2.3. Pectin methyl esterase activity
For enzyme extraction, twenty grams of fruit pulp were blended
in 60–100 mL 0.15 M NaCl,
filtered through two layers of cheesecloth,
and centrifuged at 672
g for 30 min at 4 C to remove debris
(Castaldo et al.,1989; Denes et al., 2000). The supernatant was used
as an enzyme source. The activity of PME was determined by
measuring the increase in acidity after hydrolysis of pectin by the
enzyme (Mahadevan and Sridhar, 1982). Pectin methyl esterase
activity was expressed as mass of PME hydrolyzed per mass of fruit
pulp, mg/kg (Balaban et al., 1991).