2.5.2. Pectinase activity
Pectinase activity was determined by hydrolyzing 0.5% (w/v) citrus
pectin substrate (60% degree of esterification) (Sigma) in
50 mMsodium acetate buffer at pH 5. The reaction mixture contained
0.1 mL enzymatic solution and 0.9 mL substrate and was incubated
for 30 min at 30 °C. The reaction was finished by addition of 1.5 mL
of DNS. Released reducing groups were calculated from absorbance
measurements at 540 nm (Oliveira et al., 2006). One unit (U) of pectinase
was defined as the amount of enzyme that released one μmol of
reducing groups/min, under the given assay conditions.