Deodorization is a vacuum-steam distillation process of an oil at an elevated temperature during which FFAs and minute levels of odoriferous materials are removed to obtain a bland and odorless oil. Most vegetable oils retain characteristic undesirable flavors and odors and obtain others during processing. Bleaching imparts an “earthy” flavor and odor, and hydrogenation adds an odor and flavor that can be described only as typical and certainly undesirable. The odoriferous substances are FFAs, aldehydes, ketones, peroxides, alcohols, and other organic compounds.
Additionally, certain carotenoid pigments are destroyed, resulting in a heat bleaching effect. Efficient removal of these substances depends upon their vapor pressure, for a given constituent is a function of the temperature and increases with
the temperature. Deodorization is the last major processing step during which the flavor and odor and many of the stability qualities of an oil can be affected. From this point forward, effort is directed toward retaining the quality that the deodorized oil possesses; therefore, considerable care must be given to the selection, operation, and maintenance of the deodorizer equipment and the operating conditions