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.
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:
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