Raman spectroscopy for virus detection and the implementation of unorthodox food safety

Food-mediated transmission of pathological viruses is an enduring issue in food safety and public health. The globalization of manufacturing and supply chains has worsened the situation. A containable food-related disease, if not sensed early, could quickly escalate into a global calamity. To control the spread of these infectious diseases, especially when their route of transmission is unknown, timely detection of the causal virus for determining its origin and accurate diagnosis is as crucial as, if not more than medical interventions. The challenges for the developers of such detection methods are sensitivity, specificity, and beyond. Raman spectroscopy provides characteristic information of molecular vibrations for analytes ranging from small molecules to biological compounds and cells. The sensitivity of Raman spectroscopy has improved over time. Confocal Raman technique, surface-enhanced Raman scattering, and coherent anti-Stokes Raman scattering are now available for use in food inspection. We conduct a systematic and comprehensive survey of recent studies on Raman spectroscopic techniques aimed at detecting viruses. Reports relating to the implementation of food safety, either intended or incidental, are selected and reviewed. The basic concepts of the involved Raman techniques are described and compared. And their applications to specific viruses and diseases are summarized. The detection of viruses by Raman scattering takes either the nanotag or label-free approach. The competitive advantages of Raman spectroscopy allow rapid acquisition of spectral data, with minimal sample preparation and the applicability to point-of-care testing. Some of the reviewed methods are highly sophisticated. However, neither approach is free from limits. The emerging challenges and perspectives of the further development of Raman spectroscopic techniques in food-adherent pathogen testing are discussed and concluded.