Rheological Properties of Chocolate Pistachio

Subject Areas : Microbiology

S. Khorasani ¹ , M. H. Azizi ² , M. Eshaghi ³

1 - Department of Food Science & Technology, Tarbiat Modarres University, Tehran, Iran
2 - Department of Food Science and Technology, Tarbiat Modares University, Tehran, Iran
3 - Department of Food Science and Technology, Halva Oghab Company, Tehran, Iran

Received: 2015-10-08 Accepted : 2015-10-08 Published : 2014-09-01

Keywords: Pistachio paste, Chocolate pistachio, Non-Newtonian, power law, Pseudo plastic behavior,

Abstract :

This research aimed to assess and determine rheological properties of chocolate pistachio produced from various volumes of monoglycoside (1% and 2%), date powders (34, 38 and 42%) and pistachio pastes. The analyses were performed at temperaturesof 45 ºC, 65 ºC after 3 and 5 hours of processing. These products were found to exhibit nonNewtonian, pseudo-plastic behavior at all treatments. Apparent viscosities versus speed data were successfully fitted to a power law model. The flow behavior index, n, varied in the range of 0.8-0.94. The consistency index, k, was in the range 101.495-167.738 pa - s n . According to statistical analysis, the exponential model was a better model to describe the effect of the soluble solids on the viscosity of chocolate pistachio containing varying percentages of date powder. The activation energy (Ea) was 446.2-41330 j/mol.