Detection of E. coli O157:H7 from ground beef using fourier transform infrared (FT-IR) spectroscopy and chemometrics

Reeta Davis, Joseph Maria Kumar Irudayaraj, Bradley L. Reuhs, Lisa J. Mauer

Research output: Contribution to journalArticle

Abstract

FT-IR spectroscopy methods for detection, differentiation, and quantification of E. coli O157:H7 strains separated from ground beef were developed. Filtration and immunomagnetic separation (IMS) were used to extract live and dead E. coli O157:H7 cells from contaminated ground beef prior to spectral acquisition. Spectra were analyzed using chemometric techniques in OPUS, TQ Analyst, and WinDAS software programs. Standard plate counts were used for development and validation of spectral analyses. The detection limit based on a selectivity value using the OPUS ident test was 105 CFU/g for both Filtration-FT-IR and IMS-FT-IR methods. Experiments using ground beef inoculated with fewer cells (101 to 102 CFU/g) reached the detection limit at 6 h incubation. Partial least squares (PLS) models with cross validation were used to establish relationships between plate counts and FT-IR spectra. Better PLS predictions were obtained for quantifying live E. coli O157:H7 strains (R2≥ 0.9955, RMSEE ≤ 0.17, RPD ≥ 14) and different ratios of live and dead E. coli O157:H7 cells (R2= 0.9945, RMSEE = 2.75, RPD = 13.43) from ground beef using Filtration-FT-IR than IMS-FT-IR methods. Discriminant analysis and canonical variate analysis (CVA) of the spectra differentiated various strains of E. coli O157:H7 from an apathogenic control strain. CVA also separated spectra of 100% dead cells separated from ground beef from spectra of 0.5% live cells in the presence of 99.5% dead cells of E. coli O157:H7. These combined separation and FT-IR methods could be useful for rapid detection and differentiation of pathogens in complex foods.

Original languageEnglish (US)
JournalJournal of food science
Volume75
Issue number6
DOIs
StatePublished - Aug 1 2010
Externally publishedYes

Keywords

  • E. coli O157:H7
  • Fourier transform infrared spectroscopy
  • Ground beef
  • Immunomagnetic separation
  • Pathogen detection

ASJC Scopus subject areas

  • Food Science

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