The purpose of oil refining and deacidification is to separate the free fatty acids in crude oil, so as to improve the quality of oil, increase the stability of edible oil, prolong the storage period of oil, and ensure the health of oil. The presence of free fatty acids will adversely affect the storage and quality of oils and fats, and at the same time, when oils and fats contain a large amount of free fatty acids, they will also have an impact on the subsequent processes of decolorization, degumming, and deodorization.
Through the deacidification process, the acid value of the oil can be effectively reduced, thereby improving the quality and safety of the oil. The method of deacidification can be separated by physical or chemical methods. Physical deacidification is mainly to separate free fatty acids, unsaponifiable substances, odor components, etc. in crude oil by conveying vacuum water vapor to crude oil for distillation stripping, which has a high oil yield, will not produce soap feet, and can also obtain high value-added by-product fatty acids, which is suitable for crude oil with high free fatty acid content.
The chemical alkali refining and deacidification process is to synthesize the free fatty acids in the oil by adding lye to the crude oil, so as to achieve the purpose of separation. The advantage of this method is that it can handle a wide range of crude oils, is easy to handle and can achieve a good deacidification effect. However, when the free fatty acids in crude oil are high, the choice of lye deacidification is easy to cause too much loss of neutral oil in the oil, and increase the loss of lye and oil, so it is not suitable for crude oil with high acid value such as rice bran oil.