@article{paperid:1025182, author = {Razavi, Seyed Mohammad Ali and Taghizadeh, Masoud and Shaker Ardekani}, title = {Modeling the time-dependent rheological behavior of pistachio butter}, journal = {International Journal of Nuts and Related Sciences}, year = {2009}, volume = {1}, number = {1}, month = {January}, issn = {2008-9937}, pages = {32--37}, numpages = {5}, keywords = {Pistachio butter -semi solid paste-; which is made from roasted pistachio kernels; is an appropriate alternative to work on because of its high nutritional and economical values. In this study; time-dependent flow properties of pistachio butter were determined at two different temperatures -25˚C and 45˚C- for five different formulations -with different levels of emulsifying agents-. Forward and backward flow curves were plotted and the amount of existing hysteresis loop was measured. Also; shear stress vs. time of shearing data were assessed using three models namely; Weltman; First-order shear stress decay with a zero equilibrium stress value; and First-order shear stress decay with a non-zero equilibrium stress value. To evaluate the ability of these models to predict the rheological characteristics of pistachio butter; three statistical parameters namely; R2; RMSE; and MRDM were used and finally the Weltman model was found to be the most appropriate to fit the experimental data. The results showed that pistachio butter exhibits a thixotropic behavior and its apparent viscosity decreases with increasing the time of shearing.}, }