Front face fluorescence spectroscopy and multi-way data analysis for characterization of milk pasteurized using instant infusion

Front face fluorescence spectroscopy was applied for characterization of milk pasteurized using instant infusion at six different temperatures, ranging from 72 °C to 120 °C. Comparisons were made with raw milk and milk subjected to high temperature short time (HTST) pasteurization at 72 °C for 15 s as well as with a more intensive pasteurization at 85 °C/30 s. Fluorescence excitation emission matrices (EEMs) were measured covering excitations from 250 nm to 350 nm and emissions in the range from 260 nm to 500 nm. The different heat treatments were separated based on three components by parallel factor analysis (PARAFAC) of the EEMs. Two components were suggested to be related to protein and one component to be vitamin A. Different models were needed for skim milk and non-standardized milk. Front face fluorescence spectroscopy, which requires no sample preparation, in combination with PARAFAC appears to be a powerful tool for discrimination of different milk heat treatments.