Procyanidin and proanthocyanidin extraction from Arachis hypogaea skins by using supercritical carbon dioxide: Optimization and modeling

The goal of this study is to recover high procyanidins and proanthocyanidins as promising compounds from Arachis hypogaea skin using supercritical carbon dioxide (ScCO₂). Solubility models determined the solubility of procyanidins and proanthocyanidins in ScCO₂ and ethanol as a modifier. The parameters of this study were pressure (10 to 30 MPa), temperature (313 to 343 K), and flow rate of ethanol (0.075 to 0.225 ml/min). Response surface methodology (RSM) revealed that the optimum conditions were at 20.39 MPa, 333.23 K, and 0.17 ml/min with 2,325.23- and 409.95-µg/g procyanidins and proanthocyanidins, respectively. In the modeling part, the Chrastil model gave the best correlation to the flavonoids' solubility with 3.01% of average absolute relative deviation (AARD). The application of RSM and modeling were successful in obtaining a high amount of procyanidins and proanthocyanidins. Practical applications: Peanut skin as agriculture by-products contains highly valuable compounds such as procyanidins and proanthocyanidins. However, toxic and conventional solvent has usually been used to recover procyanidins and proanthocyanidins. To overcome this drawback, supercritical carbon dioxide (ScCO₂) extraction is applied to extract the valuable compounds from peanut skin. Semiempirical model has been used in this study to determine the solubility behavior to enhance the solubility of procyanidin and proanthocyanidin contents. The results show that an endothermic reaction took place to improve the solubility.