Properties of amylose-iodine complexes prepared in the presence of excess iodine

A potentiometric-titration procedure, in which samples are always exposed to an excess of I 2-KI has been developed for measuring iodine-binding capacity of starches. Binding capacity of amylose under these conditions is ∼30% as opposed to 20% by conventional potentiometric titration. Spectrophotome...

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Bibliographic Details
Published in:Carbohydrate research 1982-01, Vol.101 (1), p.117-128
Main Authors: Knutson, Clarence A., Cluskey, James E., Dintzis, Frederick R.
Format: Article
Language:English
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Summary:A potentiometric-titration procedure, in which samples are always exposed to an excess of I 2-KI has been developed for measuring iodine-binding capacity of starches. Binding capacity of amylose under these conditions is ∼30% as opposed to 20% by conventional potentiometric titration. Spectrophotometric absorbance is essentially the same for either method, but is proportional to potentiometric values only in the excess-iodine titration procedure. Effects of variation of concentration of I 2, KI, and phosphate buffer and of temperature on the reaction have been examined. Calculations based on concentration of reactants in solution indicate that the binding species varies from I 3 − at 10 −1 m KI to I 11 − at 5 × 10 −4 m KI.
ISSN:0008-6215
1873-426X
DOI:10.1016/S0008-6215(00)80800-9