Supercritical carbon dioxide extraction of the residual oil from palm kernel cake

► Supercritical carbon dioxide used to extract residual oil from the palm kernel cake. ► Particle size reduction, pressure and temperature increment increased the oil yield. ► The highest removal of oil from palm kernel cake matrix was 9.26g oil/100g. ► The oil was obtained at pressure 41.4MPa, temperature 70°C and 150μm particle size. ► Defatted palm kernel cake can be used in many food industries such as food fiber. Palm kernel cake contains residual oil that has never been retrieved and it is treated as wastes. In this study, supercritical carbon dioxide was used to separate the oil from the palm kernel matrix. The studied extraction parameters were at the set pressures 27.57, 34.47 and 41.36MPa, temperatures 40–70°C and carbon dioxide flow rate between 1 and 3ml/min. The effect of the particle size on the oil yield was examined using different particle size that separated by sieving from ⩽106, ⩽150, ⩽180, ⩽250 and ⩽450μm. The results showed that the highest oil removed was 9.26g oil/100g sample (p