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 10¹ CFU g⁻¹. Canonical variate analysis differentiated experimental from control spectra at a level of 10³ 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™; R² = 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.