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Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 18975
Title Studies on the structure of industrial high methoxyl pectins
Author(s) Kravtchenko, T.P.
Source Agricultural University. Promotor(en): W. Pilnik; A.G.J. Voragen. - S.l. : Kravtchenko - 173
Department(s) Food Chemistry and Microbiology
Publication type Dissertation, internally prepared
Publication year 1992
Keyword(s) pectinen - polychloorbifenylen - chemische structuur - pectins - polychlorinated biphenyls - chemical structure
Categories Organic Chemistry

The chemical structure of three industrial high methoxyl pectins (one extracted from apple pomace and two from lemon peels) has been extensively investigated. The apple pectin differs from the lemon ones by having a higher apparent molecular size, a higher neutral-sugar content, present either as covalently-linked side chains or as free neutral polysaccharides, a higher acetyl content and a higher phenolic content but a lower protein content. The lemon pectins appear to be very similar to each other except for their calcium cation content. Preparative size exclusion chromatography and ion exchange chromatography show that pectin samples are not homogeneous and that within one pectin preparation, the composition of pectin molecules varies with their molecular size or ionic charge. The lemon pectin sample richer in calcium cations contains a higher proportion of molecules with low degree of esterification, probably explaining its higher tendancy to form aggregates in the presence of calcium. Enzymic degradation of the pectin samples and subsequent analysis of the resulting fragments showed that at least part of the non-esterified carboxylic acids are grouped in blocks. However, such blocks are more numerous in the lemon pectin that is richer in calcium cations than in the apple or the other lemon pectin. Their presence explains the higher calcium-sensitivity of certain pectins and thus strongly influences their physical behaviour on application.

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