OPTICAL DETECTION OF FOOD SAFETY AND FOOD DEFENSE HAZARDS
Location: Quality and Safety Assessment Research Unit
Title: Differentiation of live and dead salmonella cells using fourier transform infrared (FTIR) spectroscopy and principle component analysis (PCA) technique
Submitted to: American Society of Agricultural and Biological Engineers
Publication Type: Abstract Only
Publication Acceptance Date: January 5, 2011
Publication Date: August 6, 2011
Citation: Sundaram, J., Park, B., Hinton Jr, A., Windham, W.R., Yoon, S.C., Lawrence, K.C. 2011. Differentiation of live and dead salmonella cells using fourier transform infrared (FTIR) spectroscopy and principle component analysis (PCA) technique [abstract]. American Society of Agricultural and Biological Engineers. ASABE meeting, August 3-7, Kentucky, USA.
Interpretive Summary: Various technologies have been developed for pathogen detection using their optical, electrochemical, biochemical and physical properties. Since food is a complex materials it is difficult to detect pathogens present in it directly. It takes more time in sampling and identification using traditional methods. In food quality control and safety practices, rapid detection and identification of pathogens has been needed very much. In recent years physicochemical methods of identifying the organisms and its characterization is getting significant attraction. Fourier transform infrared spectroscopy (FTIR) has been used by many researchers for rapid detection, identification and characterization of pathogens. Salmonella typhimurium and Salmonella entritidis food pathogens were selected for this study and they were prepared as live and dead cells. Principle Component Analysis was carried to differentiate the live and dead cells and classify the Salmonella typhimurium and Salmonella entritidis live cells in to different groups.
Various technologies have been developed for pathogen detection using optical, electrochemical, biochemical and physical properties. Conventional microbiological methods need time from days to week to get the result. Though this method is very sensitive and accurate, a rapid detection of pathogens is very much in need these days. In this study FTIR method was developed to detect and classify Salmonella typhimurium and Salmonella entritidis, common food pathogens, into different groups. Bacteria cells were prepared in the forms of live and dead cells. These cells were loaded on the ZnSe ATR crystal surface (45' ZnSe, 10 bounces and 48 × 5 mm effective area of analysis on the crystal), scanned and spectra were recorded from 4000 cm-1 to 400 cm-1 wave number. Spectral signatures of different forms of Salmonella cells were compared to differentiate them. Data analysis was carried to detect the live and dead bacteria cells using chemometrics. Principle Component Analysis (PCA) models were developed to establish the relationship between the dead and live bacterial cells and the FTIR spectral signatures to differentiate the live and dead cells. These spectral signatures showed the structural changes in the bacteria cells. The best PCA prediction model was selected based on the R2 (> 0.95) and SEP (< 1.0) values. The results showed that it could be possible to differentiate the live and dead bacteria cells using FTIR spectroscopic methods.