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The operating procedures of oil refining equipment usually include dewaxing, winterization and fractionation. Separation of fats and oils is a process of crystallizing and separating components with relatively high melting points based on the melting point difference between triglycerides and purifying them separately. The dewaxing and winterization of fats and oils belong to a special case in fractionation.

Edible oil dewaxing is the removal of high melting point wax fat from liquid oil. The wax fat in vegetable oil is contained in the seed coat, shell and germ of vegetable oil. Different vegetable oil and different processing methods have different wax fat content. Its solubility in grease is very low, and its melting point is relatively high (78-82 degrees), so it cannot be absorbed by the human body, and it is difficult to be transformed.

The content of wax in oil is very small except rice bran oil, which accounts for about 5%. Therefore, in daily production, the dewaxing of rice bran oil needs to be treated separately, and other vegetable oils are generally removed by winterization and dewaxing. As for winterization, it refers to the removal of high melting point triglycerides (mainly saturated esters) from liquid oils (such as cottonseed oil, etc.). The main purpose is to produce high-quality edible oil.

Edible oil fractionation is essentially divided into two parts: crystallization and solid-liquid separation.

The crystallization process of grease is generally divided into three stages:

(1) Make the grease or melt it quickly cool down to form a supersaturated state, so that the high melting point can fully begin to separate out;

(2) Slow cooling and slow stirring (135/min) promote the formation of crystal nuclei;

(3) Continue to cool down to the target temperature to increase the size of the crystal (also known as the crystal growth stage), and then wait for separation.

The main conditions for crystal formation:

(1) Crystallization temperature. The temperature is required to be lower than the freezing point of its solid fat.

(2) Stirring speed. Generally controlled at 10-13r/min.

(3) Cooling rate. Every kind of fat has its own specific freezing crystallization curve.

If you want to know more about the edible oil dewaxing fractionation process, please feel free to contact us!