Location: Quality & Safety Assessment Research2011 Annual Report
1a. Objectives (from AD-416)
1. Develop methods and instruments to identify food safety hazards throughout various stages of poultry and egg production and processing. 2. Detect and characterize foodborne pathogens, toxins, and bacterial threat agents with rapid optical methods. 3. Develop and evaluate detection methods for foodborne pathogens and toxins with nanotechnology.
1b. Approach (from AD-416)
Various optical (imaging) methods will be used for detecting intentional and unintentional contaminants and bacterial pathogens of food products. A real-time in-line hyperspectral imaging system will be used to rapidly detect diseased and contaminated broiler carcasses in processing plants. A monochromatic imaging system will be used for detecting cracks in table and hatching eggs. Hyperspectral microscopic imaging system, Raman imaging instrument and Fourier transform infrared spectrometer will be used to detect biofilms and foreign materials on the surfaces of food processing equipment. Visible/near-infrared hyperspectral imaging systems will be used to rapidly detect and characterize foodborne pathogens associated with poultry products and bacterial threat agents. Nanotechnology will be used for detection of foodborne pathogens and toxins. Collaboration with ARS Environmental Microbial and Food Safety Laboratory, BARC, FSIS, AMS, and the University of Georgia Nano Science and Engineering Center will be used to enhance the research.
3. Progress Report
Screening Non-O157 Shiga Toxin-producing E. coli Serotypes on Agar Media by Hyperspectral Imaging. Six serotypes of enterohemorrhagic Escherichia coli (O26, O111, O45, O121, O103, and O145) other than serotype O157:H7 have been identified as a serious threat to food safety. Screening these pathogens grown on agar plates is not effective because fermentable carbohydrates sources for discrimination are not available. A hyperspectral imaging technique was developed to discriminate each of the 6 serotypes on rainbow agar plates. The method will aid the analyst by reducing the number of colonies picked for further conformational testing. Acousto-Optic Tunable Filter Hyperspectral Microscope for Foodborne Pathogenic Bacteria Detection. A hyperspectral microscope imaging system could be an effective tool to understand the optical properties of foodborne pathogenic bacteria at the cell level. A hyperspectral microscope imaging method was developed for image acquisition with a dark field illumination light source. Salmonella, E.coli and biofilms were tested and their spectral characteristics were analyzed to identify spectral characteristics of different bacteria. Further development of this technique could be used for in-situ foodborne pathogen detection. Rapid Detection of Salmonella using Surface Enhanced Raman Spectroscopy (SERS) with Silver Nanorods. SERS with silver nanosubstrate deposited on thin titanium coated glass slides can improve sensitivity for pathogen detection. Salmonella typhimurium were tested in the forms of live and dead cells. Spectra from the cells on the silver nanosubstrate were acquired with a confocal Raman microscope. Spectral signatures of the dead and live cells were compared to differentiate them. The spectral signatures from each cell type indicated structural changes in bacteria cell components. Thus, the SERS method could differentiate between live and dead bacteria cells.
1. Shiga toxin-producing Escherichia coli (STEC) Detection on Agar Plates. Culture methods as a presumptive positive screening tool of non-O157 Shiga toxin-producing Escherichia coli (STEC) are time-consuming and not effective in testing large amount of food samples. A hyperspectral imaging method has been under development to discriminate each of 6 non-O157 Shiga toxin-producing Escherichia coli (STEC) serotypes (O26, O111, O45, O121, O103, and O145) on agar plates. Spectral libraries of pure pathogens cultures on agar plates were built and classification models were developed. Tests with Rainbow agar plates showed the potential of the imaging technique for rapid screening of food samples contaminated by Shiga toxin-producing Escherichia coli (STEC) organisms.
Berrang, M.E., Windham, W.R., Meinersmann, R.J. 2011. Campylobacter, Salmonella and Escherichia coli on broiler carcasses subject to a high pH scald and low pH postpick chlorine dip. Poultry Science. 90(4):896-900.