The structure of pectin is very difficult to determine because pectin
can change during isolation from plants, storage, and processing of
plant material (Novosel’skaya et al., 2000). In addition, impurities
can accompany the main components. At present, pectin is thought
to consist mainly of D-galacturonic acid (GalA) units (Mukhiddinov
et al., 2000), joined in chains by means of á-(1-4) glycosidic
linkage. These uronic acids have carboxyl groups, some of which
are naturally present as methyl esters and others which are
commercially treated with ammonia to produce carboxamide groups
(Fig. 1).
Fig.