Following extraction and regardless of the process described above, the end product will generally be a rather impure biolipid that contains undesirable contents such as FFAs, tocopherols, waxes and possibly phosphatides. The latter, if not removed before storage, will produce a thick gum over time. Gums are formed when the biolipid absorbs water, which causes some of the phosphatides (such as phosphocholine) to become hydrated and thereby lipid insoluble. Accordingly, hydrating the gums and removing the hydrated gums from the oil before storage can prevent the formation of a gum deposit. This treat­ment is called water degumming and involves the addi­tion of water at 60—90 °C before the phase is separated. An optimum temperature is sought, as it must not be so high as to increase the solubility of phosphatides in oil. A temperature that is too low will increase the viscosity, making phase separation more difficult. It is never applied to fruit oils like olive oil and palm oil, since these oils have already had considerable water contact during their pro­duction. The removal of nonhydratable phosphatides (such as phosphatidic acid) requires the addition of an acid, usually citric or phosphoric, which will form a sludge that can be easily removed (Dijkstra and Van Opstal, 1989). This addition of acid is proportional to the amount of phosphorous already contained in the sample. In addi­tion, this acid also reduces any iron salts and decreases chlorophyll contamination. Enzymatic degumming fo­cuses on the use of lipases, which convert nonhydratable lipids to more hydratable forms. Although the process has been tried at a larger scale for 20 years, it has not made the advancement toward widespread use (Dijkstra, 2010; Yang et al., 2008).