Detection and differentiation of live and heat-treated Salmonella enterica serovars inoculated onto chicken breast using Fourier transform infrared (FT-IR) spectroscopy

Aims:- To evaluate Fourier transform infrared (FT-IR) techniques for detecting, quantifying, and differentiating viable and heat-treated cells of Salmonella enterica serovars from chicken breast.Methods and Results:- Salmonella enterica serovars were captured from inoculated chicken breast by filtration and immunomagnetic separation (IMS) prior to spectral collection using an FT-IR spectrometer and IR microscopy. The detection limits, based on amide II peak area (1589 to 1493-cm^-1), for the Filtration-FT-IR and IMS-FT-IR methods were 10⁶ and 10⁴-CFU-g^-1, respectively. The bacteria were detectable after 6-h of culture enrichment during a sensitivity experiment with lower initial inoculum of 10^1-CFU-g^-1. Canonical variate analysis differentiated experimental from control spectra at a level of 10^3-CFU-g^-1. Partial least squares models were established for the quantification of Salm. enterica from chicken breast using Filtration-FT-IR (R²-≥-0.95, RMSEC-≤-0.62) and IMS-FT-IR (R²-≥-0.80, RMSEC-≤-1.61) methods. Filtration-FT-IR was also used to detect and quantify live Salm. enterica in the presence of heat-treated cells with R²-=-0.996, and this approach was comparable to the results of a commercial stain (BacLight™; R^2-=^-0.998). Discriminant and canonical variate analyses of the spectra differentiated live and dead cells of different serovars of Salm. enterica.Conclusions:- FT-IR analysis coupled with separation methods is useful for the rapid detection and differentiation of Salm. enterica separated from chicken.Significance and Impact of the Study:- FT-IR-based methods are faster than traditional microbiological methods and can be used for the detection of live and dead bacteria from complex foods.