Comparison of rheological models for determining dark chocolate viscosity

Authors

  • Emmanuel Ohene Afoakwa,

    Corresponding author
    1.  Centre for Food Quality, SIPBS, University of Strathclyde, 204 George Street, Royal College Building, Glasgow G1 1XW, UK
    2.  Nestle Product Technology Centre York, P. O. Box 204, Haxby Road, York YO91 1XY, UK
      *E-mail: e.afoakwa@strath.ac.uk
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  • Alistair Paterson,

    1.  Centre for Food Quality, SIPBS, University of Strathclyde, 204 George Street, Royal College Building, Glasgow G1 1XW, UK
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  • Mark Fowler,

    1.  Nestle Product Technology Centre York, P. O. Box 204, Haxby Road, York YO91 1XY, UK
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  • Joselio Vieira

    1.  Nestle Product Technology Centre York, P. O. Box 204, Haxby Road, York YO91 1XY, UK
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  • (Presented at the First International Chester Food Science and Technology Conference, Chester, UK, April 2007)

*E-mail: e.afoakwa@strath.ac.uk

Summary

Parameters in chocolate rheology, namely shear viscosity and yield stress, are important in manufacture and directly influenced by product particle size distribution (PSD) and composition. The Casson model was the standard confectionery industry strategy to quantify rheological properties of molten chocolate until in 2000, the International Confectionery Association recommended the use of interpolation data to describe viscosity. The two strategies are compared and correlated in defining rheological properties of molten dark chocolates prepared using different PSD, fat and lecithin content. Rheological parameters were determined using a shear rate-controlled rheometer and data examined using correlation, regression and principal component analyses to establish their inter-relationships. Correlation and regression analyses showed high correlation (r = 0.89–1.00) and regression coefficients (R2 = 0.84–1.00). The newer International Confectionery Association technique gave higher correlation and regression coefficients than the Casson model, but multivariate principal component analysis showed that the two models were highly related and either could effectively quantify dark chocolate viscosity parameters.

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