Deodorization is the removal or concealment of an unpleasant smell from a product. In edible oil refining it is a defining step: superheated steam under vacuum strips away the volatile compounds behind off-odours and off-flavours, yielding the bland, neutral oils consumers expect. The same steam carries off free fatty acids, aldehydes and traces of pesticide residues. Operators must balance thoroughness against heat damage that destroys tocopherols and can form trans fats, making deodorizer control one of the most skill-intensive jobs in the refinery.