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Determination of Amylose in Flour by a Colorimetric Assay: Collaborative Study
Author(s) -
Martinez Cristina
Publication year - 1996
Publication title -
starch ‐ stärke
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.62
H-Index - 82
eISSN - 1521-379X
pISSN - 0038-9056
DOI - 10.1002/star.19960480303
Subject(s) - repeatability , reproducibility , iodine , amylose , chromatography , starch , chemistry , absorbance , wheat flour , relative standard deviation , urea , organic chemistry , food science , detection limit
An improved colorimetric method, based on the well‐known reaction between amylose and iodine, is described. During a first step, flour is dissolved in dimethylsulfoxide and the starch precipitated with ethanol. The extracted starch is redissolved in urea‐dimethylsulfoxide and the resulting solution defatted with ethanol. An aliquot of the lipid‐free solution is then reacted with iodine and the absorbance of the blue‐coloured amylose‐iodine complex measured, thus determining the iodine‐binding capacity of starch (Blue Value). A collaborative study was conducted, according to official guidelines, to determine the method's repeatability and reproducibility: 9 participants were each sent 7 flour samples from different botanic origin for duplicate analysis. Statistical evaluation of the results showed satisfactory precision, with an average repeatability relative standard deviation of 2.6% and an average reproducibility relative standard deviation of 9.1%. The proposed method can, therefore, be considered as reliable and can be used for routine analysis.