Application of WLF and Arrhenius Kinetics to Rheology of Selected Dark‐colored Honey

Abstract

The rheological properties of Common Black Horehound, Globe Thistle, and Squill types of dark‐colored Jordanian honey were examined. The types of honey used were identified via assessing the source of nectar using pollen analysis (Melissopalynology). The apparent viscosity, η, was measured as a function of the shear rate, γ. In addition, the apparent viscosity was measured, at constant shear rate (6.12 s−1), as a function of shearing time. Newton's law of viscosity (i.e., τ=ηγ) was found to adequately (R2∼ 0.99) describe the flow behavior of honey samples. The apparent viscosity was found to decrease with temperature, and the temperature dependence of viscosity was contrasted versus both Arrhenius model (η=ηoeEa/RT) and WLF model (η/ηG= 10 (C1(T–T)/C2+(T–TG))). Although Arrhenius kinetics may fit the viscosity versus temperature data for the examined types of honey, nevertheless, it gives a relatively high value of activation energy that is quite comparable with, if not even larger than, that of a typical chemical reaction. On the other hand, WLF‐model was found to adequately describe the data while at the same time it gives quite reasonable values of both TG and ηG, which are in agreement with those cited in literature.

Composition, thermal and rheological behaviour of selected Greek honeys

“…All data sets could be fitted to a single master curve using the WLF model with the fixed Ôuniversal' constants, C 1 ¼ 17:44 and C 2 ¼ 51:6 K (Williams et al, 1955). These results concur with the findings of Al-Malah et al (2001) who also found that the WLF equation, using the Ôuniversal' constants, adequately described the temperature-dependence of viscosity for three honey samples. The Ôuniversal constants' of the WLF equation are actually average values, which have been extracted from data on numerous glass-forming liquids and their use is not successful for all materials.…”

“…Although the Arrhenius formalism seems to adequately describe the temperature dependence of honey viscosity, it gives relatively high values for the activation energy, which are more typical of chemical reactions. Similar observations concerning the magnitude of E a derived from viscosity data of three Jordanian honey samples (E a 95.6-97.7 kJ mol À1 , temperature range 20-50°C) have been made in a previous study by Al-Malah et al (2001).…”

“…hydroxymethylfurfural, HMF) degradation and thus it would be useful the prediction of viscosity changes under these conditions. The WLF equation has been previously found to adequately describe viscosity data of Jordanian (temperature range 20-50°C; Al-Malah et al, 2001) and Australian (temperature range 2-40°C; Sopade et al, 2002) honeys.…”

High-Pressure Processing of Manuka Honey: Improvement of Antioxidant Activity, Preservation of Colour and Flow Behaviour

“…Although thermal processing is a convenient way to change the consistency of honey and protect it from fermentation (since an increase of water activity during crystallization tends to ferment), high temperature can be detrimental to the quality of honey and its biological properties. Most type of honey show Newtonian behaviour (Bhandari et al 1999;Al-Malah et al 200 1;Zaitoun et al 200 1;Abu-Jdayil et al 2002); however, there are some reports in the literature showing a nonNewtonian behaviour of honey (Munroe 1943;White 1978). Thermal treatment will change the flow behaviour of honey.…”

Rheological Properties of Some Honeys in Liquefied and Crystallised States

“…The subject has been widely studied and there is extensive literature available on the rheological properties of the honey collected in different parts of the world (Bhandari et al, 1999, Gómez-Díaz et al, 2006, Kayacier & Karaman, 2008Lazaridou et al, 2004;Mossel et al, 2000, Oh & Yoo, 2011Trávníček et al, 2012;Yoo, 2004,). Most of the reports on the subject maintain that honey is a Newtonian fluid whose viscosity depends on temperature and water content (Abu-Jdayil et al, 2002;Al-Malah et al, 2001;Bakier, 2007;Junzheng and Changying, 1998;Sopade et al, 2002;Yanniotis et al, 2006;Zaitoun et al, 2001). Some works indicate that liquid honey may have pseudoplastic properties (Gomez-Diaz et al, 2006;Mehryar et al, 2013) or thixotropic characteristics (White, 1978).…”