Visible spectral imaging (443–726 nm) for evaluating ultraviolet decontamination and predicting bacterial spoilage of vacuum packed chicken breasts

This work used portable spectral imaging to assess effects of ultraviolet (UV) (254 nm) decontamination and predict bacterial spoilage of vacuum packaged chicken breasts. Samples were scanned using spectral imaging, sampled for colour (L* - lightness, a* - redness, b* - yellowness), pH, total viable (TVC) and total Enterobacteriaceae counts (TEC) over 12 days of storage at 4 °C. UV treated samples had mean a* values 0.42 units significantly higher than untreated controls (p < 0.05). UV treatment affected the spectra of samples, allowing for discrimination between treatment types using Partial least squares discriminant analysis (PLS-DA) (CC%<inf>test</inf> = 97.5%). Values of TEC and TVC were significantly reduced by UV treatment and the effects remained significant over the storage time (p < 0.05), extending bacterial shelf life by 3 days. Partial least squares regression (PLSR) models were built from the measured spectra to predict TEC (R<inf>p</inf>² = 0.66, RMSEP = 0.63 log CFU/g) and TVC (R<inf>p</inf>² = 0.78, RMSEP = 0.87 log CFU/g). Interpretation of the spectra strongly suggested that UV treatment affected oxymyoglobin concentrations by accelerating myoglobin oxidation. However, despite differences in oxymyoglobin concentrations, it was still possible to build models using spectral data that could reasonably predict microbiological spoilage.