2.4. Analytical methods
Total pectinase activity (TPA) was determined by measuring the
reduction of viscosity of citric pectin solution (CP KELCO S.A, Brazil)
(6.3 g/L), in an acetate buffer solution 0.05 mol/L, pH 4.0. The
analysis was performed using 3.2 mL sample diluted in 14.8 mL of
citric pectin, at 30 C for 30 min. Thereafter, viscosity variations
were measured with a viscometer (BROOKFIELD ENGINEERING,
model DV-IIþ, USA). One unit of TPA was defined as the amount of
enzyme that reduces the viscosity to 50%, according to standard
conditions (Couri & Farias, 1995).