Degree of esterification
The polygalacturonic acid chain is partly esterified with methyl
groups and the free acid groups may be partly or fully neutralised
with sodium, potassium or ammonium ions. The ratio of esterified
GalA groups to total GalA groups is termed as the DE. Pectin might
be formed initially in a highly esterified form, undergoing some
deesterification after they have been inserted into the cell wall or
middle lamella. There can be a wide range of DEs dependent on
species, tissue, and maturity.