How can you tell whether a fat contains primarily saturated or unsaturated fatty acids?

In terms of physically observing it, if the substance is a lions based substance, like oil or margarine, depending on the state, this will inform how well the hydrocarbons can pack together well or not, or will there be bends in the ring preventing the molecules from packing well.

Liquids are unsaturated
Solids are saturated.

C: plants and animals