Oils and fats consist of complex mixtures of triacylglycerols (TAGs), diacylglycerols (DAGs), free fatty acids and other minor components. The crystallization of TAG mixtures depends on the nature, chain length and saturation/unsaturation characteristics of the TAGs and the interaction of these TAGs with each other. The presence of DAGs further complicates the crystallization and melting behaviour. In most oils which are derived from oilseeds, the effects of DAGs are less conspicuous, being only present in small quantities. Other oils, e.g. sal fat, palm oil and olive oil, contain higher amounts of DAGs. These DAGs consist of fatty acid moieties that reflect those of the TAGs of the oils.