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Rheological Behaviour and Time Dependent Characterisation of Gilaboru Juice (Viburnum opulus L.)

University of Gaziantep, Food Engineering Department, 27310 Gaziantep, Turkey

S. Kus

University of Gaziantep, Food Engineering Department, 27310 Gaziantep, Turkey

A. Kaya

University of Gaziantep, Food Engineering Department, 27310 Gaziantep, Turkey, kaya{at}gantep.edu.tr

The flow curves and time-dependent rheological behaviour of gilaboru (Viburnum opulus L.), a traditional drink in the middle Anatolia region of Turkey, with different solid concentrations (59.7, 56.3, 53.1, 43 and 35°Brix) were studied at different temperatures (5-60°C) using a controlled stress rheometer. Gilaboru samples exhibited thixotropic behaviour for all concentrations, both in the forward and backward measurements were characterised by the power law. A single equation was proposed for the apparent viscosity 1. Temperature played a major role in determining the magnitudes of the apparent viscosity 1. The completely destructed gilaboru samples flow curves were also measured after subjecting the samples to a high shear rate for 2h. After eliminating thixotropy by shearing, samples showed shearthinning properties that fitted well to the power law model. Three models were used to describe the time-dependent behaviour, namely, the second-order structural kinetic, Weltman and first-order stress decay models. Among the models, the first-order stress decay model fitted well compared to the second- order structural kinetic and Weltman models.

Key Words: Viburnum opulus • gilaboru • thixotropy • rheological modelling

Food Science and Technology International, Vol. 11, No. 2, 129-137 (2005)
DOI: 10.1177/1082013205052763


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