Pectin

Pectin is a family of complex polysaccharides predominantly made of galacturonic acid and is a major component of plant cell walls, especially in the middle lamella. It is highly abundant in citrus peels and apple pomace, and commercially it is typically extracted from citrus fruits and apples. The extraction involves hot, acidic conditions that release pectic substances from the cell wall, followed by purification to yield commercially usable powders or granules.

Chemically, pectin comprises regions of homogalacturonan, a linear chain of α-1,4-linked galacturonic acid units, and other branched RG (rhamnogalacturonan) structures. A key feature is the esterification of carboxyl groups with methanol, described by the degree of esterification (DE). Pectin is commonly categorized as high-methoxyl (HM) with DE above about 50%, or low-methoxyl (LM) with DE below 50%. Some pectins are amidated as well, which can modify gelling behavior.

Gelling behavior is central to pectin's uses. HM pectin forms gels in the presence of high sugar concentrations and acidic conditions, making it well suited for traditional jams and jellies. LM pectin forms gels in the presence of multivalent cations such as calcium, enabling gelling with lower sugar content and the development of reduced-sugar products. Amended or modified pectins broaden these options further.

Applications include use as a gelling and thickening agent in foods (jams, jellies, dairy products, confectionery), stabilizers in beverages, and a source of soluble dietary fiber. It is also used in pharmaceuticals and cosmetics as a thickener or excipient. Pectin is regarded as safe for consumption and is valued for its functional and dietary properties.