How does increasing saturation levels in fatty acids affect their melting temperature?

Increasing saturation levels in fatty acids directly affects their melting temperature by leading to a higher melting temperature. Saturated fatty acids do not contain double bonds between carbon atoms, which allows them to pack closely together in a solid structure. This tight packing results in stronger van der Waals forces among the fatty acid chains, which require more thermal energy to overcome, thus increasing the melting temperature.

In contrast, unsaturated fatty acids contain one or more double bonds that introduce kinks in their molecular structure, preventing them from packing tightly. This results in weaker intermolecular forces and consequently a lower melting temperature. Similarly, the fluidity of fatty acids is affected by saturation; saturated fats tend to be more solid at room temperature, while unsaturated fats are usually liquid, further illustrating the trend that higher saturation corresponds with increased melting temperatures.