Rapid purification of catechins using soybean protein

Abstract

For the rapid purification of catechins from tea leaves, soybean protein was applied. Amongst catechins [(-)-epigallocatechin (EGC), (+)-catechin (C), (-)-epicatechin (EC), (-)-epigallocatechin 3-O-gallate (EGCG), (-)-epicatechin 3-O-gallate (ECG)] in a tea leaf extract, the catechin gallates (EGCG and ECG) were specifically extracted by complex formation with soybean protein. The procedure is as follows : 1) Soybean protein was prepared from autoclaved de-fatted soybean. 2) The protein extract was mixed with a water extract of tea leaf and the pH of the mixture was adjusted to 4.5. 3) Catechin-protein complex, precipitated in the mixture, was filtrated and dried. 4) Catechins were extracted with acetone-water (1 : 1) from the catechin-protein complex. The complex of the catechin and soybean-protein would be a new food and/or pharmaceutical product, which is attractive by its bio-activities originated from both catechins and soy protein.