Mechanical properties of gelatin-rich micro-particles

Effect of chemical composition and applied strain on mechanical properties of gelled gelatin-rich micro-particles resulting from phase separated gelatin/pullulan mixtures has been investigated. The mechanical properties of micro-particles (20–120 μm) were measured using a micromanipulation technique. The compress–release tests revealed that at a low deformation (up to 10% strain) particles are fully elastic with Young’s modulus proportional to the concentration of gelatin and at the higher deformation (up to 50–80%) particles are visco-elastic. Even at very high load resulting in 50–60% deformation, no fracture of particles was observed and after the load was removed, particles recovered to a fully spherical shape. The visco-elastic behaviour was investigated by a stress-relaxation method, where force relaxation at constant deformation was measured as a function of time. The experimental results were analysed using a standard liner model of visco-elastic solids and the parameters of this model were related to the composition of gelled particles.