Final answer:
The number of double bonds in a fatty acid affects the melting point, oxidative stability, and atherosclerosis risk. Double bonds decrease the melting point and oxidative stability, while increasing the risk of atherosclerosis.
Step-by-step explanation:
The number of double bonds in a fatty acid can affect several properties.
First, the melting point of a fatty acid is decreased by the presence of double bonds, especially cis-double bonds, because they disrupt the packing of fatty acid molecules, resulting in less contact area between them and weaker intermolecular forces.
This is the reason why vegetable oils, which have more cis-double bonds, remain liquid at room temperature, while animal fats, which have fewer double bonds, are solid at room temperature.
Second, the oxidative stability of fats is decreased by the presence of double bonds.
Double bonds in fatty acids are susceptible to oxidation, which can lead to rancidity and the production of harmful free radicals.
Third, the risk of atherosclerosis (hardening of the arteries) is influenced by the number of double bonds in a fatty acid.
Fatty acids with more double bonds, such as polyunsaturated fats, are associated with a lower risk of atherosclerosis compared to saturated fats.