Pectin was first isolated in 1825 but his functionality has been always unknowingly beneficial ever since the first fruit preserves were made.
Pectins are a high molecular weight natural heteropolymer present in the cells of several plants, and consist mainly of galacturonic acid and galacturoninc acid methyl ester units forming linear chains, it is classified according to its degree of esterification (DE or DM) .
Pectin content is extracted from the albedo part of the peel of some citrus fruit like lemons and limes, and can be obtained also from apple pomace, the residue of apple juice pressing.
In High Methoxyl – HM pectins a relatively high portion of carboxyl groups occur as methyl esther, in Low Methoxyl pectins – LM less than 50% of the carboxyl groups are esterified. Low Methoxhyl Amidated pectins – LMA are similar to the LM ones, although some of the carboxyl groups are amidated.
The lower the DM the higher the calcium reactivity of the pectin will be.
HM pectins require a sytem with at least 55% of solids to gel.
LM pectins as a result of their lower than 50% DM, gel only in presence of Calcium ions, but can also gel in presence of sugars and acids though their disctinctive feature is the ability to gel in low soluble solid conditions, by carefully balancing pH, solids and calcium content various texures can be achieved.
LMA pectins form gel the same way as LM pectins but with a moderate calcium rectivity showing a much greate rtolerence to changes in calcium leves and driving to gels that are more thermally reversible and able to reform after shearing.
Pectins are perceived from the consumers probably as the most natural among food additives.