Dark chocolate’s compositional effects revealed by oscillatory rheology

van Der Vaart Kasper (1) , Depypere Frédéric (1) , de Graef Veerle (1) , Schall Peter (2) , Abdoulaye Fall (3, 2) , Daniel Bonn (2) , Koen Dewettinck (1)

1 Laboratory of Food Technology and Engineering
2 Soft Matter Group, Van der Waals–Zeeman Institute
3 navier umr 8205 - Laboratoire Navier

In this study, two types of oscillatory shear rheology are applied on dark chocolate with varying volume fraction, particle size distribution, and soy lecithin concentration. The first, a conventional strain sweep, allows for the separation of the elastic and viscous properties during the yielding. The second, a constant strain rate sweep, where the strain rate amplitude is fixed as the frequency is varied, is analyzed to obtain Lissajous curves, dissipated energy, and higher order nonlinear contributions. It is shown that chocolate exhibits complex nonlinear behavior, namely shear thinning, shear thickening, and strain stiffening. The effects on this behavior related to volume fraction, particle size distribution, and lecithin concentration are investigated, and comparison with simple monodisperse hard-sphere suspensions is made.

Keywords: Oscillatory rheology; Chocolate; Viscoelastic properties; LAOS

Domains: Soft Condensed Matter [cond-mat.soft]; Materials Science [cond-mat.mtrl-sci]

van Der Vaart Kasper, Depypere Frédéric, de Graef Veerle, Schall Peter, Abdoulaye Fall, et al.. Dark chocolate’s compositional effects revealed by oscillatory rheology. European Food Research and Technology, 2013, 236 (6), pp.931-942. ⟨10.1007/s00217-013-1949-2⟩. ⟨hal-01163827⟩