Modeling and Optimization of Phenolic Extraction from Arachis hypogaea L.’s Skin Using Response Surface Approach

Abstract

Peanut skin, a polyphenol-rich agro-residue, constitutes a promising renewable source of natural antioxidants for food and pharmaceutical applications. In this study, response surface methodology (RSM) based on a Box–Behnken design was employed to optimize the extraction of total polyphenol content (TPC) as a function of temperature, ethanol concentration, solvent-to-solid ratio, and extraction time. The TPC was determined by the Folin–Ciocalteu method, and the developed quadratic model was statistically significant (F = 40.74, R² = 0.98), indicating an adequate fit. Ethanol concentration and extraction time exerted the most pronounced effects, with significant quadratic and interaction terms. The optimal extraction conditions ( approximately 55 °C, 30% ethanol, 160 min) yielded extracts with high phenolic recovery and moderate antioxidant capacity (IC₅₀ ranged from 120 to 150 µg/mL, DPPH assay). The results validated RSM model is a reliable tool for optimizing polyphenol recovery from peanut skin. Additionally, it also highlights the potential of peanut skin valorization as a sustainable and cost-effective strategy for producing natural antioxidants, contributing to the circular bioeconomy and industrial exploitation of agricultural residues.