Characterization, bioactivity evaluation, thermo-kinetic studies of mango (Mangifera indica L.) peel extract, and its applicability in oxidative stabilization of biodiesel

Supercritical fluid extraction (SFE) of mango peel (MP) waste, characterization, kinetics, and thermodynamic studies was carried out in this work. Experimental conditions employed for the extraction process were a CO₂ flow rate of 9.8 g/min, a fixed pressure of 25 MPa, and different temperatures of 40–80 ℃ over varied extraction times of 30–150 min. High-performance liquid chromatography (HPLC) was used to isolate three (3) target bioactive compounds namely, quercetin, beta-carotene, and gallic acid, whose quantities were estimated as 1.2983, 3.6987, and 0.0254 mg/g respectively. The applicability of using Elovich’s, Hyperbolic, and Pseudo second-order models to study the extraction kinetics of MP liquid extracts derived from SFE was investigated and validated using calculated error functions. The result shows that the experimental data were best fitted by Hyperbolic, followed by Pseudo second-order and Elovich’s model respectively. Thermodynamics parameters gave positive values of entropy change (ΔS) = 0.144 Jmol⁻¹K⁻¹, enthalpy change (ΔH) = 59.78 KJ/mol, and a negative Gibbs’ free energy, (ΔG) = −8.88 KJ/mol, indicating an irreversible and endothermically spontaneous process respectively. Finally, the work also unveiled the potency of MP liquid extracts as a low-cost and sustainable source of antioxidants for improving biodiesel’s oxidative stability. Graphical Abstract: (Figure presented.)