Real-time extraction control in soybean oil production

Soybean seeds are used to produce vegetable oil that can be used as such or as an ingredient in a variety of processed foods. Soybean oil is also used as a feedstock for biodiesel production.  

Measurement of extracted oil in hexane for extraction process optimization  

The oil from soybeans is extracted using commercial  hexane  in  solvent extraction. Up to 90% of the solvent remaining in the extracted oil evaporates and is then collected for reuse. The rest is separated with a stripping column. In the bottom of the column there is crude oil which is refined and blended for different applications.  
 
Next, the crude oil is refined by removing phospholipids and free fatty acids from its content. This is done in two stages. The first stage is degumming. The second stage of the refining  is  neutralization  or caustic refining. The free fatty acids are removed from the crude oil using an alkali solution. As a result, soap is produced which will be removed from the process with water. The alkali solution neutralizes any acid remaining from the degumming stage, and reacts  with  the  triglycerides  in  the  oil,  so  the  neutralization parameters  (type  of  alkali,  solution  strength,  temperature,  agitation  and  time)  must  be  optimized  to  minimize  the  yield  loss. As a result of the caustic refining, soapstock which is a mixture of soap, water and oil is produced as a by-product.  

Download the application note to learn how Vaisala Polaris Sanitary Refractometer helps to optimize the soybean oil extraction process by: 

• continuously measuring the amount of extracted oil in hexane. Typically, the concentration of the mixture after extraction is 30% oil and 70% hexane 
• monitoring the  refractive  index  value  of  the  oil  after  solvent has been removed and recovered in the separation column. This is done for quality control purposes
• monitoring the concentration of caustic soda to ensure efficient neutralization process. 

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