FRACTIONATION - Introduction

Among the various edible oil and fats modification processes, dry fractionation has gained the most interest in edible oil industry. It is now applied to many kinds of fats and oils such as palm oil, tallow, fish oil, cottonseed oil, sunflower seed oil, palm kernel oil, tallow butter fat and special fats. Dry fractionation is a pure physical and fully reversible process. Thus this replies to the increasing demand of oil processors for more cost efficient, environmental friendly and safer processes.

Dry fractionation separates the high melting triglycerides from low melting triglycerides by crystallization from the melt. It simply consists of a controlled crystallization of melted oil, conducted accordingly to a specific cooling program followed by separation of the solid from the liquid fraction. Apparently, it looks simple, but in practice, this physical process is completed by the fact that the formation of nuclei depends on the foreign particles, agitation, temperature, triglycerides composition and the type of pre-treatment followed by the oil and fats.

Crystallization is a 3 step process: controlled cooling of the melt, nucleation and crystal growth. The shape and size of the crystals are determined by the way the lipid material is cooled and agitated.