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Determination of unmodified methionine and methionine sulphoxide in food proteins by gas–liquid chromatography
Author(s) -
Duncan Alexander,
Ellinger Gabrielle M.,
Glennie Robert T.
Publication year - 1984
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.2740350119
Subject(s) - methionine , chemistry , performic acid , chromatography , gas chromatography , hydrogen peroxide , ion chromatography , methionine sulfoxide , amino acid , organic chemistry , biochemistry
A method for the reduction of methionine sulphoxide to methionine using titanium trichloride is described. This method, coupled with the gas chromatographic determination of methionine after reaction with CNBr, measures methionine sulphoxide by the increase in methionine values after reduction with titanium trichloride. Results obtained for total methionine by gas chromatography after reduction and CNBr reaction, showed close agreement with those obtained by ion‐exchange chromatography after performic acid oxidation. This method was applied to pure proteins which had been subjected to hydrogen peroxide oxidation, and to a wide range of food proteins. An evaluation of other, but less effective, reducing agents is briefly discussed.