Pectin

From Encyclopedia Jr, free information reference for Kids

Pectin is a heterosaccharide derived from the cell wall of plants. Pectins vary in their chain lengths, complexity and the order of each of the monosaccharide units. It was first isolated and described in 1825 by Henri Braconnot.

Under acidic conditions, pectin forms a gel, and it can be used as an edible thickening agent in processed foods. This effect is used for making jams and jellies.

[edit] Biosynthesis

They are synthesised in the plant's Golgi apparatus and form a matrix in which the hemicellulose polysaccharides of the plant cell are embedded. An important part of fruit walls, pectin is broken down by the enzyme pectinase to pectinic acid and finally pectic acid. During this chemical breakdown process, the fruit gets softer as the cell walls degenerate.

[edit] Chemistry

Pectin is composed of three main polysaccharide types:

1. Homogalacturonan, which is composed of repeated D-galacturonic acid monosaccharide subunits, that are methyl-esterified to a varying degree.
2. Rhamnogalacturonan I, which is composed of alternating L-rhamnose and D-galacturonic acid subunits that contain α-(1-5)-L-arabinan and β-(1-4)-D-galactan side chains.
3. Rhamnogalacturonan II, which is a complex, highly branched polysaccharide.

The gelling characteristics of different pectins are influenced greatly by the degree of esterification of the molecule. Pectin releases small amounts of methane in a non-enzymatic reaction and methanol in an enzymatic reaction.

[edit] Medical uses

Pectin is used as an oral demulcent to alleviate symptoms of sore throat and mouth in some throat lozenges. Among these are Luden’s Throat Drops brand, Halls Fruit Breezers, and Dimetapp Get Better Bear sore throat pops.

If a sore throat persists for more than two days of taking a pectin product, or is followed by fever, headache, rash, nausea, or vomiting, see a doctor for a stronger treatment.

Pectin products can be taken as needed until throat discomfort subsides or disappears.

Be cautious when allowing young children to chew pectin products, as choking can occur.

[edit] Sources

Apples, plums, gooseberries and oranges contain much pectin, while soft fruits like cherries and strawberries contain little pectin. For commercial use, pectin is extracted from shredded fruit peel or pulp by adding hot acid. The pectin dissolves into the hot acid, and may then be precipitated as a gel by adding ethanol, methanol or propanol.

[edit] References

Braconnot, Henri. Keppler, Frank et al. Methane emissions from terrestrial plants under aerobic conditions. Nature 439, 187-190

[edit] External links

International Pectin Producers Association http://www.ippa.info

• Link page to external chemical sources.