Purification of Tannase of Aspergillus niger and its Effect on the Creaming of Tea Infusion

Abstract

Crude tannase preparation which was obtained by ammonium sulfate-precipitation from the mycelial extract of Aspergillus niger AKU 3303 was further purified by a procedure involving acetone precipitation, DEAE-Sephadex column chromatography, Sephadex G-200 gel filtration and SPSephadex column chromatography. The final enzyme preparation showed single band upon a disk electrophoresis.
The properties of the purified tannase were studied with reference to pH-activity relationship, temperature-activity relationship, pH-stability, heat-inactivation and effects of metal ions and other reagents.
It was found that activity of the crude tannase preparation to prevent creaming of tea infusion was slightly higher than that of the purified tannase when infusion was incubated with same units of each enzyme preparation.
Therefore, it was considered that the crude tannase preparation contains certain effective substances on the creaming of tea infusion, but their effects were very small comparing with that of tannase.