What is the refining process of cottonseed oil? What is the purpose?

Cottonseed oil is one of the most common edible oils in the world. We all know that crude cottonseed oil needs refining before it can be eaten. Then what is the refining process and what is the purpose of refining? Let’s have a look.

Cottonseed oil refining process:

Crude cottonseed oil → refining degumming → decolorization → filtration → deodorization → filtration → refined cottonseed oil

Cottonseed oil refining flow chart

1. Hydration and degumming

Using the hydrophilicity of colloidal impurities such as phospholipids, a certain amount of water or electrolyte dilute solution is added to the crude oil while stirring, so that the colloidal impurities in the crude oil can absorb water, swell, agglomerate and separate. In the process of hydration and degumming, phospholipid is the main substance that can coagulate and precipitate except protein, mucus and trace metal ions.

2. Alkali refining and acid removal

All unrefined crude oils contain a certain amount of free fatty acids. The process of removing free fatty acids from fats is called deacidification. Deacidification methods include alkali refining, distillation, solvent extraction and esterification. Alkaline refining and steam distillation (physical refining) are widely used in industrial production.

Cottonseed oil refining degumming photo

3. Adsorption decolorization

Oil adsorption decolorization is the use of some substances (such as bleached soil, active clay, activated carbon, etc.). It has strong selective adsorption for pigment, adsorbing impurities such as pigment in oil under certain conditions, so as to achieve the purpose of decolorization. The oil treated by adsorbent can not only improve the color of the oil, remove the colloid, but also effectively remove some trace metal ions and some substances that can cause poisoning of hydrogenation catalyst, thus providing a good condition for further refining (hydrogenation and deodorization) of the oil.

Cottonseed oil adsorption decolorization photo

4. High temperature deodorization

It is a process of removing abnormal odor substances by steam distillation under high temperature and high vacuum by taking advantage of the difference in volatilization of odor substances in fats and triglycerides. The principle of steam distillation deodorization (also known as stripping) is that water vapor through oil containing odor components, vapor liquid surface contact, water vapor is saturated with volatile odor components, according to its partial pressure ratio escape, so as to achieve the purpose of eliminating odor components.

Cottonseed oil high temperature deodorization photo

The purpose of refining cottonseed oil is because cottonseed oil contains gossypol, which is a toxic substance that can cause bleeding, nerve disorders, weight loss and affect fertility. Edible gossypol containing more wool oil can cause poisoning. Second, besides gossypol, the crude oil also contains colloidal impurities, free fatty acids, waxes and other impurities composed of phospholipids, proteins and trace elements. Harmful impurities need to be removed by refined refining equipment to ensure the edible safety and quality of cottonseed oil and prolong the storage time of oil.(Related reading:What is the purpose of edible oil refining?)

Cottonseed oil refining machine photo

Therefore, crude cottonseed oil is not edible. If you want to know more about cottonseed oil production equipment, you can feel free to contact us, we will give you the best service and professional advice.