Press cakes of sunflower and pumpkin seeds have been subjected to the extraction of residual oil using ethanol and hexane as solvents . The authors have observed a relatively great amount of residual oil in the solids obtained from extraction with ethanol and a great extraction of pigments with the use of the renewable solvent.
How does hexane extraction work?
As the solvent (usually hexane) passes down through the bed of oil-bearing material, the oil is dissolved in the solvent and carried away. When properly carried out with stages of extraction (as will be described), the extraction process results in a very good separation of the edible oil from the solids or nutritious meal fraction.
What is a good residual oil content for a hexane extractor?
A minimal residual oil content in the meal coming out of the hexane extractor is a clear benefit for a crushing plant; the more oil yield the better revenue for the crusher. In a modern and efficient extraction plant, a residual oil content ¡Ü0.5% for soybean meal is expected.
What is the difference between solvent extraction and hexane extraction?
In comparison, solvent extraction with hexane (the primary solvent used worldwide) will remove all but about ½% of residual oil, uses less horse power, and requires less maintenance. It is relatively efficient and reliable, and this is one reason why solvent extraction is the primary means of separating large tonnages of oil from protein meal.
