Lipids are traditionally removed from seeds by mechanical crushing and solvent extraction. During the mechanical crushing process the oilseed is cleaned, cracked, flaked, and cooked before entering a mechanical screw press. Seventy-five percent of the oil of sunflower seeds can be extracted by crushing, and the fatty cake then contains about 15% of oil. The oil levels remaining in the cake can be reduced to less than 2% by solvent extraction. However, the crude oil has to be refined as it contains many impurities and approximately 600 ppm phosphorus. A new process, in which sunflower seeds are pressed in a twin-screw extruder, is examined here. The screw profile was first optimized. Oleic sunflower seeds were crushed and 80% of the oil was removed. The resultant oil was of good quality, with acid numbers below 2 mg KOH/g of oil and total phosphorus contents of about 100 ppm. The influence of pressing temperature and of fresh seed moisture content was determined. High pressing temperature and low moisture content improved oil extraction. The quality of the meal was examined through the solubilization of its proteins in alkaline water at 50°C. The fatty meal proteins remained quite soluble, and therefore one can assume that they were still relatively close to their native conformation. The pressing of oleaginous material in a twin-screw extruder provides a new option to traditional processes.
Our work is about the extraction of sunflower seed oil in a twin-screw extruder with or without the injection of 2-ethylhexanol and acidified 2-ethylhexanol. 2-Ethylhexanol is mixed with phosphoric acid. The oil recovery is increased to 90% by the co-injection of acidified alcohol. Mixing phosphoric acid with the alcohol enhances the lability of the oily spherosomes. Its addition increases the destruction of the membranes enveloping the lipid-containing organelles to release the oil more easily. Phosphoric acid exhibits an extracting and a degumming role. The best oil quality was obtained at a low extraction temperature (80°C), when 88% of the oil was removed. After alcoholic distillation, the oil exhibited a total acid value (mineral acidity plus organic acidity) of 4 mg KOH/g of oil and an organic phosphorus content below 30 ppm.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.