Abstract:
Freshness and safety of muscle foods are generally considered as the most
important parameters for the food industry. It is crucial to validate and establish new
rapid methods for the accurate detection of microbial spoilage of meats. In the current
thesis, the microbial association of meat was monitored in parallel with the chemical
changes, pH measurements and sensory analysis. Several chemical analytical
techniques were applied to explore their dynamics on quantifying spoilage indicators
and evaluate the shelf life of meat products. The applied analytical methods used were
Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, image analysis,
high performance liquid chromatography (HPLC) and gas chromatography/mass
spectroscopy (GC/MS).
The first component of the study was designed to evaluate the potential of FTIR
spectroscopy as a rapid, reagent-less and non-destructive analytical technique in
estimating the freshness and shelf life of beef. For this reason, minced beef samples
survey from the Greek market), beef fillet samples stored aerobically (0, 5, 10, 15
and 20ºC) and minced beef samples stored aerobically, under modified atmosphere
packaging (MAP) and active packaging (0, 5, 10, and 15ºC), were analysed with
FTIR. The statistical analysis from the survey revealed that the impact of the market
type, the packaging type, the day and the season of purchase had a significant effect
on the microbial association of mince. Furthermore, the Principal Components
Analysis (PCA) and Factorial Discriminant Analysis (FDA), applied to the FTIR
spectral data, showed discrimination of the samples based on freshness, packaging
type, the day and season of purchase. The validated overall classification accuracies
VCA) were 61.7% for the freshness, 79.2% for the packaging 80.5% for the season
and 61.7% for the day of purchase. The shelf life of beef fillets and minced beef was
evaluated and correlated with FTIR spectral data. This analysis revealed
discrimination of the samples regarding their freshness (VCA 81.6% for the fillets,
76.34% for the mince), their storage temperature (VCA 55.3% and 88.1% for the
fillets and mince, respectively) and the packaging type (VCA 92.5% for the mince).
Moreover, estimations of the different microbial populations using Partial Least
Squares Regression (PLS-R) were demonstrated (e.g. Total viable counts-TVC:
RMSE 1.34 for the beef fillets and 0.72 for the mince). Cont/d.