OPTIMIZATION, KINETICS AND THERMODYNAMICS OF THE SOLID-LIQUID EXTRACTION PROCESS OF FLAVONOIDS FROM ROSEMARY (ROSEMARINUS OFFICINALIS) LEAVES

Abstract

Solid-liquid extraction of total flavonoids (TF) from rosemary (Rosemarinus officinalis) leaves was studied in the present work. The effects of type of solvent and its concentration, temperature and extraction time on amount of flavonoids as well as the effects of these parameters on the kinetics and thermodynamic parameters of extraction process were investigated. The effects of the process factors on the TF were assessed using the full factorial test plan 2³. Extraction using 50% ethanol in a 50 ^oC during 100 min, was the most suitable conditions to produce a extract with high content of flavonoids (32.428 mg catechin equivalents / g rosemary leaves). The following two-parametric models were analyzed: non-stationary diffusion model trough the plant material, model of Ponomarev and parabolic diffusion model. All models gave a good fit to the experimental data (root mean square, RMS<2%, coefficient of determination, R²>93%). The ΔG^o, ΔS^o and ΔH^o values of the flavonoids extraction process were
-4.89 – (-7.02) kJ/mol, 23.59 – 25.91 KJ/mol and 0.95 – 9.90 kJ/mol, respectively, indicating spontaneous, irreversible, and endothermic process.