Vegetable oils are obtained by pressing either cold or heated ground kernels or crushed whole fruit, such as olives. The first oil collected from cold pressing is called virgin oil. The remaining oil in the oil cake (seed and fruit residue after pressing) is extracted using heat and a solvent. Finally, refining produces pure oil with a neutral flavour and smell.
Animal fat from pork, beef and poultry is obtained from melting fatty pieces of different types of meat. Any remaining meat which has roasted under the effect of the heat is removed by filtering.
The production of fish oil begins by cooking and pressing whole fish. After that, the extraction process is very similar to that of vegetable oils. The refining of fish oil involves a series of physical and chemical treatments, the final stage being the removal of odorous products.
Butter is an animal fat obtained from milk. It is the result of churning cream, the fatty portion of milk. Churning involves breaking up the fat globules in the cream to form tiny droplets. The fat released then clumps together into grains of butter and tiny water droplets are dispersed in the fatty mass.
Margarine is an emulsion similar to butter, which consists of a mass of fat (fatty phase) containing tiny water droplets (aqueous phase). It is produced from a mixture of oil and fat. Fat-soluble vitamins and lecithin are added to this fatty portion, acting as a binding agent for the emulsion. The aqueous phase contains skimmed milk, water and salt. To obtain an emulsion, the fatty phase and the aqueous phase are vigorously beaten together while simultaneously cooled.