Operating Variables
Deodorization conditions depend upon the particular oil type, the oil quality, and the refining system used. A shift in refining technology toward physical refining where the FFA is removed exclusively by steam distillation requires more severe conditions than do chemically refined oils. With chemical refining, most of the FFA content has been neutralized before deodorization. Physically refined oils have FFA contents between 1.0 and 5.0% compared to 0.05 to 0.1% for chemically refined oils. The steam distillation requirements for both physical and chemically refined oils can be achieved by altering one or more of the operating variables. The four interrelated operating variables that influence deodorized oil quality are vacuum, temperature, stripping-steam rate, and holding time at deodorization temperatures