Optimization and modelling in flavonoid and phenolic compounds recovery from peanut skin by subcritical water

Subcritical water extraction (SWE) is a process for extracting phenolic and flavonoid compounds from the skin of the peanut (Arachishypogea). The phenolic and flavonoid compounds of peanut skin were frequently recovered using a hazardous solvent in a traditional extraction procedure. Subcritical water extraction is one of the methods for overcoming the toxicity of solvents. Therefore, the study’s aim was to identify the best extraction conditions for recovering total phenolic compounds (TPC), total flavonoid compounds (TFC), and antioxidant activity from peanut skin. The solubility of TPC and TFC in subcritical water was determined using the Chrastil and Del Valle-Aguilera models. The best conditions were 10.46 MPa pressure, 12.56 mL/min water flowrate, 120 °C temperature, 375.08 mg/100 g TPC, 396.24 mg/100 g TFC, and 87.96% antioxidant activity. The Chrastil model fits the solubility of TPC and TFC in subcritical water effectively since it has the lowest average absolute relative deviation (AARD), which is 2.81% and 4.47%, respectively. The findings demonstrate that a low temperature condition is ideal for increasing TPC and TFC.