Label Free Biosensor Methods in Detection of Food

Food pathogens contaminate food products that allow their growth on the shelf and also 8 under refrigerated conditions. Therefore, it is of utmost importance to lower the limit of detection 9 (LOD) of the method used and to obtain the results within hours to few days. Biosensor methods 10 exploit the available technologies to individuate and provide an approximate quantification of the 11 bacteria present in a sample. The main bottleneck of these methods depend on the aspecific 12 binding to the surfaces and on a change in sensitivity when bacteria are in a complex food matrix 13 in respect to bacteria in a liquid food sample. In this review we introduce Surface Plasmon 14 Resonance (SPR), new advancements in SPR techniques, and Electrochemical Impedance 15 Spectroscopy (EIS), as label-free biosensing technologies for the detection of L. monocytogenes in 16 foods. The application of the two methods has made possible the detection of L. monocytogenes 17 with LOD of 1 log CFU/mL. Further advancement are envisaged through the combination of 18 biosensor methods with immunoseparation of bacteria from larger volumes. 19