Large deformation behavior of fat crystal networks

Compression and wire-cutting experiments on dispersions of fully hydrogenated palm oil in sunflower oil with varying fraction solid fat were carried out to establish which parameters are important for the large deformation behavior of fat crystal networks. Compression experiments showed that the apparent Young's modulus, yield stress, yield deformation and Bingham extensional viscosity scaled with the volume fraction solid fat according a power law. For the Young's modulus and yield stress, the exponent was about 3.8-3.9. The scaling exponent is close to the one relating the storage modulus and the fraction solid fat at deformations within the linear region. The specific fracture energy obtained from wire cutting also increased with volume fraction solid fat. That of a 10% solid fat dispersion was about 4 J/m(2). Combination of the energy input from compression experiments and the specific fracture energies from wire-cutting experiments yielded defect lengths of the order of 20 mu m. This length scale corresponds to the size of a fat crystal aggregate at the gel point.