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Changes in Molecular Weight of Pectin During Methylation with Diazomethane
Author(s) -
SMIT CHRISTIAN J. B.,
BRYANT EDWIN F.
Publication year - 1969
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1365-2621.1969.tb00916.x
Subject(s) - diazomethane , chemistry , demethylation , pectin , depolymerization , methylation , ether , yield (engineering) , organic chemistry , chromatography , nuclear chemistry , biochemistry , dna methylation , gene expression , materials science , metallurgy , gene
SUMMARY– Acid and enzymatic demethylation procedures suggest that the change in molecular weight during methylation is a result of depolymerization and that a change in the percent methoxyl groups probably has very little effect on the change in molecular weight during methylation or demethylation with pectins having an ester content between 60% and 95%. Samples of a commercially prepared citrus pectin were acid washed, dissolved and neutralized to different levels with dilute NaOH. These samples were treated with isopropanol to yield an open gel‐like precipitate, the alcohol was replaced with ether and the pectin treated with diazomethane at < −30°C. The samples methylated to 70%, 85% and 95% had molecular weight values which decreased with increasing degrees of esterification. Molecular weight was determined by measuring the viscosity of a 0.1 % sol in 1 % Calgon.