How to remove impurities in oil? In industry, refining equipment is used to remove impurities in edible oil. Refining equipment can remove impurities through degumming, deacidification, decolorization and deodorization. The oil that is filtered, degummed and deacidified is called semi refining. After decolorization, deodorization, winterization and dewaxing, the oil is called refined oil.
(1) Degumming (dephosphorization)
Degumming can remove colloidal impurities in oil, and the process is called degumming. If the content of phospholipid is high in edible oil, it is easy to bubble, smoke and stink when heated. Moreover, the oxidation of phospholipid at high temperature makes the oil brown, which affects the flavor of fried food. Degumming is based on the principle that phospholipids and some proteins are soluble in oil in sewage state, but insoluble in oil after forming hydrate with water. Add hot water or steam into the crude oil, heat the oil and stir it at 50 ℃. The gel soluble impurities will melt into clusters and separate out after sedimentation, so as to remove the gel soluble impurities.
Free fatty acids affect the stability and flavor of oil, and can be removed by adding alkali neutralization, which is called deacidification, also known as alkali refining.
Crude oil contains chlorophyll, carotenoids and other pigments. Chlorophyll is a photosensitizer, which affects the stability of oil, while other pigments affect the appearance of oil. Bleaching is to remove the pigment in oil by clay adsorption.
There are some undesirable odors in oils and fats, which mainly come from the oxidation products of oils and fats. The method of vacuum distillation was used, and citric acid was added to chelate excessive metal ions and inhibit oxidation
After the "six removal process" of refining equipment, all kinds of impurities in the oil are basically removed, but the beneficial substances in peanut oil still exist, which is in line with the national standard of edible oil.
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