The gel structure is a net-like formation of cross-linked pectin
molecules. The cross-linkages formed by ionic bonds between the
carboxyls are strong and produce a rather brittle, less elastic than
those formed by hydrogen bonding as in regular pectin. With
pectins of lower DE, there is an increasing probability for the
formation of cross-links with a given amount of calcium. As the
number of reactive carboxyl groups that can form a salt bridge
increases, the greater the chances are that the bridge will be formed.
Furthermore, because of the larger amount of charged groups,
de-esterified molecules are straighter than the esterified ones, so
they will be more likely to form calcium linkages (Thibault &
Rinaudo, 1985).