Evaluation and optimization of supercritical extraction of insulin from Otostegia persica

In this study, the extraction of insulin from otostegia persica was enquire by Soxhlet extraction and modified supercritical CO2 with methanol as solvent and 30 min of static time. Design of experiment was executed with response surface methodology (RSM) using Mini Tab software 17. The operating temperature (40–60◦C), pressure (15–35 MPa),dynamic extraction time (60–120 min) and CO2 flow rate (0.8–2 ml/min) were regarded as the range of operating variables UV test was applied to recognize and quantitatively determine the amount of extracted insulin. Response surface analysis proved that R2 and modified R2 of the model were 98.16%and 96.54%, respectively. The RSM modeling prophesy the optimal operating conditions to be the pressure of 28.1 MPa, temperature of 47◦C, CO2 flow rate of 2 ml/min and dynamic extraction time of 109 min in which the maximum absorption coefficient of 0.