Fats are made up of a large number of triglycerides each of which has its own melting point. As the temperature is reduced the different triglycerides become crystalline progressively and the fat acquires a semisolid consistency.

The crystals of most fats and blends can have three different forms called alpha, beta prime and beta and which type will be obtained depends on their composition and also on the processing conditions. The type of crystals needed in margarines shortenings and most other food products is the beta prime because it gives to the products a smoother texture and better creaming properties. By a fortunate coincidence, the major tropical oils, palm, coconut and palm kernel, tend to crystallise and remain for long periods in the beta prime form.

Cocoa butter and CBE fats are exceptional fats because they can crystallise in 7 or more forms and it is vital that the product made from this group of fats (usually chocolate) has the correct crystal forms otherwise it will suffer all sorts of defects. The tempering procedure given to chocolate is entirely for the purpose of producing the correct stable crystal forms in it.