Month: May 2016

The Magic of Bread

Bread is a good thing. I regard it as the necessity on the dinner table and one of the indispensable developments and creations in the food industry. Bread can be eaten alone as breakfast or combined to other dishes to balance the flavor. As a big fan of bread, I think it may be a good idea to talk about the process of making bread and its charm in such a tender and beautiful spring day.

Bread-making contains four simple steps, but the chemistry behind it looks more complex than the straightforward recipe. Firstly, mix three of the four different ingredients: flour, water, and salt. This dough is the foundation of the bread. Then, knead the dough. The starch in flour will be converted into glucose, which acts as the food for yeast. The third step is to add the yeast and wait for the fermentation. Although simple and boring, kneading and fermentation are essential in bread-making because they determine the taste and how puffy your final product is. Finally, bake the well-fermented bread into the oven and wait for the magic, brown, yummy bread!

One reason I like bread is that it smells tasty. The aroma spreads out through the oven and stimulates my taste buds. I just cannot wait to have my wonderful accomplishment! But, wait a minute, where does the aroma come from…hmm, an interesting question to think about. There are three sources that where the aroma comes from: ingredients, fermentation, and baking. It is obvious that the ingredients you use in the bread can determine its smell; for example, you will add chocolates into the bread if you want to make chocolate bread, and chocolates bring the smell of themselves into the bread. However, this in only a minor contributor compared to the later chemicals. During the fermentation, yeast uses sugars created by the enzyme to produces chemical compounds, and the aroma is the byproduct of these productions. Maillard reactions happened in the baking process. It has two classes, between sugars and amino acids, and sugar caramelisation reaction. Both reactions create the brown color in the crust and produce the aroma and taste of the bread.

It is clear to learn about bread by the combination of bread-making process and its aromatic sources. Although each step in the process is important, the one that contributes the most to the smell is the baking process. Not surprisingly, crust and crumb contain different chemicals. For the crust, maltol and isomaltol are derived from the caramelisation reaction of sugar. They produce the malty aromas, which corresponds to their names. Another significant chemical called 2-acetyl-1-pyrroline (2AP) is formed in the Maillard reaction. It has a roasted and cracker-like smell. A higher level of yeast in the bread results in more 2AP. These compounds create not only the aroma but the brown coloration as well. On the other hand, crumb has lower levels of compounds I mentioned above. Furthermore, it has its own aroma sources and, strangely enough, they actually mimic the smell of other stuff. In the Maillard reaction, (E)-2-nonenal and (E,Z)-2,6-nonadienal have the smell of cucumber. (E)-2-nonenal is related to the odor of human as age increases. 2,3-butanedione, which is also known as diacetyl, creates the scent of potato. Even though all those compounds have their weird smell alone, the combination of them produces the smell of bread. Isn’t this cool! These compounds are the major but small parts of all the smell resources. The final aroma consists of a large collection of all chemical compounds formed in the bread. Overall, different types of bread have various compounds and create their unique aromas.

Food is for the enjoyment of its taste and appearance, but more importantly, food supports our health. A lot of people like bread and it is a good thing to me at least. However, we need to control and pay attention to the amount we take in per day. Fermentation is good for health but manufacturers put too much sugar and oil to ensure the flavor. Eating too much bread can cause obesity or even cardiovascular diseases. Hope you enjoy the yummy food and also, take care of yourself~

Cites:

Baking Bread: The Chemistry of Bread-Making

Aroma Chemistry – The Smell of Freshly-Baked Bread