Oil refining

Edible Oil Refining Process

Degumming

The process of removing peptidic impurities from crude oil using physical, chemical, or physicochemical methods is called degumming.

If the phospholipid content is high in edible oils and fats, they will easily foam, smoke, and smell when heated. Moreover, the phospholipids will oxidize at high temperatures, causing the oil to turn brown, and affecting the flavor of fried foods.

Degumming is based on the principle that phospholipids and some proteins are soluble in oil in the sewage state, but are insoluble in oil after forming hydrates with water.

Add hot water or water vapor to the crude oil, heat the oil, and stir at 50°C. Mix, then let stand and separate the water phase to remove phospholipids and part of the protein.

Deacidification

Free fatty acids affect the stability and flavor of oil. Free fatty acids can be removed by neutralizing with alkali, which is called deacidification, also known as alkali refining.

Decolorization

Crude oil contains pigments such as chlorophyll and carotenoids. Chlorophyll is a photosensitizer and affects the stability of oil. Other pigments affect the appearance of oil and can be removed with adsorbents.

Deodorization

There are some unwanted odor substances in oil, which are mainly derived from oil oxidation products. Use vacuum distillation and add citric acid to chelate excessive metal ions and inhibit oxidation.