Short spacings and polymorphic forms of natural and commercial solid fats: A review

Short spacings refer to the cross sectional packing of the hydrocarbon chains. They are independent of chain length. Short spacings are widely used for characterizing the various polymorphic forms. Fats can crystallize into four polymorphic forms, i.e., sub‐α, α, β′ and β. These polymorphic forms differ in their chain packing and thermal stability. The β′ form is also known to exhibit several intermediate polymorphic forms. The nomenclature for the polymorphic forms has generated a great deal of confusion over the years. Several researchers have reported on the polymorphic forms of pure triglycerides. Similar polymorphs have sometimes been described by different names. Currently, the nomenclature proposed by Larsson [Larsson, K., Acta Chem. Scand. 20:2256 (1966)] is being widely used. Much of the earlier work on polymorphism has been obtained by studying simple purified substances. The listing of short spacings for natural and commercial fats presented in this paper will be beneficial to researchers working in this field.