Fatty acids that have a double or triple bond (C=C) in their hydrocarbon chain are called unsaturated fatty acids. Humans and mammals cannot form a double bond after the 9th carbon of a fatty acid. So we need to add some unsaturated fatty acids to our diet. This is why linoleic and linolenic acids are called essential fatty acids. Plant-derived unsaturated fatty acids are beneficial for human health. So the lack of nutrients in the body is fulfilled. For example, oleic acid, linoleic acid, linolenic acid etc.
Properties of unsaturated fatty acids
(i) Carbon atoms of unsaturated fatty acids are joined by divalent bonds.
(ii) Its melting point is relatively low.
(iii) It is an essential fatty acid.
(iv) It is high in phytonutrients.
(v) It is liquid at normal temperature (20°C).