Pectin gelation characteristics can be divided into two main types: high methoxy gelation and low methoxy gelation.
Gelation of high methoxy pectin usually takes plave at a pH of below 3.5 and a total solids content of above 55%. This is the typical gel formed during jam making. high methoxy pectins are characterised by their setting time and the gel strength. Setting time is usually categorised as rapid set, medium set and slow set. High methoxy pectins gel slower as more of the methoxy groups are removed during processing. The gel strength is measured SAG units and the pectin garde is often expressed as the number of units of sugar that a unit of pectin can gel.
Low methoxy pectin is gelled with calcium ions and hence is not dependant on the presence of acid or a high solids content. The less ester groups present the more sensitive the pectin becomes to pectin and hence a rapid set, low methoxy pectin has the lowest level of esterification. Amidation can interfere with the gelation causing the gelation to be delayed. Another useful property of amidated pectins is the ability of the gel to reheal after shearing.
|Type||Methylation level||Amidation level||Common Description|
|High Methoxy||74-77||0||Ultra Rapid set|
|High Methoxy||71-74||0||Rapid set|
|High Methoxy||66-69||0||Medium Rapid set|
|High Methoxy||58-65||0||Slow set|
|Low Methoxy||40||0||Slow set|
|Low Methoxy||30||0||Rapid set|
Additional information on pectin structure and sources can be accessed using the arrows in the Further Reading box below.