Effects of formulation and processing conditions on the physical properties of fat crystal networks
This thesis investigates the effects of formulation and processing conditions on the material properties of fat crystal networks. A scraped surface heat exchanger was used to control crystallisation and to produce fat crystal networks. Experiments were conducted to study the effects of formulation (solid fat composition) and processing conditions (scraped surface heat exchanger's mixing speed, coolant temperature, and throughput). Rheological studies were conducted to characterise the material properties of the fat systems. Viscosity measurements were carried out to study the effects of processing conditions on the material behaviour whilst oscillatory rheology was used to study the viscoelastic behaviour of the fat systems. Amplitude sweeps and oscillation tests (small scale rheological analysis) were conducted to study the viscous modulus (G”) and the elastic modulus (G') of the system which is an indicator of the macroscopic consistency of the network. Polarised light microscopy (PLM) was employed to observe the microstructure of the crystallised system. These images were used alongside image analysis software, ImageJ, to quantify the complexity of the microstructural level of the fat crystal networks by calculating their box-counting fractal dimensions (D\(_b\)). The thermal behaviour of fat systems was studied using differential scanning calorimetry (DSC).