Solubilization and extraction of valuable compounds from peanut skin in subcritical water

Subcritical water extraction (SWE) is a process for extracting valuable compounds of catechin and epicatechin from the skin of the peanut (Arachis hypogea). The research's objective was to identify the best extraction conditions for recovering total catechin compounds (TCC), total epicatechin compounds (TEC), and total yield from peanut skin. The solubility of yield in subcritical water was determined using the Chrastil and Del Valle Aguilera models. The best conditions were 13.56 MPa, 11.66 ml/min, 160°C with responses of TCC 10.81 mg/g, TEC 8.41 mg/g, and yield 0.268 g/g. High pressure and temperature conditions were conducive to TEC recovery, whereas high flow rate conditions were suitable to TEC and total yield enhancement. The Chrastil model fits the solubility of yield in subcritical water effectively since it has the lower average absolute relative deviation, which is 85.507% compared to Del Valle Aguilera of 85.509%. The Chrastil and Del Valle Aguilera model was not suitable for the solubility of peanut skin extract due to high percentage of AARD. Practical applications: The catechin and epicatechin from 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. The best condition for obtaining maximum total catechin compounds (TCC), total epicatechin compounds (TEC) was determined using response surface methodology. Furthermore, in this work, a semi-empirical model was utilized to evaluate the effect of parameters to improve the solubility of bioactive compounds. TEC recovery was enhanced by high pressure and temperature, while TEC and total yield augmentation were enhanced by high flow rate.