A twin‐screw extruder for oil extraction: I. Direct expression of oleic sunflower seeds

Abstract

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.

From crops to products for crops: preserving the ecosystem through the use of bio-based molecules

“…Finally, for the vegetable oils, the acid value (AV) is used to quantify free-fatty acid content (AFNOR, 2009), and the iodine value (IV) indicates the degree of unsaturation (AFNOR 2013). For a typical high-oleic sunflower oil, the acid value is below 2 mg KOH/g oil and the iodine value is between 80 and 90 g of iodine per 100 g of oil (Dufaure et al, 1999).…”

The thermo-mechano-chemical twin-screw reactor, a new perspective for the biorefinery of sunflower whole plant: aqueous extraction of oil and other biopolymers, and production of biodegradable fiberboards from cake

“…Conducted for nearly twenty-five years at LCA laboratory, several studies have highlighted the multiple possibilities of the twin-screw technology for both fractionation and valorization of agricultural resources. Some examples are following: (i) the mechanical pressing and/or the solvent extraction of vegetable oil from sunflower (Dufaure et al, 1999a(Dufaure et al, , 1999bAmalia Kartika et al, 2005, 2006, 2010Evon et al, 2007Evon et al, , 2009Evon et al, , 2010aEvon et al, , 2012a, neem (Faye, 2010), jatropha and coriander (Sriti et al, 2012;Uitterhaegen et al, 2015) oleaginous seeds, (ii) the extraction of hemicelluloses from lignocellulosic plant materials (Manolas, 1993;N'Diaye, 1996;Prat, 1998;N'Diaye and Rigal, 2000;Maréchal, 2001), (iii) the extraction of pectic substances from the pith of sunflower stalk (Maréchal and Rigal, 1999) or sugar beet pulp (Jorda, 2003), (iv) the extraction of vegetable proteins (Silvestre et al, 1999; Fig. 1.…”

Comparison of oil press for jatropha oil - a review

“…5) which successfully extracts oil from seed crops is a twin-screw extruder (Dufaure et al 1999;Prat et al 2002). The twin-screw extruder has two screws rotating in a cylinder with two parallel screw shafts that either rotate in the same direction (co-rotate) or rotate in opposite directions (counter-rotate).…”