1. Structure
 |
| Galacturonic
Acid Unit |
|
|
Pectin for use
in food is defined as a polymer containing galacturonic acid units
(at least 65%). The acid groups may either be free, combined as a
methyl ester, or as sodium, potassium, calcium or ammonium salts,
and in some pectins amide groups may also be present.
Pectin
in the plant starting material is part of a very complex structure,
which gives shape to the soft non-woody parts of the plant.
Plant cell wall structure
diagram
Pectin in this state contains a range of neutral sugar molecules,
in a complex non-random structure, containing blocks of homogalacturonic
acid (sometimes called "smooth regions"), and blocks containing
many neutral sugar molecules (rhamnose, galactose, arabinose, and
lesser amounts of other sugars) in a highly branched structure (sometimes
referred to as "hairy regions").
Plant
Wall Cell Structure
When pectin is
extracted, much of the hairy regions are destroyed, leaving mainly
the smooth galacturonic acid regions, with a few neutral sugar units
attached or in the main linear chain. The nature and placing of these
neutral sugars may vary with the source material, and have some influence
on the properties of pectins from different origins. However, the
biggest influence on pectin properties is the degree of esterification
(DE), which determines, for example, the degree of reactivity with
calcium and other cations.
1. Structure
2. Types of Pectin 3.
Discovery & History 4.
Commercial Production
