Effects of surface morphologies of fresh produce on the performance of phage-based magnetoelastic biosensors

This study investigated the effects of different surface morphologies on the performance of phage-based magnetoelastic (ME) biosensors for Salmonella Typhimurium detection on selected fresh produce. The ME biosensor is composed of an ME resonator platform and filamentousE2phage for the specific recognition ofS. Typhimurium. After SEM observation of the surface morphologies of tomatoes and spinach (adaxial/abaxial), S. Typhimurium was inoculated serially onto the surfaces to examine the attachment and distribution of bacterial cells on the surfaces. Finally, the linearity and detection limit of the ME biosensors detecting S. Typhimurium on food surfaces were tested. The morphologies of tomato and spinach surfaces were obviously different due to the existence of stomata and the differences in roughness and curvature. However, there were no obvious differences in attachment and distribution of bacterial cells on the surfaces. The resonant frequency shifts of measurement sensors increased linearly with an increase in the concentration of S. Typhimurium in contrast to relatively constant and negligible shifts of control sensors. Detection limit of the ME biosensor method was determined to be 1.87 log CFU/cm² for the tomatoes, 1.72 log CFU/cm² for the adaxial surface of spinach, and 2.16 log CFU/cm² for the abaxial surface of spinach.