What is Pectin?
1. Structure    2. Types of Pectin    3. Discovery & History    4. Commercial Production

2. Types of Pectin

Pectin as extracted normally has more than 50% of the acid units esterified, and is classified as "high methyl ester (HM) pectin".

HM pectin formula

The percentage of ester groups is called degree of esterification. High methyl ester pectins are classified in groups according to their gelling temperature as rapid set to slow set pectins (see application of pectins).

Modification of the extraction process, or continued acid treatment, will yield a "low methyl ester LM) pectin" with less than 50% methyl ester groups.

LM pectin formula

Some pectins are treated during manufacture with ammonia to produce amidated pectins, which have particular advantages in some applications.

Amidated pectin formula

Within each of these main types, there are many detailed variations prepared for different uses.

The structure of pectin molecules is the key to the properties of pectins, and their use in different applications.

Pectin molecules are long, and easily entangle with each other, causing thickening.		Pectin can improve the texture of low sugar drinks.
If enough sugar is added to reduce the availability of water to dissolve pectin molecules fully, the molecules stick together in smooth regions with ester groups to form a gel network.		Conventional high sugar jams depend on pectin to set, and also require a minimum sugar content.
Because the acid groups are relatively weak, changes in the acidity (pH) alter the amount of charge on the pectin chains. Pectins which can link together under acid conditions have enough charge at lower acidity (higher pH) to repel each other.		This explains why it needs both sugar and acid to set a jam or jelly.
The acid groups in pectins can react with calcium ions which have two positive charges, and can link two acid anion groups with negative charges. If enough negative groups occur together, as in low ester pectins, these can link pectin molecules together in a gel network without needing so much sugar.		Low ester pectins are used to make low sugar jams, and many different fruit preparations for use in the food industry.
Pectin molecules with a negative charge can bind to proteins carrying a positive charge and prevent them coagulating when heated.		Pectins can stop the milk protein in yoghurt from curdling with heat, so heat treated (UHT) long life yoghurt drinks can be made.

1. Structure    2. Types of Pectin    3. Discovery & History    4. Commercial Production