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Pectic substances in onion and garlic skins
Author(s) -
Alexander M. M.,
Sulebele G. A.
Publication year - 1973
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740240514
Subject(s) - pectin , chemistry , food science , ammonium oxalate , allium , dehydration , botany , organic chemistry , biochemistry , biology
Pectic substances from onion (white and red varieties) and garlic skins were isolated by extraction with ammonium oxalate. White onion and garlic skins were found to contain 11 to 12% pectin which can be recovered as a by‐product in the dehydration industries. Characterisation of these pectic substances in terms of jelly grade, molecular weight, degree of esterification, methoxyl and uronide content was attempted. Pectins from white onions were superior to red onions in terms of jelly grade. Both types of onion pectins appeared to be of the rapid set type while the garlic skin pectin was of the medium set variety. Equivalent weight, methoxyl content and degree of esterification by themselves did not give any clear indication of pectin grade. Intrinsic viscosity values gave good correlation between jelly grade and molecular weight. The pectic substances from garlic skin differed from onion skin in certain respects and most remarkably in its viscosity behaviour.