APPLICATION OF HERVAS AND PELEG KINETIC MODELS TO STUDY MICROWAVE-ASSISTED EXTRACTION OF ANTIOXIDANT SECONDARY METABOLITES FROM TRICHILIA ROKA ROOT BARK

Olga Nana*, Jean Momeni, Roli Karole Tsatsop Tsague, Nicolas Yanou Njitang, Martin Benoît Ngassoum

Application of the Hervas and Peleg kinetic model was investigated for predicting kinetics of extraction of polyphenols, flavonoids and limonoids from T.roka root bark through microwave assisted process under four independent variables (variable irradiation time X1, and fixed irradiation power X2, liquid-to-solid ratio X3 and methanol concentration X4). The maximum extraction efficiency was achieved with microwave irradiation power: 400 W, liquid- to-solid ratio: 1/20 mL/g and methanol concentration 95%. From Hervas model, the concentration of total limonoid (TL) and total polyphenol (TPP) release at equilibrium Co were respectively 425 and 542010 μgE/gDW with a diffusion coefficient k of 0.02 and 0.06 s-1. According to Peleg’s model, the maximum extraction quantities (a) of TF, TL and TPP from T. roka root bark (Co) are 500.00, 50.00, and 833333.33 μgE/gDW respectively and with the respective extraction velocity coefficients (k) of 0.014, 0.03; and 0.04 s-1. These parameters were obtained at the maximum irradiation time of 60 and 80 s respectively for limonoids and phenolic compounds with the extraction kinetic constants of 40 and 45 s-1. The Hervas model best adjust the extraction of TL and TPP, Peleg model best adjusts the extraction of the three secondary metabolites. The correlation analysis of the mathematical regression model indicated that a first and second-order polynomial model could be employed to obtain the highest recovery of secondary metabolites. The closeness of experimental values, with the predicted ones indicating the good similarity of the models used.