Aqueous Two-Phase Extraction of Polyphenols Using a Microchannel System – Process Optimization and Intensification

Anita Šalić¹, Ana Tušek², Diana Fabek¹, Ivana Rukavina¹ and Bruno Zelić¹*

¹University of Zagreb, Faculty of Chemical Engineering and Technology, Marulićev trg 19, HR-10000 Zagreb, Croatia
²University of Zagreb, Faculty of Food Technology and Biotechnology, Pierottijeva 6, HR-10000 Zagreb, Croatia

Article history:
Received August 11, 2010
Accepted February 22, 2011

Key words:
polyphenols, gallic acid, aqueous two-phase systems, multifactor plan of experiments, evolutionary operation (EVOP), microextractor

Summary:
Polyphenols are one of the most numerous and widespread groups of compounds in the plant world. Nowadays, organic solvents such as methanol, ethanol, acetone, dimethylformamide, ethyl acetate and diethylether are mainly used for the extraction of polyphenols. These solvents require special process conditions and special care in the disposal of the used solvents. In this paper, the extraction of polyphenols from the model solution was performed using the aqueous two-phase system which contains 80–90 % water and represents low burden on the environment. The aqueous solution of gallic acid (GA) was used as a model solution of polyphenols. The extraction was performed in the aqueous two-phase system containing PEG₆₀₀₀/H₂O/(NH₄)₂SO₄ in a macroextractor (V=10 mL) and microextractor (V=14 μL). The influence of the process parameters, the concentration of gallic acid, pH and composition of the aqueous two-phase system was investigated in order to maximize the partition coefficient. The method of multifactor experimental planning was used to optimize the extraction process and the results were statistically analysed using the evolutionary operation method (EVOP). Optimal operating conditions of the extraction process were pH=6.50, γ_GA=4.50 g/L, the mass fraction of polyethylene glycol (PEG) ω_PEG=0.1037 g/g and the mass fraction of ammonium sulphate (AMS) ω_AMS=0.0925 g/g. Under these conditions the maximal partition coefficient of K=5.54 and the extraction efficiency of E=89.11 % were achieved and successfully applied for total phenol extraction from white wine in the macro- and microextractor. Approximately the same partition coefficients and extraction efficiency were achieved in the microextractor within a 60-fold shorterresidence time.

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