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The reaction of wheat proteins with sulphite. I.—Sulphitolysis of the proteins of flour with cuprammonium sulphite
Author(s) -
McDermott E. E.,
Pace J.
Publication year - 1965
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.2740160707
Subject(s) - chemistry , deamidation , residue (chemistry) , starch , wheat flour , organic chemistry , biochemistry , amino acid , carbohydrate , food science , chromatography , enzyme
The reaction of wheaten flour and of some flour protein fractions, with cuprammonium sulphite solutions at pH 10·2 has been investigated. Under these conditions, with a reaction time of 2–4 h. at room temperature, the thiol and disulphide groups of the flour proteins are completely converted to S ‐sulphocysteine residues and the proteins dissolve, together with some carbohydrate. The insoluble residue is a high quality starch. The effect of the sulphitolysis procedure on the amide groups of the proteins, in flours of widely different protein content, has been examined and there was no evidence that deamidation had occurred. Similarly the amino‐acid composition of a flour protein fraction remained unchanged by the sulphitolysis procedure. In these respects the specificity of the reaction confirmed the original observations of Swan with keratin, but evidence obtained by prolonging the reaction time suggests that with flour proteins, some disaggregation or cleavage of their structure, other than that due to the splitting of disulphide bonds, may also occur and this possibility is being investigated in further work. Some general properties of the solubilised material are described.