ABSTRACT
Pectins belong to a group of closely related polysaccharides or pectic substances, located in the middle lamella and primary cell walls of higher plants (dicotyledons). The general term protopectin is often used to designate the native, insoluble pectins in the cell walls that cannot be extracted by methods that are non-destructive or non-degradative. The dominant feature of pectins is a linear chain of α-(1,4)-linked D-galacturonic acid units in which varying proportions of the carboxyl groups are esterified with methanol to methyl esters. This group of pectic substances covers the following:
● different methyl esters (pectins with different degree of esterification — DE), their salts (pectinates)
● unesterified pectic acid, its salts (pectates) ● different neutral polysaccharides linked to the
polygalacturonan backbone such as arabinans, arabinogalactans, arabinoxylans, and galactans
Portions of these neutral polysaccharides are a part of the isolated, commercial pectins divided into HM pectins and LM pectins with correspondingly high and low methyl ester content. Amidated pectins are obtained by saponification of HM pectins with ammonia under alkaline conditions.
