Triacylglycerol polymorphism is a stereochemical phenomenon



Unit-cell stereochemistry for triacylglycerols in β′ (beta prime here and throughout) and β forms has been compared using data from studies of phase behavior for enantiomeric mixtures and space group determinations. The β′ form has a unit cell containing one stereoisomer and the β form has a unit cell containing both stereoisomers. As a result, the crystallization and polymorphic behavior for achiral, chiral-racemic, and chiral-enantiopure triacylglycerols is remarkably different. Accordingly, any plausible mechanism for TAG polymorphism must take unit cell stereochemistry into account.