Physical Refining of Edible Oils and Fats

Crude oils obtained by oilseed processing have to be refined before the consumption in order toremove undesirable accompanying substances. The traditional alkali refining is often replaced by physicalrefining in which the use of chemicals is reduced. The most widely used method is steam refining. The crude oilquality is very important in order to obtain high quality refined oil. Furthermore, the oil should be efficientlydegummed to remove phospholipids as well as heavy metals and bleached to remove pigments. The mostimportant step consists of the application of superheated steam under low pressure and at temperatures higherthan ۲۲۰ °C. Both free fatty acids and objectionable volatiles, formed by cleavage of lipid oxidation products, areremoved. A disadvantage is the partial loss of tocopherols. Side reactions, particularly isomerization ofpolyunsaturated fatty acids, should be minimized. The quality of physically re- fined oil is close to that of alkalirefined oils, but losses of neutral oil are lower and the environment is less polluted. Among other methods ofphysical refining the application of selective membranes is promising.

کلیدواژه ها:

Bleaching ، Degumming ، Edible Oils ، Membrane Refining ، Physical Refining ، Steam Refining