Dynamic mechanical spectra of salep and casein mixtures.

In this study, a glucomannan based salep and casein were mixed in a solution at different concentrations (0-0.75% salep and 0-3.0% casein) according to the central composite rotatable design and their color, steady shear and dynamic shear rheological properties were characterized. All studied parameters were affected by the salep and casein levels significantly. Salep increased the apparent viscosity, consistency coefficient, storage modulus and complex modulus of the solution compared to casein and an interaction was observed between the salep and casein which shows a significant increasing effect on the parameters. Frequency dependency increased with the increase of casein in the mixtures. Regression equations having quite high coefficients of determination were constructed for the estimation of studied parameter levels. Optimization performed with desirability function showed that the maximum levels for the rheological parameters could be achieved by more increment of salep level in the solutions because sole effect of casein on the rheological parameters was limited compared to salep.