Response surface optimization of supercritical CO2 extraction of α-tocopherol from gel and skin of Aloe vera and almond leaves

Supercritical fluid extraction (SFE) was studied as an alternative technology in the pharmaceutical industry for the separation of α-tocopherol from gel and skin of Aloe vera and almond leaves. The influence of operating conditions was investigated on the recovery of supercritical carbon dioxide (SC-CO₂) extraction of α-tocopherol from three-year old Aloe vera (Aloe barbadensis Miller) leaf gel. The obtained results were compared with the conventional Soxhlet extraction. Response surface methodology (RSM) was applied to optimize effective variables on the extracted recovery of α-tocopherol. The maximum α-tocopherol recovery of 53.41% from Aloe vera gel was obtained with employing RSM predicted optimal operating conditions of 32 MPa, 45.91 °C, 0.84 ml SC-CO₂/min and 140 min for extraction. The α-tocopherol extraction yield for gel and skin of Aloe vera and almond leaves at these optimal operating conditions were obtained 1.53, 16.29 and 2.61 mg/100 g dry sample, respectively.