Polymorphism

It is the ability to crystallize under 3 crystalline forms : α , β' , β .

• Crystals α, with hexagonal form, has little arrangements of hydrocarbon chains, so its low melting point.
• Crystals β', with orthorhombic form, has more dense arrangements of hydrocarbon chains.
• Crystals β, with triclinic form, has very dense arrangements of hydrocarbon chains, so its melting point very high.

Polymorphism has a considerable influence on the fluidity, texture and appearance of the products. In case of oils, they generally crystallize first under α form, which is unstable and evaluates rapidly to β' form, than slowly to β form. In case of palm oil, where the triglycerides are symmetric, the transition αβ ' β is easier, however the last form is more difficult to obtain.

The good separation between olein and stearin is obtained with crystals in mainly β' form.

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