By: Khushi Gupta
Many people think that experimenting with science is only possible in a lab with high-tech gear and equipment, and don’t realize that even day-to-day activities incorporate science in them. For example, whenever you cook or bake, you are a chemist! From mixing together eggs and flour to baking the dough in the oven, there are many chemical reactions happening. Not only that, but making different foods is an integral part of being human. It is not only practical but also derives cultural, social, and personal meanings from bridging different cultures or having a family recipe passed down for generations.
Take caramel, for example—caramelization is a complex process that is not fully understood even today! It is a Maillard reaction, a type of non-enzymatic browning, which occurs when high concentrations of carbohydrates are heated above a certain temperature. The temperature varies depending on what type of sugar is used. Caramelization is not a single reaction but a process that undergoes many steps. Here’s an overview of what happens during this process. First, there is the melting of sugar at high temperatures and right after, boiling (foaming). This causes sucrose inversion, or break down, into fructose and glucose. Then, there is condensation with intramolecular bonding and the isomerization of aldoses to ketoses. There are then dehydration and fragmentation reactions, followed by the polymer formation.
Proteins are the “meat” of chemical reactions. There are 4 complex layers in proteins: the primary structure (the amino-acid composition as well as the intramolecular bonds between them), the secondary structure, the tertiary structure, and the overall 3D shape. When protein structures such as these undergo denaturation, a process that happens in cooking which breaks down these complex layers, the proteins revert to their primary or secondary layer. When heating the proteins, the molecules move around a lot which causes the intramolecular bonds to be broken, allowing the protein to denature which changes the food textures. Denaturation essentially makes them easier to break down chemically and mechanically, which is why chewing cooked meat produces more calories than raw meat. Proteins are long, spiraling chains, but there are 2 main types: fibrous and globular. Fibrous proteins have their spiral chains folded to form long, thin shapes. They are strong and generally insoluble in water. Globular proteins are folded into spherical shapes and are usually soluble in water. Examples of them include hemoglobin.
Questions:
1. What type of reaction is caramelization?
Caramelization is a type of Maillard reaction. Maillard reactions are chemical reactions where sugars and proteins are reduced by heat, which gives the browned food that distinct flavor.
2. What are the three types of pH levels?
The three levels are acidic, alkaline, and neutral. Using a pH scale, one can determine which type it is based upon the number 7. To determine what the food is, you can use the pH Scale which runs from 0 to 14. A food lower than 7 is acidic, higher is alkaline and 7 is neutral. The further away of 7, the more alkaline or acidic the food is. An example of an acidic food is yogurt (around 4-4.5) and lemon juice (2-3). The range is there since there can be deviations in similar foods, with one lemon being 2.5 and another being 2.1. The pH value is used to find the lifespan of the food on your shelf, food processes, and affects the taste/flavor. It also is a big indicator of the types of chemical reactions that can happen.
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