PREDICTIVE MODELING OF THE FRESHNESS OF MINCED BEEF MEAT STORED IN MAP AT DIFFERENT TEMPERATURES

The aims of this work were: 1) to follow the freshness decay of packaged minced beef meat stored at different temperatures (4.3, 8.1 and 15.5 degrees C) by applying both traditional methods (microbiological counts, TBA assay, headspace gas composition) and non-invasive methods (e-nose and color measurement); 2) to model the kinetics in order to obtain information about the maximum acceptability time as function of storage conditions. The minced beef, packaged with high gas barrier materials in MA was directly supplied by a manufacturer at the beginning of its commercial life and analysed at different times according to the storage temperature. Shelf life study revealed the ability of the traditional methods in describing the kinetic of freshness decay. The classical modeling of the experimental data and the comparison with microbiological or chemical thresholds allowed the setting, for each index, of a stability time exceeding which the meat was no longer acceptable. The quality decay of meat was also evaluated by inspecting the headspace fingerprint of the same set of samples by means of a commercial e-nose. A clear discrimination between "fresh", "old" and "very old" samples was obtained by using PCA and CA, determining at each temperature a specific range of stability time. Colour attributes were evaluated by using conventional colorimeter. All the stability times estimated for each index allowed the building of a generalized time-temperature tolerance chart, obtaining also a Q10 mean value. The results show that the Q10 values from the traditional methods (3.6-3.8 range) were accordingly overlapped with the Q10 estimated through e-nose and colour indexes (3.4 and 3.3 respectively).