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The fate of labelled insecticide residues in food products. II. —The nature of methyl bromide residues in fumigated wheat
Author(s) -
Winteringham F. P. W.,
Harrison A.,
Bridges R. G.,
Bridges Patricia M.
Publication year - 1955
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.2740060503
Subject(s) - chemistry , bromide , decomposition , hydrolysis , wheat flour , fumigation , gluten , starch , sodium hydroxide , methanol , organic chemistry , hydrogen bromide , food science , bromine , agronomy , biology
Abstract The chemical fate of methyl bromide absorbed by wheat under the conditions of fumigation has been studied. Whole‐wheat flour was exposed to 14 C‐labelled methyl bromide. The fat, starch, gluten, and water‐soluble fractions were prepared from the exposed flour and their 14 C‐content assayed. The gluten or protein fraction was responsible for some 80% of the decomposition of the absorbed fumigant. By measuring the 14 C of the volatile products obtained on treating the gluten with sodium hydroxide or hydriodic acid under different conditions, it was shown that the decomposition of methyl bromide in gluten was due almost entirely to methylation with the formation of 50% of N‐methyl derivatives, 30% of dimethyl sulphonium derivatives, and of 20% of methoxyl and thiomethoxyl derivatives in about equal proportions. Similar results were obtained when gluten alone was exposed to the labelled fumigant. The production of free methanol in the flour by hydrolysis of the absorbed fumigant was about 10% or less. The rate of spontaneous decomposition of the dimethyl sulphonium compounds formed as a result of fumigation was estimated by using wheat which had been grown on 35 S‐labelled sulphate.