One of my abstracts that was accepted for presentation at the Institute of Food Technologist’s Annual meeting was on low ester pectin. Pectin (link2) is a very intriguing molecule; a polysaccharide made mostly of galacturonic acid units. However, interspersed within the galacturonic acid polymer there are regions where rhamnose replaces the galacturonic acid and neutral sugars branch out of these regions. The galacturonic acid are frequently esterified with a methyl group. Alternatively, they can be amidated which means an amino group is attached. Amidation is typically added commercially to improve its functional behavior.
Pectin is used extensively in the food industry as a gelling agent. Not only is it used in jams and jellies, but also as a thickening agent and protein stabilizer. It is also added to diet sodas to improve mouthfeel.
Pectin is defined as low ester and high ester. In the US, the cut off between them is when 50% of the galacturonic acid groups are esterified. Low ester pectin requires minerals, typically calcium, to form gels.
Reference and source of picture:
Hoefler, A. C. (2003). Effect of calcium concentration, degree of amidation, soluble solids, and carbohydrate type on the gel strength of low ester citrus pectin. Animal and Food Sciences. Newark, DE, University of Delaware.