A comparison of methods to determine tannin acyl hydrolase activity

Six methods to determine the activity of tannase produced by Aspergillus ni ger Aa-20 on polyurethane foam by solid state fermentation, which included two titrimetric techniques, three spectrophotometric methods and one HPLC a ssay were rested and compared. All methods assayed enabled the measurement of extracellular tannase activity. However, only five were useful to evalua te intracellular tannase activity. Studies on the effect of pH on tannase e xtraction demonstrated that tannase activity was considerably under-estimat ed when its extraction was carried out at pH values below 5.5 and above 6.0 . Results showed that the HPLC technique and the modified Bajpai and Patil methods presented several advantages in comparison to the other methods tes ted.