Physical refining requires more severe conditions than chemical refining, as the initial free fatty acid content is considerably higher. It is important to make a distinction between odoriferous components already present in the crude oil and odoriferous components formed by thermal degradation of flavor precursors. Removal of the first group of compounds is quite similar to free fatty acid stripping and can be considered not as nearly time dependent. However, perfect deodorization is more complex and minimum time is demanded to avoid some flavor precursors remaining in the deodorized oil resulting in the development of off flavors during storage.