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Soybean Oil Refining Process

Soybean is the most widely cropped seed and Refined Soybean oil is the most eatable oil these days. Soybeans are cropped in many countries including East Asia, Europe and America.

Soybean Oil Refining Process Flow Diagram
Soybean Oil Refining Plant

Soybean have the 20% fat including the 3% saturated fats and 4% monounsaturated fats, polyunsaturated fats. Soybean is a rich source of the protein. The DOC (De oiled cake) obtained after solvent extraction is high protein meal and widely used for the animal food as one of the raw material.

The demand for the high protein cake is very high in the international market for making the animal food.

The soya protein is a very good substitute for the animal protein. This is very good for the vegetarian people since the soya protein consists the complete profile of protein.

This is to be noted that the soya protein can be cropped double in terms of the land area with respect to any other legume crop or pulse crop.

There is 18-19 % oil content in the soybean seed which is extracted through mechanical Screw Press or solvent extraction method by using the food grade commercial hexane. For extracting the oil from the seed, we need to moisture content. The seed is cleaned for the foreign particles and then cracked or dehulled.

The flakes are made in the flaker and the material is extruded also. The appropriate flake size needs to be maintained for the better extraction of oil from the raw material.

The solvent extracted oil is then refined in the edible oil refinery by following the steps of refining. The refining can be done either by physical route or by chemical route.

The soybean oil refining steps are:

  1. Degumming Section.
  2. Bleaching Section.
  3. Deodorization / De Acidification Section.

The refining by products received such as gums, spent earth, soap stock / FFA can be sold in the market and also can be done value additions. From soybean gums received from water degumming can be used for making the lecithin, which is widely used in the pharma and food industry.

Soybean Oil Refining Process Flow Diagram
Soybean Oil Refining Process Flow Diagram

Degumming / Neutralization Section of Soybean Oil Refining Process

The Crude Soybean Oil is obtained from Oil Mill Plant or from Solvent Extraction Plant. This crude soybean oil contains many undesirable impurities including gums which are mainly phosphatides. There are two type of Gums, called the Hydratable & Non Hydratable Gums. These Gums are removed in the Degumming Section of the Refinery. In this Degumming process we remove hydratable and non-hydratable gums to improve the physical stability of Soybean oil for next step in refining.

Goyum follows different type of degumming processes like Water Degumming / Acid Degumming / Enzymatic Degumming. The selection of the process does depend upon the methods of processing, chemicals used for the processing and the content of the phosphatides in the crude Soybean Oil or in any crude vegetable oil.

The Water degumming step in case of the Soybean Oil, is used for removal of hydratable gums. It is also used in degumming of crude soybean oil. These removed hydratable gums removed from the Soybean Oil are used as a Raw Material for making Lecithin, which is used in confectionary.

In the neutralization process the FzFA (Free Fatty Acids) are removed by neutralizing the FFA with slight excess of Sodium Hydroxide solution which is followed by the washing out of soaps & hydrated phospholipids. Some amount of Sodium Soap is generated during the process which can be used in the soap making industries or also can be Splitted in Fatty Acid form. The Soap generation in the neutralization process causes the loss of oil also due to which some people use the alternate process known as Physical Refining.

Now a day the people use to install the physical refinery for the large scale productions in order to minimize the operating cost since the physical refining is more economical then the chemical refining. In some cases, the chemical refining is also preferred instead of physical refining. The selection of the process type is done on the basis of the market needs.

Bleaching Section of Soybean Oil Refining Process

The bleaching of edible oils and fats is an important part of the refining process of crude oils and fats. We do bleaching of degummed and neutralized oil to remove several impurities mainly coloring pigments. These coloring pigments give the adverse effect to the physical appearance and quality of the oil.

The neutral oil after degumming / neutralization also does have some gummy matters and heavy metallic components in minor amount. These type of impurities have to be removed from the oil to achieve the high quality oil for the edible use.

In Bleaching of degummed and neutral oil we use natural or acid-activated clay minerals which adsorb coloring compounds on their surface.

Goyum’s unique design of the bleacher keeps bleaching earth in full suspension due to which there is no dead areas inside the bleacher which in turn gives lower utility consumption. Since the bleaching process is carried out under controlled parameters, the good quality oil is guaranteed in Goyum Bleacher.

Deodorization Section of Soybean Oil Refining Process

Deodorization of bleached and filtered soybean oil is done to remove the highly volatile compounds, mainly Free fatty acids, aldehydes and ketones which causes odor and smell in degummed and bleached soybean oil. Deodorization of oil is done under high vacuum and at high temperature (180 – 220°C). As we know that deodorization is a steam distillation process so it requires low pressure steam for proper circulation of oil in deodorizer. We keep the pressure of low pressure steam around 2-6 kg/cm².

There are some low volatile or high molecular weight fatty acids, heavy metallic compounds and aldehyde & ketonic group present inside the Soybean Oil which requires high temperature in order to remove them under controlled conditions which in turns removed in the Deodorization process. For the removal of the above mentioned fatty acids we need to raise the temperature of the oil inside the deodorizer up to the process temperature under high vacuum to achieve the FFA content of 0.05-0.1%.

There is some restriction in deodorization process of oil i.e. we can not raise the temperature inside Deodorizer more than 240 – 260 °C. If we go beyond this temperature profile under high vacuum, the polymerization of oil can take place.

Goyum Unique design of Deodorizer under high vacuum and less than 250 °C removes efficient amount of free fatty acid, aldehyde, ketone, coloring pigments and heavy metallic impurities.

As we know that refining of edible oil is basically divided in to two parts: – Physical refining and Chemical refining. In both process deodorization steps is require but the working principle of deodorizer for both the process is a little bit different.

After deodorization final Oil enters in to heat recovery tray and then oil is cooled in Heat Exchanger.

The Deodorized / Refined oil than passes through a polish filter and stored in storage tank.

If you are thinking about starting a vegetable oil production company, Goyum can help you with information about the soybean oil processing plant including oil pressing and refinery that are highly economical. If you have any questions on about how to start a soybean oil processing plant and refinery plant, contact us for more details, we are always ready to help you!