Pectin is a heterosaccharide derived from the cell wall of plants. Pectins vary in their chain lengths, complexity and the order of each of the monosaccharide units. The characteristic structure of pectin is a linear chain of alpha(1-4)linked D-galacturonic acid that forms the pectin-backbone, a homogalacturonan. [HMDB] Pectin is a structural heteropolysaccharide contained in the primary cell walls of terrestrial plants. It is produced commercially as a white to light brown powder, mainly extracted from citrus fruits, and is used in food as a gelling agent particularly in jams and jellies. It is also used in fillings, medicines, sweets, as a stabilizer in fruit juices and milk drinks and as a source of dietary fiber. [Wikipedia]