A chemometrics approach applied to Fourier transform infrared spectroscopy (FTIR) for monitoring the spoilage of fresh salmon (Salmo salar) stored under modified atmospheres

• Published in: International journal of food microbiology Vol. 241; pp. 331 - 339
• Main Authors: Saraiva, C., Vasconcelos, H., de Almeida, José M.M.M.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 16.01.2017; Elsevier BV
• Subjects: Animals; Atmosphere; Bacteria; Bacteria - growth & development; Bacteria - isolation & purification; Carbon dioxide; Chemometrics; Discriminant analysis; Enumeration; Fillets; Fish Products - analysis; Fish Products - microbiology; Food Contamination - analysis; Food Preservation; Food Storage; Fourier transforms; Freshness; Fungi - growth & development; Fungi - isolation & purification; Humans; Hydrogen sulfide; Infrared analysis; Infrared spectra; Infrared spectroscopy; Lactic acid; Lactic acid bacteria; Lemon juice; Microorganisms; MIR spectroscopy; Modified atmospheres; Multivariate analysis; Multivariate calibration; Packaging; pH effects; PLS regression; Principal components analysis; Regression analysis; Salmo salar; Salmo salar - microbiology; Salmon; Salmon shelf life; Spectroscopy; Spectroscopy, Fourier Transform Infrared - methods; Spoilage; Taste; Yeasts; Yeasts - growth & development; Yeasts - isolation & purification; Packaging; MIR spectroscopy; PLS regression; Lemon juice; Salmon shelf life; Multivariate calibration
• ISSN: 0168-1605; 1879-3460
• DOI: 10.1016/j.ijfoodmicro.2016.10.038

The aim of this work was to investigate the potential of Fourier transform infrared spectroscopy (FTIR) to detect and predict the bacterial load of salmon fillets (Salmo salar) stored at 3, 8 and 30°C under three packaging conditions: air packaging (AP) and two modified atmospheres constituted by a mixture of 50%N2/40%CO2/10%O2 with lemon juice (MAPL) and without lemon juice (MAP). Fresh salmon samples were periodically examined for total viable counts (TVC), specific spoilage organisms (SSO) counts, pH, FTIR and sensory assessment of freshness. Principal components analysis (PCA) allowed identification of the wavenumbers potentially correlated with the spoilage process. Linear discriminant analysis (LDA) of infrared spectral data was performed to support sensory data and to accurately identify samples freshness. The effect of the packaging atmospheres was assessed by microbial enumeration and LDA was used to determine sample packaging from the measured infrared spectra. It was verified that modified atmospheres can decrease significantly the bacterial load of fresh salmon. Lemon juice combined with MAP showed a more pronounced delay in the growth of Brochothrix thermosphacta, Photobacterium phosphoreum, psychrotrophs and H2S producers. Partial least squares regression (PLS-R) allowed estimates of TVC and psychrotrophs, lactic acid bacteria, molds and yeasts, Brochothrix thermosphacta, Enterobacteriaceae, Pseudomonas spp. and H2S producer counts from the infrared spectral data. For TVC, the root mean square error of prediction (RMSEP) value was 0.78logcfug−1 for an external set of samples. According to the results, FTIR can be used as a reliable, accurate and fast method for real time freshness evaluation of salmon fillets stored under different temperatures and packaging atmospheres. •It is demonstrated that FTIR can predict spoilage in fresh salmon fillets.•Relationships between deteriorative microbiota and pH and FTIR data were established.•Spectroscopic measurements were correlated with sensory analysis of freshness.•Using multivariate regressions, Pseudomonas spp. counts were predicted from FTIR data.•Lemon juice can decrease significantly the bacterial load of fresh salmon.