Biological fluids such as food boluses are complex fluids which often are inhomogeneous, change over time and have a limited linear region. The rheological properties of a food bolus determine how easy it is to swallow which is crucial for those suffering from swallowing disorders. It is advantageous to use Fourier transform rheology to quickly obtain the mechanical spectrum of a bolus as it changes over time. Several harmonic strains are superimposed, and the resulting stress response is transformed into a mechanical spectrum. A novel optimisation algorithm was applied to minimise the maximal strain and strain rate applied to the sensitive bolus sample. The time to obtain a mechanical spectrum was reduced from 10 to 3.5 minutes.