, similar proteins serve different functions in another food – bread.
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Proteins are major components in flour which is used to make bread. Gluten, which is composed of proteins with huge molecules called glutenins and gliadins, helps make bread. Without water, the flour itself is inert. After adding water to the mixture, proteins interact with each other and line up to form hydrogen bonds and disulfide cross-links between their chains. The process will continue until a giant gluten network is formed throughout the dough. Kneading the dough uncoils these proteins and therefore speeds up the formation of the giant gluten network. In the chemistry of bread-making, proteins serve the function that connects every piece of flour together and helps us make bread more easily. This function provides a huge difference compared to functions served in eggs.
Both eggs and bread have unique smells, but these smells are generated differently in chemistry. One of the most important contributor to the eggy smell is hydrogen sulfide. Proteins that contain sulfur are reacted chemically during cooking, and hydrogen sulfide is formed during the process. The amount of hydrogen sulfide produced is proportional to the time that an egg is cooked. The longer the time, the more the hydrogen sulfide is formed. Therefore, older eggs and spoiled eggs often contain a higher level of hydrogen sulfide and have a greater eggy smell. Two types of chemical reactions contribute towards the smell during baking bread. The first one is Maillard reactions, which happen between sugars and amino acids. These reactions contribute more to the smell. The second one is sugar caramelisation reactions. These reactions help form compounds with aroma and flavor.
Chemistry is complicated in a general sense but fascinating in some ways because one chemical could provide one or more purposes in different reactions. As I proved previously, similar chemicals in different foods could serve different functions. Different types of proteins composed in eggs and flour help the cooking process in different ways. The smell from eggs and bread results from different chemicals and react in different processes. There is a lot more waiting to be discovered. Again, please remember that chemistry is all around us and it really matters.
- Brunning, Andy. “The Chemistry of Eggs & Egg Shells.” Compound Interest. Andy Brunning/Compound Interest., 26 March 2016. Web. 2 May. 2016. < http://www.compoundchem.com/2016/03/26/eggs/>.
- Brunning, Andy. “Baking Bread: The Chemistry of Bread-Making.” Compound Interest. Andy Brunning/Compound Interest., 13 January 2016. Web. 2 May. 2016. < http://www.compoundchem.com/2016/03/26/eggs/>.
- Brunning, Andy. “Aroma Chemistry – The Smell of Freshly-Baked Bread.” Compound Interest. Andy Brunning/Compound Interest., 20 January 2016. Web. 2 May. 2016. < http://www.compoundchem.com/2016/03/26/eggs/>.