Pistachio butter is a semi-solid paste, which is produced from ground and roasted pistachio kernels. In this study, the flow curves and effect of different levels of emulsifier (Lecithin and Mono-diglyceride) were assessed at different temperatures. It was found that pistachio butter behaved as a non-Newtonian pseudo-plastic fluid with yield stress value. Seven models were used to describe time-independent flow behavior of all samples. To evaluate the ability of these models to predict rheological characteristics of pistachio butter, three statistical parameters namely; R2, RMSE, and MRDM were used and finally Herschel-Bulkley model was found to be the most appropriate to fit the flow curves of pistachio butter. The effect of temperature on the apparent viscosity followed an Arrhenius relationship. Also, the optimized sample consisting of 1% from both types of emulsifying mixtures (0.5% lecithin and 0.5% mono-diglyceride) was found the most consistent one.

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