You may not realize it, but there is a lot of chemistry behind cooking and the food that we eat.  That is because if you break down the majority of the ingredients that you are cooking with, and ultimately consuming, generally fall within the category of carbohydrates, proteins, and lipids, which are considered as biomolecules. Now, I am not a chef or a nutritionist, so I cannot give you any tips on how to be a better cook or how to make healthier choices. However, I can give you some information on how certain structural characteristics of molecules affect their physical qualities. 

In my organic chemistry course, we include a substantial section on “alkenes”. An alkene is simply an area of a molecule that is characterized by a carbon-carbon double bond.

The presence of an alkene, or the lack thereof, matters when we describe saturated versus unsaturated fats.  If you look at the molecular structure of saturated fats, its carbon chains contain no carbon-carbon double bonds, and therefore, no alkenes. On the other hand, unsaturated fats do contain one or more carbon-carbon double bonds, alkenes, in their carbon chains.

In a typical household, both saturated and unsaturated fats are used daily in cooking. Saturated fats are typically derived from animal products, and the most common example is butter. Other non-animal fats like coconut oil that are solid at room temperature are also composed primarily of saturated fats.

Common unsaturated fats are usually plant-based products, and they are liquid at room temperature. Olive oil that we use for salad dressing, and other common vegetable oils are examples of fats that are mostly made up of unsaturated fats.

You may have already realized this connection, but the presence of the carbon-carbon double bond, an alkene, affects whether a particular type of fat is solid or liquid at room temperature.  

In order to better understand this difference in state, we have to look at how the alkene impacts the overall structure of a fat molecule.  When one or more carbon-carbon bonds are present within the chains of an unsaturated fat molecule, they cause these rigid “kinks”.  Due to these “kinks”, unsaturated fat molecules cannot pack closely together to have a fixed shape, and this is why unsaturated fats are liquid at room temperature. 

In comparison, saturated fats do not contain an alkene in their carbon chains, and this structural characteristic allows them to stack up closely with one another enough to form a solid at room temperature.  

You can convert unsaturated fats into saturated fats via a chemical process called hydrogenation. Hydrogenation adds hydrogen atoms to carbon-carbon double bonds, and this results in the double bonds to become single bonds. Hydrogenation is a common chemical process in making modern-day margarine, a dairy substitute that is primarily composed of vegetable oil. Some of the double bonds present in vegetable oil are converted into single bonds via hydrogenation, which allows some of the “kinks” to disappear and allow the molecules to pack closer together, creating a solid product. 

Think about how incredible this is! Essentially, the presence of a single carbon-carbon double bond affects whether a substance like fats will be a solid or a liquid at room temperature, and understanding chemistry allows us to have these discussions about the things that we encounter in our daily lives.v