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 behaves as a non-Newtonian pseudo-plastic fluid. Seven models namely, Power-law, Herschel – Bulkley, Casson, Bingham, Vocadlo, Mizrahi & Berk, and O’foli 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. Also, the optimized sample consisting of 1% from both types of emulsifying mixtures was found the most consistent one.

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