Several Methods Of Refining

After the initial press or leaching of the machine oil, we call it crude oil, and there are many impurities in the crude oil, these impurities will make the oil metamorphic, harmful to human health. The purpose of refining is to remove the solid impurities contained in the oil, free fatty acids, phospholipid, colloid, wax, pigment, odor and so on. So the oils in our daily life, whether squeezed or extracted, almost must be refined before consumption.

The crud oil is usually dark in color, poor in transparency or even cloudy. After long standing, there are sediment and suspension. Some crud oil has pungent odor and a lot of foam. After refining, cooking oil can store longer. So how to refine crude oil, we summed up the following three commonly used methods:

1.       mechanical method: mainly including precipitation, filtration, centrifugal separation and other steps, is to use centrifugal oil filter to separate the mechanical impurities in the grease and part of the gel soluble impurities.

2.       chemical method: mainly including acid refining, alkali refining, in addition, there are fat, oxidation and other steps, acid refining is treated with acid, mainly to remove pigment, colloidal impurities, alkali refining is treated with alkali, mainly to remove free fatty acids, oxidation is mainly used for decolorization.

3.       physical and chemical method: mainly including hydration, decolorization, steam distillation, etc., hydration is mainly to remove phospholipids, decolorization is mainly to remove pigment, steam distillation is used to remove odor substances and free fatty acids.

Although not all crude oils cannot be eaten directly, most crude oils are harmful to human health when consumed directly. For example, eating more crude cottonseed oil for a long time will make people suffer from sunburn.There will be systemic weakness, less sweating, skin burning, flushing, palpitation shortness of breath, dizziness, loss of appetite and other symptoms.Through refining, the water content, impurities, acid value and peroxide value of the oil can meet the quality standards set by the state. Oil is also more favorable for storage, not easy to rancidity and deterioration.Cooking with refined oil also does not produce a lot of smoke and maintains the flavor of the oil.