Some oils and fats are liquid at room temperature, and even when kept in the fridge, like olive oil and soybean oil. By contrast, other fats have higher melting temperatures: Butter, margarine and animal fats are solid in the fridge. They become soft solids at room temperature, and melt while cooking. Beef with fat. Credit: Michael C. Berch, Wikipedia. What causes this difference in melting temperature? The answer is: Mostly how saturated the chemical bonds in the fat molecule are in hydrogen atoms.
The following illustrations explain why. In the first illustration, seven molecules of completely saturated fats contain only single covalent bonds between the carbon atoms represented as the corners of the zigzag line , and each carbon is bound to two hydrogen atoms, neither of which is shown in the illustration.
These linear molecules are able to come close to each other and create a dense structure, which allows for strong intermolecular interactions. The melting point of such a fat would be high. By contrast, here is an illustration of three unsaturated fat molecules, specifically oleic acid, a main component of olive oil. This fatty acid includes a double covalent bond, represented by a double line:. Consequently, they have to be supplemented through ingestion via the diet and are nutritionally very important.
Omega-3 fatty acid, or alpha-linoleic acid ALA , falls into this category and is one of only two fatty acids known to be essential for humans the other being omega-6 fatty acid, or linoleic acid. These polyunsaturated fatty acids are called omega-3 because the third carbon from the end of the hydrocarbon chain is connected to its neighboring carbon by a double bond. Salmon, trout, and tuna are good sources of omega-3 fatty acids.
Research indicates that omega-3 fatty acids reduce the risk of sudden death from heart attacks, reduce triglycerides in the blood, lower blood pressure, and prevent thrombosis by inhibiting blood clotting. They also reduce inflammation and may help reduce the risk of some cancers in animals. Boundless vets and curates high-quality, openly licensed content from around the Internet. This particular resource used the following sources:. Skip to main content.
Search for:. Lipid Molecules. Learning Objective Differentiate between saturated and unsaturated fatty acids. Key Points Fats provide energy, insulation, and storage of fatty acids for many organisms. Fats may be saturated having single bonds or unsaturated having double bonds. Unsaturated fats may be cis hydrogens in same plane or trans hydrogens in two different planes. Olive oil, a monounsaturated fat, has a single double bond whereas canola oil, a polyunsaturated fat, has more than one double bond.
Unsaturated fats may be cis hydrogens in same plane or trans hydrogens in two different planes. Olive oil, a monounsaturated fat, has a single double bond whereas canola oil, a polyunsaturated fat, has more than one double bond. Omega-3 fatty acid and omega-6 fatty acid are essential for human biological processes, but they must be ingested in the diet because they cannot be synthesized. Key Terms hydrogenation : The chemical reaction of hydrogen with another substance, especially with an unsaturated organic compound, and usually under the influence of temperature, pressure and catalysts.
It contains the functional group carbon-oxygen double bond joined via carbon to another oxygen atom. OH ; characteristic of carboxylic acids.
Glycerol and Fatty Acids A fat molecule consists of two main components: glycerol and fatty acids. Three molecules of water are released in the process. Saturated vs. Unsaturated Fatty Acids Fatty acids may be saturated or unsaturated.
Unsaturated fatty acids have one or more double bonds. Each double bond may be in a cis or trans configuration. In the cis configuration, both hydrogens are on the same side of the hydrocarbon chain. In the trans configuration, the hydrogens are on opposite sides. A cis double bond causes a kink in the chain.
Trans Fats In the food industry, oils are artificially hydrogenated to make them semi-solid and of a consistency desirable for many processed food products. Essential Fatty Acids Essential fatty acids are fatty acids required for biological processes, but not synthesized by the human body. It has three cis double bonds and, as a result, a curved shape. For clarity, the carbons are not shown.
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