Abstract
AKNOWLEDGE of the properties of the peetic compounds present in fruits and other plant tissues is of considerable practical interest: thus they play an important part in the setting of jams, in the fermentation processes of wine, beer, and cider, and in the preparation of textile fibres. They undergo changes during the ripening and senescence of frit or with the onset of disease, and hence are closely connected with problems of storage. Branfoot,1 in a recent review of these compounds, classifies them into five groups: pectose is an insoluble compound of cellulose and pectin, present in the cell walls of tissues; it is of variable composition, since a variable number of the methoxy groups of pectin may be replaced by cellulose residues. Pectin is a neutral methoxy ester of pectic acid, and contains 11.76 per cent methyl alcohol; pectinic acids are intermediate between pectin and pectic acid, simple carboxyl groups replacing those esterified with methyl alcohol. Pectic acid is a complex of four molecules of galacturonic acid and one each of arabinose and galactose; methylpentose is possibly present in some pectic acids. Pectic acid forms salts of definite composition, of which that with calcium is insoluble and is useful in the estimation of the pectin content of plants. The simplest compound of the group is metapectic acid, which appears to be d-galactose-galacturonic acid.
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The Pectic Substances of Plants. Nature 124, 709 (1929). https://doi.org/10.1038/124709a0
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DOI: https://doi.org/10.1038/124709a0