Experimental and modeling for catechin and epicatechin recovery from peanut skin using subcritical ethanol

A study on the valorization of peanut (Arachis hypogea) skin as agricultural waste to recover bioactive compounds, including catechin and epicatechin, by subcritical ethanol extraction (SEE) is unexplored scientifically. Thus, this study aims to determine the parameter effects on peanut skin extract recovery by SEE, followed by identifying the semi-empirical modeling. The best conditions were 6 MPa, 4.53 ml/min, 86.23°C with responses of catechin 188.66 μg/g and epicatechin 336.41 μg/g. High pressure and temperature conditions are conducive to catechin recovery, whereas high pressure with low-temperature conditions is suitable for epicatechin enhancement. Del Valle Aguilera (DVA) fits the solubility of catechin and epicatechin in SEE effectively compared with the Chrastil model since it has the lowest average absolute relative deviation (AARD), which is 5.97% and 12.69%, respectively. As a result, this approach (SEE) may be used in place of the conventional method for extracting catechin and epicatechin for medicinal purposes. Practical Application: Subcritical ethanol extraction (SEE) is more uncomplicated and capable of attaining high extraction rates in a relatively short time to extract catechin and epicatechin from peanut skin. This is because subcritical ethanol rather than subcritical water extraction (SWE) is used to extract catechin and epicatechin from peanut skin at temperatures below 110°C. SEE also employs the lower pressure condition (P < 30 MPa) than SFE. Therefore, SEE is more advantageous than SWE owing to its lower operating conditions, allowing less energy usage. Hopefully, this technology (SEE) may replace the usual technique for extracting catechin and epicatechin for therapeutic uses.