Distinction Between Crude Oil And Refined Oil

After initial press oil material, the product without filtration and refinement is called crude oil. And the oil after filtration and refinement, that is refined oil.

Crude oil is a unrefined oil or soaked vegetable oil. There are four types impurities included in crude oil:

1. Suspended impurity: like sediment, billet, powder and other solid impurities. The oil with these impurities is conductive to microbial activities, so it’s not edible.

2. Colloidal impurity: like fat, protein,sugar etc. During frying the colloidal impurity become dark precipitation and foam, of course which negative affects the color and flavor of the food, and the precipitation destroys the nutrition if oil.

3. Oil-soluble impurity: like free fatty acids, pigments, hydrocarbon waxes, aldehydes, ketones, etc., as well as trace metals, mercury, pahs, aflatoxin, which pollutes environment and is harmful to body.  

4. Water: crude oil contain a lot of water, water leads to oil go bad.

Refined oil produce from crude oil, which is filtered out harmful impurities. Refined oil meet the national quality standard.

There are three ways to refine crude oil:

1. Mechanical method: this method include precipitation, filtration and centrifugal separation, which is used to separate some colloidal impurities.

2. Chemical methods: this method including acid refining, alkali refining and lipid and oxidation. Acid refining can remove pigment and colloidal impurities.

Physical and chemical methods: including hydration, decolorization, steam distillation. Hydration mainly remove fat, decolorization mainly remove pigment, steam distillation used to remove odor substances and free fatty acids.