Systematic investigation for extraction and separation of polyphenols in tea leaves by magnetic ionic liquids

BACKGROUND: Magnetic separation has become a mature industrial technique in many fields and its application in the food and agricultural fields is expected for further extension. Furthermore, there has been little application of magnetic ionic liquids in the preparation of bioactive products. In the present study, 0.8 mol L-1C3MIMFeCI4 in its aqueous solution was found to be ideal for the extraction of active constituents from tea leaves. After extraction, polyphenols, caffeine and ionic liquid were also satisfactorily separated from the crude extract by various easy operations. RESULTS: The average extraction efficiency of tea polyphenols could reach up to 185.38 g kg(-1) and the recovery percent of the magnetic ionic liquid was 99.8% through an external magnetic field. The extraction process was more consistent with a pseudo-second order kinetic model. Moreover, C3MIMFeCl4 had no effect on the stability of tea polyphenols, which was very different from ordinary ferric salt. The presence of magnetic ionic liquid had a positive effect on the antioxidant activity of the product. CONCLUSION: The developed method had a good performance for selective extraction together with separation of tea polyphenols and caffeine, which is expected in the preparation of more similar active components from food and agricultural resources as a useful multifunctional solvent. (C) 2018 Society of Chemical Industry