Abstract: The kinetics of extracting pectin from Premna microphylla Turcz. leaves with acid-solution was studied. A kinetic model of pectin extraction is proposed taking account of impact of dissolved pectin molecule degradation. The maximum yield and optimal extraction time were determined using mathematical methods. It can be applied to describe extraction of pectin from P. microphylla leaves using hydrochloric acid at temperatures of 60,70,80 and 90℃ in laboratory. The rate constant of extraction was established to be varied from 3.01×10^-4 s^-1 at 60℃ to 8.64×10^-4 s^-1 at 90℃,while the maximum yield of 8.007% was obtained at 90℃ over a period of 50.19min. The theoretical results predicted with kinetic model were in good agreement with experimental data from P.microphylla leaves. The proposed theoretical model describes adequately the pectin extraction process in an acid medium, and provides an opportunity to predict the yield of pectin, the quantity of gradated pectin substances and the optimum duration of extraction.

Key words: Premna microphylla Turcz. leaves, pectin, extraction, kinetic model