Pectin in Foods

Abstract

Pectin, a complex polysaccharide, is a major component of non-lignified cell walls of dicotyledonous and some monocotyledonous plants. Its food-related functions are numerous and mirror many of its biological functions. As a naturally occurring component of raw or processed foods and as an additive in formulated foods it influences texture and rheological properties. Pectin's chemistry and functionality are dominated by galacturonic acid, which is organized largely as a linear homogalacturonan polymer. A variable proportion of the galacturonic acid residues may have a charge masking methyl ester on the C6 carboxylic acid. Thus, extensive variability can be found in both the total amount of charge as well as how the charge is distributed within the homogalacturonan region. The other major co-polymeric constituent has a repeating disaccharide of rhamnose and galacturonic acid and is believed to be dispersed between, and flanked by the homopolymeric galacturonic acid regions. Relatively short chain galactans, arabinans and arabinogalactans may be attached to the rhamnose residues. In situ pectin appears to exist as an interconnected network with cellulose and hemicellulose. Once extracted from plant tissue, pectin exists as a population of molecules in which no two are identical. This review addresses pectin structure, and how pectin structure is related to functionality, and how pectin structure can be engineered to impart predictable functionality.