sources and Extraction
Pectin is found in most plants, but is most concentrated in citrus fruits (oranges,
lemons, grapefruits) and apples. Pectin obtained from citrus peels is referred to as citrus
pectin.
The extraction of pectins can lead to large variations in the chemical structure of the
final material. Pectins are industrially extracted from citrus peels and apple pomace by hot
acidified water. Extraction conditions of pH 1.5 to 3.0 and temperatures of 60-100 C for 0.5 to
6 hours are varied to give a material that has the desired gelling capacity and degree of
methylation. The separation of the viscous material from the swollen and partially
disintegrated plant material remains a problem. Grinding and washing with ethanol are used
but this can lead to co-precipitation with intracellular proteins, starches and nucleic acids.
Another method by which this contamination may be avoided is by wet ball milling at low
temperature. Enzymatic degradation of the pectin is avoided by addition of a surfactant like
sodium dodecyl sulphate (SDS). Sodium deoxycholate (SDC) is used dilute to remove
pigments and lipids and a treatment with 90% dimethyl sulphoxide (DMSO) will remove the