Biopolymer encapsulated AgNO3 nanoparticle substrates with surface-enhanced Raman spectroscopy (SERS) for Salmonella detection from chicken rinse

Authors: Eady, Matthew; Setia, Gayatri; Park, Bosoon; WANG, BIN - Orise Fellow; Sundaram, Jaya

Submitted to: International Journal of Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/22/2023
Publication Date: 2/28/2023
Citation: Eady, M.B., Setia, G., Park, B., Wang, B., Sundaram, J. 2023. Biopolymer encapsulated AgNO3 nanoparticle substrates with surface-enhanced Raman spectroscopy (SERS) for Salmonella detection from chicken rinse. International Journal of Food Microbiology. https://doi.org/10.1016/j.ijfoodmicro.2023.110158.
DOI: https://doi.org/10.1016/j.ijfoodmicro.2023.110158

Interpretive Summary: Salmonella is foodborne pathogenic bacteria responsible for many gastrointestinal illnesses around the world and the poultry industry has been highly impacted by this pathogen. With increase in per capita consumption from 44 pounds/year in 1965 to 113.3 pounds/year in 2021 comes heightened awareness of Salmonella contamination in poultry meat. In conjunction with new standards of the USDA, Food Safety and Inspection Service an increased vigilance for poultry processors in monitoring and controlling Salmonella contamination is required. Traditional microbial detection methods such as nutrient enriched growth media or polymerase chain reaction (PCR) are the industry standards for identification of foodborne bacteria but have disadvantages such as lengthy incubation times for plating techniques, and the high reoccurring cost of reagent kits for molecular methods. Recently, optical detection methods have incorporated a variety of spectroscopic equipment with the objective of classifying bacteria, based on a spectral signature that is unique to the bacteria. Especially, nanoparticle substrates synthesized from biopolymers have been applied for bacteria detection, in combination with surface enhanced Raman spectroscopy (SERS). In this study, we investigated the potential for Salmonella detection from a chicken rinse, using a portable Raman spectrometer, followed by comparing classification ability to colony morphological traits and PCR. Also, we observed shelf-life stability of nanoparticle substrate, and compared the classification capabilities of the SERS method to traditional microbiological confirmation techniques.

Technical Abstract: Salmonella is commonly found on broiler chickens during processing. This study investigates the Salmonella detection method that reduces the necessary time for confirmation, by collecting surface enhanced Raman spectroscopy (SERS) spectra from bacteria colonies, applied to a substrate of biopolymer encapsulated AgNO3 nanoparticles. Chicken rinses containing Salmonella were analyzed by SERS and compared to traditional plating and PCR analyses. SERS spectra from confirmed Salmonella positive and negative colonies appear similar in spectra composition, but with different peak intensities. T-test on the peak intensities showed that Salmonella positive and negative colonies were significantly different (a = 0.0045) at 5 peaks, 692 cm-1, 718 cm-1, 791 cm-1, 859 cm-1, and 1018 cm-1. A support vector machine (SVM) classification algorithm was able to separate Salmonella positive and negative samples with an overall classification accuracy of 96.7%.