Process comparison of the plant oil pressing extraction and solvent extraction

Preface:At present, some national standards for edible oils require clear information about the processing technology and the country of origin of the raw materials. This measure fully respects consumers’ right to know.  In order to better help ordinary consumers understand the processing technology of edible oil, let’s have a look.

Now, there are generally two ways to get edible vegetable oil: pressing and solvent extraction.

• What’s pressing and solvent extraction?
•  The advantages and disadvantages of the two processes
• Take their strengths from two processes
• From crude oil to product oil
• Pressing and solvent extraction, which one is better?

1. What’s pressing and solvent extraction?

Pressing: Adopts physical pressing way to extract oil from materials. It originated from the traditional oil making method of workshop, and the current pressing method is industrialized operation. Pressed oil is a product that is extruded from the oil containing oil by crushing, flaking rolling, cooking, and pressing. It belongs to a physical method of oil making.

Solvent extraction: It is a method adopted physical and chemical principles to extract oil fats from oilseeds by non edible solvents. The solvent extracted oil is a method of extracting oil from oil material by crushing, flaking rolling and cooking , using edible grade solvent (n-hexane) , which is a chemical extraction method.

No matter pressing or solvent extraction method ,it just produce crude oil. Usually crude oil are not edible. We need remove all kinds of impurities by some physical and chemical methods, such as gossypol, aflatoxin, solvent residue, etc. The cooking oil on the table can not be produced simply by pressing or solvent extraction, which requires complex physical and chemical processes.

2. The advantages and disadvantages of the two processes

The squeezing method is a pure physical pressing oil processing technology, which is produced through material selection, roasting, physical pressing, and finally through natural plant fiber filtration technology. This method does not add chemicals, can preserve the rich nutrition in the oil , contains no chemical solvent pollution and chemical antiseptic antioxidants, which can ensure the safety, purity, nutrition and delicacy of the product. It meets the health needs of the human body and is suitable to eat for a long time. However the oil rate is low. The “pressing oil process” is now widely used in domestic high grade oil products such as peanut oil, olive oil, nut oil, sesame oil and so on.

The residual oil in the oil residue can be reduced to less than 1% by the solvent extraction method. Taking soybean as an example, the oil yield of solvent extraction method is 50% higher than that of pressing method. Its greatest characteristics are high oil yield, low production cost and high economic returns. This is also one of the reasons why soy salad oil is generally lower than that of pressed oil.

3. Take their strengths from two processes
In modern oil processing plants, direct oil extraction is used for some low oil content oils, such as soybeans. For some materials with high oil content, such as rapeseed and peanuts, Adopt the process of solvent extraction after pressing is appreciated. The pure pressing process is just only reserved for pressed oil with special flavor.

For the current market hot food blended oil,Because it is full of rich nutrition of peanut oil, rapeseed oil, corn oil, sesame oil, soybean oil and other raw materials . Among them, peanut oil, sesame oil and corn oil are squeezed, and soybean oil is solvent extraction process.

For the above two kinds of oil making methods, the production enterprises will make their choose according to different needs, take its strengths and complement each other, and usually both of two methods are adopted at the same time by the same enterprise. For example, the oil extracted from the pressed oil cake will be used again. The single production process can not meet the production needs of the enterprise. Saving resources and pursuing efficiency are the foundation of enterprise development.

4. From crude oil to product oil

No matter whether it is squeezed or solvent extracted oil, it’s not edible. It is called “crude oil“. There are all kinds of impurities,in which some are extremely harmful(such as gossypol in cottonseed oil)

According to the materials, different manufacturing processes can be selected. Usually Such as sesame seeds, peanuts, olives, rapeseed and so on ,which has with high oil content. It’s suitable to choose pressing method to extract oil; however for some materials with low oil content,such as soybean and rice bran. It’s suitable to choose solvent extraction method. In addition, “water dissolution method” and ” water extraction process” are also applied.

Most of the solvent extracted oil is colorless and tasteless, the special nutrients of raw materials are retained , such as oryzanol in rice bran oil. Different edible oils need to meet different national standards. Therefore, not all oil have only one kind of color. According to the different grades of refining,raw materials and manufacturing processes here’s different color for every kind of oil.and color standard is different in national standard. Therefore the color of oil is not the only criterion for choosing vegetable oil.

5. Pressing and solvent extraction, which one is better?

The oil yield of pressing method is low, so the raw materials used for pressing oil must be with high oil content, and most of them are oil crops. Furthermore if noly adopt pressing method, residual oil rate is high in the oil cake, Therefore, in order to pursue efficiency and consider long-term development, modern enterprises will also solvent extract residual oil from pressed oil cake.

The solvent extraction method is suitable for most oil materials , especially those with high nutritional value but low oil production rate. Because of the superiority of the modern solvent extraction process, which has been widely used in the process of oil production. About 90% of the oil production in the world is made by solvent extraction method.

Therefore, the pressing method and the solvent extraction method are the same as the production process, each has the advantage and shortage, here’s no strict standard to judge which one is better. The production process is not the absolute standard of determining the quality of the plant oil. For individuals, first of all, it is clear that we need ensure cooking oil is safe,meeting with the national standard of cooking oil , then choose one kind of cooking oil which is more suitable for yourself.  To compare the nutrients in the oil, look at what nutrients you need to take at present. Because different oil has different nutrition. As for enterprises, it is good process,which is more helpful for the development of enterprises when the product oil reached the quality standard .