PME activity was determined by measuring the amount of free
carboxyl groups produced as a result of action of PME on pectin.
Briefly, the juice sample was centrifuged at 10,000 g for 10 min at
4
O
C, and 10.0 mL supernatant was mixed with 40 mL pectin so-
lution (1 g/100 mL) containing 0.15 mol/L NaCl. The pH of the solution
was adjusted to 7.7 by the addition of 0.05 mol/L NaOH
solution and the time taken was recorded (50 ± 2
C). The PME
activity was calculated by employing the Equation (1), and the
amount of enzyme that released 1 mmol of carboxyl groups in
1 min is defined as one unit of PME (De Assis, Martins, & de Faria
Oliveira, 2007).