Acerolaʹs pectin methylesterase: studies of heat inactivation

The effect of temperature on the activity of acerolaʹs pectin methylesterase (PME) was studied to determine its heat-inactivation. The acerolaʹs pectin methylesterase (PME; EC: 3.1.1.11) is very stable at 50°C (10% loss of activity in 100 min) and needed 110 min for its inactivation at 98°C. These values are much higher than the ones required for inactivation of the citrus PME, that has been reported as being equal to 1 min at 90°C. Heat-inactivation of PME was shown to be nonlinear, suggesting the presence of fractions of PME with differing heat-stabilities. The times to inactive the enzyme at 98, 102 and 106°C were 110, 10 and 2.17 min, respectively. The Z value (the rise in temperature necessary to observe a ten times faster heat-inactivation) was 4.71°C.