Fig. 3

pH-stability profiles of different enzymes from surface cultures of A. niger APS at pH 4.0 (a–c) and at pH 5.0 (d–f). The samples were withdrawn at 0, 2, 4, 6, 24 h and the residual activities were determined at 50 °C and expressed in terms of % of control. Enzymes in the cocktail were found to be highly pH stable under acidic conditions (pH 4–5)