Extraction of bioactive compounds from yerba mate (<i>Ilex paraguariensis St.-Hil</i>.) leaves by packed-bed extractor using hot water as solvents: Kinetics study and mathematical modeling

Abstract

<abstract> <p>The aqueous packed-bed extraction of bioactive compounds from yerba mate leaves was evaluated given their potential application in the food industry. The influence of temperature (50–70 °C) and feed flow rate (10–20 cm³/min) was investigated by central composite design. A mathematical model derived from the differential equation of mass conservation in solid and liquid phases was used to describe the concentration of total phenolic concentration over time, considering a finite volume-based algorithm to solve this multiscale model along the column length and particle radius. The findings demonstrated that higher temperatures improved bioactive chemical extraction yields, although feed flow rate played a role at low temperatures because it improved external mass transfer. Caffeic acid, caffeine, and chlorogenic acid were the principal bioactive chemicals studied, with the highest concentrations extracted being 156.3 × 10⁻², 273.5 × 10⁻², and 351.6 × 10⁻² mg/g_YM (mg of bioactive per g of yerba mate), respectively, obtained after 60 minutes of extraction process at 70 °C and a flow rate of 10 cm³/min. The amount of these predominant bioactive compounds extracted exceeded 90% of the total content that could be obtained using water as a solvent. The mathematical model evaluated showed relative mean errors lower than 3% and R² higher than 98%, suggesting a good fit for the experimental data, with the external mass transfer and effective intraparticle diffusion coefficients ranging between 8.75 × 10⁻⁸ to 1.77 × 10⁻⁶ m/s and 9.34 × 10⁻¹¹ to 3.06 × 10⁻⁹ m²/s, respectively.</p> </abstract>