In this paper, performance evaluation of the centrifugal peeling system for pistachio nuts was studied as a function of moisture content (in five levels: 4.10, 10.50, 28.50 and 36.10 % d.b) and peripheral speed of separate rotating circular base – plate (in four levels: 35, 40, 45 and 50 m/s) in a factorial design based on completely randomized block. The overall performance was expressed in terms of peeling efficiency and breakage percent. Peeling efficiency and breakage increased with (i) increase in peripheral speed (ii) decrease in the pistachio moisture content. The results of an optimization technique revealed that the best peeling performance could be obtained if the machine is operated at peripheral speed of 50 m/s and moisture content of 4.10 % d.b. Under these conditions, the values of peeling efficiency and breakage percent were 96.5 and 8.7 %, respectively.

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