Pectin Research Paper

2.1 Pectin

2.1.1 Biochemistry

The word ‘pectin’ comes from the Greek word pektos which means firm and hard, reflecting the ability of pectin to form gels. Pectin is a high molecular weight carbohydrate polymer which is present in virtually all plants. It is a structural component of the plant cells. The term pectin covers a group of polymers which vary according to their molecular weight, chemical configuration, and content of neutral sugars. Different plant types produce pectin with different functional properties.

Pectin consists of a chain of galacturonic acid (GalA) units which are linked by α-1,4 glycosidic linkages. It is negatively charged. The galacturonic acid chain is partly esterified as methyl esters. Pectin molecules can have a

However, pectin describes a family of oligosaccharides and polysaccharides that have common features, but are extremely diverse in their fine structures. However, all pectins are rich in galacturonic acid (GalA), and the FAO and EU stipulate that ‘pectin’ must consist of at least 65% GalA [2]. Three major pectic polysaccharides have been recognised along with many other minor components. Pectins are a family of covalently linked galacturonic acid-rich plant cell wall polysaccharides where all the polysaccharides contain galacturonic acid linked at the O-1 and the O-4 position to a more or less

HG is partially methylesterified at the C-6 carboxyl, may be O-acetylated at O-2 or O-3, and may contain other potentially crosslinking esters of uncertain structure. It is the simplest of all polysaccharides.

 Rhamnogalacturonan II (RG-II)

The most structurally complex pectin, RG-II, makes up 10% of pectin. Its structure consists of an HG backbone of at least 8 (and most probably more) 1,4-linked α-D-GalA residues with side branches (a–d) consisting of 12 different types of sugars in over 20 different linkages. RG-II usually exists in plant walls as RG-II dimers which form a macromolecular pectin