Shear Rheology of Molten Crumb Chocolate

Taylor, J.E. and Damme, I. Van and Johns, M. L. and Routh, A. F. and Wilson, D. I. (2009) Shear Rheology of Molten Crumb Chocolate. Journal of Food Science, 74 (2). E55-E61. DOI

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The shear rheology of fresh molten chocolate produced from crumb was studied over 5 decades of shear rate using controlled stress devices. The Carreau model was found to be a more accurate description than the traditional Casson model, especially at shear rates between 0.1 and 1 s22121. At shear rates around 0.1 s22121 (shear stress approximately 7 Pa) the material exhibited a transition to a solid regime, similar to the behavior reported by Coussot (2005) for other granular suspensions. The nature of the suspension was explored by investigating the effect of solids concentration (0.20 < 03C6 < 0.75) and the nature of the particles. The rheology of the chocolate was then compared with the rheology of (1) a synthetic chocolate, which contained sunflower oil in place of cocoa butter, and (2) a suspension of sugar of a similar size distribution (volume mean 15 03BCm) in cocoa butter and emulsifier. The chocolate and synthetic chocolate showed very similar rheological profiles under both steady shear and oscillatory shear. The chocolate and the sugar suspension showed similar Krieger2013Dougherty dependency on volume fraction, and a noticeable transition to a stiff state at solids volume fractions above approximately 0.5. Similar behavior has been reported by Citerne and others (2001) for a smooth peanut butter, which had a similar particle size distribution and solids loading to chocolate. The results indicate that the melt rheology of the chocolate is dominated by hydrodynamic interactions, although at high solids volume fractions the emulsifier may contribute to the departure of the apparent viscosity from the predicted trend.

Item Type: Article
Additional Information: Mars Chocolate, cml
Uncontrolled Keywords: 09AREP; BPI;
Subjects: 99 - Other
Divisions: 99 - Other
Journal or Publication Title: Journal of Food Science
Volume: 74
Page Range: E55-E61
Identification Number:
Depositing User: Sarah Humbert
Date Deposited: 22 Jul 2010 11:25
Last Modified: 23 Jul 2013 09:57

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