Differentiation of rye and wheat flour as well as mixtures by using the kinetics of Karl Fischer water titration

•New Karl Fischer water titration (KFT) approach to the discrimination of rye–wheat flour.•“Surface” and “strongly-retained” water are different in rye and wheat flour.•KFT parameters well correlate with the rye–wheat ratio.•KFT kinetic parameters can be indicators for quality and adulteration of rye–wheat flour.

The aim of this study was to find a simple way to differentiate between rye and wheat flour and their mixtures by using the kinetic parameters of Karl Fischer water titration (KFT). Consequently, the water content and type of molecules in rye and wheat mixtures used in Romanian bread making have been investigated by means of volumetric KFT. Further, the kinetics of KFT have been determined and novel kinetic parameters corresponding to “surface” and “strongly-retained” water molecules have been identified to discriminate between rye and wheat flour and their mixtures. The “surface” and “strongly-retained” water reaction rates well correlate with the rye content in the flour mixtures, especially at higher temperature analysis (r > 0.95). These parameters can be used as indicators for quality evaluation of such type of mixtures, as well as to identify adulteration by improper use of the rye–wheat flour ratios in bread making.