Oil extraction of oleic sunflower seeds by twin screw extruder: influence of screw configuration and operating conditions

Generally, the position and spacing between two screw elements affected oil extraction yield. An increase of oil extraction yield was observed when the reversed screw elements were configured with increased spacing between elements or/and with smaller pitch screw. In addition, more oil extraction yield was produced as the temperature pressing, screw rotation speed and seed input flow rate were decreased. The higher oil extraction yield was obtained under operating conditions 80 °C, 60 rpm and 24 kg/h. Furthermore, the operating parameters influenced energy input and mean residence time of matter. Both energy input and mean residence time increased when the temperature pressing increased. However, increase of screw rotation speed and seed input flow rate decreased mean residence time. Effect of the operating parameters on oil quality was unimportant. In all experiments tested, the oil quality was very good. The acid value was below 2 mg KOH/g of oil and total phosphorus content was very poor, below 40 mg/kg.