Yoghurt Fruit Preparations - Herbstreith & Fox

Gel Formation of Low Methylester Pectins
Low methylester pectins, like high methylester
pectins, also gel according to the ”sugar acid
gelling mechanism”. In addition to this, low
methylester pectins are also able to form
bonding zones with divalent cations, such as
calcium ions. The bonding is conducted by
complexation of the divalent ions (“egg-box“
gelling model). Gelation with calcium ions is
relatively independent of the soluble solids
content and the product pH.
Ca 2+ Ca 2+ Ca 2+ Ca 2+ Ca 2+ Ca 2+ Ca 2+ Ca 2+
HO
HO
O
O
O
HO O
O
HO O
HO O –
COO – HO O – COO –
O
O
O O
O
OH
OH
Ca 2+ Ca 2+
HO
HO
O
O
–
O
OOC
–
–
O O
O
OH OOC
–
O
OH
O OH
OH
O
O
O
O OH
O OH
Fig. 11: Gelling mechanism of low methylester pectins
Gel Formation of Low Methylester Amidated
Pectins
Low methylester amidated pectins, like low
methylester pectins, gel according to the
“sugar acid gelling mechanism“ as well as with
divalent cations. Due to the presence of the
amidated groups additional cross linkage is
created by way of hydrogen bonds. The more
amidated groups are present, the firmer the
respective gels.
The ratio between degree of esterification and
degree of amidation determines the so-called
calcium reactivity of low methylester amidated
pectins. Calcium reactivity measures the capa -
city to form a gel with a specified setting time
under defined conditions at a constant calcium
ion concentration.
21
Fig. 12: Gelling mechanism
of low methylester amidated
pectins
Pectins in Yoghurt Fruit Preparations