SMRs have been used in numerous applications for life science where most samples are contained in liquid. In this work we investigate how a biological medium, such as phosphate buffer solution (PBS), affects the Signal to Noise ratio (SNR) of PZE actuated SMRs. We report that SNR is directly linked to the conductivity of the solution, that is inevitable for biological applications. Furthermore, we look into a novel application for these devices in the food industry, namely the characterization of olive oil. We prove that it is possible to distinguish two different olive oils by analysing the quality factor and resonance frequency, that are linked to the viscosity and density of the fluid.