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vol. 13, nr. 1 (2009)
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Application of vane impeller for assessment of rheological properties of poultry liver paté
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Fabian Dajnowiec, Lidia Zander
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Department of Process Engineering and Equipment, Faculty of Food Science Olsztyn University of Warmia and Mazury ul. Oczapowskiego 7, 10-957 Olsztyn |
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vol. 13 (2009), nr. 1,
pp. 29-38
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abstract:
Rheological properties of market-available liver paté spreads were investigated using a vane impeller (d = 20.5 mm, h = 41.6 mm) and the drive system of a rotational rheometer Rheotest RV2. The measurement of the shear stress , developed on the walls of the cylinder, formed by the vane rotation, enabled evaluation of the static yield stress y and flow curves of the samples tested. The measurements were carried out at temperatures of 10, 15, 20 and 50oC. The spreads tested displayed variable water content over the range of 65.0-69.7 g (100 g)-1 and fat content from 10.7 to 20.6 g (100 g)-1. Static yield stress value y of the samples varied from 45 to 130 Pa and depended upon the sample and temperature. The flow curves were typical for shear-thinned fluid possessing yield stress, and suggested good agreement with the concept of so-called ideal spread. This term means a material possessing yield stress sufficient to keep its shape under its own weight while simultaneously displaying relatively low apparent viscosity. Over a wide range of shear rates the relationship was linear and for its approximation the Bingham equation could be applied. The experiments have shown significant viscosity differentiation between the spreads obtained by various manufacturers, and applicability of the vane impeller for spread-ability evaluations.
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keywords:
liver paté, plastic viscosity, vane rheometry, yield stress
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original in:
English
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