The amount of LM-pectin required for the formation of such
gel decreases with the DE. The strengths of such ionic bonded gels
are strongly dependent on the DE. Monovalent ions such as
sodium, which can also react with free carboxyl groups, can affect
gel formation because they decrease the cross-linking reaction of
calcium and improve the solubility of LM-pectin in the presence of
calcium (Axelos, 1990). Although sugar is not essential for gel
formation with LM-pectins, the presence of small amounts (10-20%)
of sugar tends to decrease syneresis and adds desirable firmness of
these gels (Christensen, 1986). When some sugar is present, the
amount of calcium required to form gel is reduced. High
concentrations of sugar (60% or higher) interfere with gel formation
because the dehydration of the sugar favours hydrogen bonding and
decreases cross-linking by divalent ion forces.