Pectin is a polysaccharide polymer compounds, by the D half-lactose aldose to a-1,4 sugar camp bond polymerization constitutes the main chain, sugar chain molecules, part of the completed group was methyl acetate, part of the shuttle group combined with a cation, part of the light group is ethyl phthalide, etc.. Pectin with the plant source, organization and development stage of the different, the number of residues in the side chain, the type and connection and other substituent presence of considerable changes, reflecting the pectin polysaccharides in the structure of the high degree of complexity.

In terms of chemical composition and biosynthesis, pectic polysaccharides are the most complex members of the plant cell wall polysaccharide family, with molecular weights generally ranging from 50-400 kDa. After a century of meticulous and in-depth research by many scientists, the structure and chemical composition of pectic polysaccharides have been gradually systematized and improved.

At present, the raw material of commercial pectin is mainly citrus peel (pectin content of 30%), lemon peel (pectin content of 25%) and apple peel (pectin content of coincidental%). In addition, sugar beet waste meal, sunflower disk, mango residue, onion in the pectin content is also relatively rich, can be used as raw materials for the production of pectin. Different sources of pectin, due to the molecular weight, the degree of methyl acetate, the number of differences in the number of groups, its physical and chemical properties, functional properties are not the same.