Palm Oil Refining
According to the composition and nature of impurities in palm oil, they can be divided into three categories:
(1) Insoluble solid impurities, such as silt, cake powder, fiber, clay, catalyst, etc.
(2) Peptized impurities, such as free fatty acids, sterols, vitamin E, pigments, vitamins, gossypol, etc.
(3) Volatile impurities, such as water, alcohols, hydrocarbon solvents, odorous substances, etc.
Most impurities are detrimental to the quality and storage safety of palm oil. For example, moisture not only affects oil clarity but also promotes oil hydrolysis and rancidity; free fatty acids affect flavor and promote spoilage; phospholipids can cloud oils and produce black precipitates when heated. Various pigments directly affect the color of the oil, and will also promote the rancidity of the oil; the existence of colloids, sulfur phosphorus compounds, saponins and heavy metal salts makes it difficult to deacidify in subsequent processes such as steam stripping.
(1) Palm oil dephosphorization: remove phospholipids, mucus, resins, proteins, sugars, trace metals, etc. in crude oil, generally using hydration and acid refining methods.
(2) Deacidification of palm oil: use food-grade lye to remove free fatty acids, acid pigments, sulfides, insoluble impurities and trace metals in the oil.
(3) Washing of palm oil: Washing away the saponins and water-soluble impurities remaining in the oil during the deacidification process.
(4) Dehydration of palm oil: the water in the refined oil is removed by heating and vacuum drying.
(5) Decolorization of palm oil: use clay, aluminum silicate, activated carbon and other adsorbents to remove various pigments, colloids, oxides, etc. in the oil.
(6) Deodorization of palm oil: Use the principle of vacuum air extraction to remove low-molecular odor substances, free fatty acids, monoglycerides, glycolipids, sulfides, thermal decomposition products of pigments, etc. in the oil.
(7) Dewaxing of palm oil: Freezing, crystallization or winterization crystallization are mainly used to fractionate the waxes and fats in the oil.
