Shelf life of rabbit hamburgers ageing in vacuum or modified atmosphere packaging

Consumers demand high quality meat products with natural flavour and taste. The high quality and safety of fresh meat products are important features to be conserved during the storage and distribution. An approach to overcoming the short shelf-life problem of meat products is to use vacuum or modified atmosphere packaging. Rabbit hamburguers were made from loin and thigh meat; chilled hamburgers (0°C±1; 5°C±1), packed with vacuum (Multivax) or modified atmosphere (30%CO2-70%N2) were analysed at 1, 7, 14, 21 and 28 days after preparation (6 hamburgers/portion/packet/temperature/day). Lipid oxidation (Tbar’s index), raw colour (CIELAB system, Minolta Chroma Meter-CR300) and pH (Testo 205) were determined. Fatty acids were analysed as methyl esters by gas chromatography. Cooking losses were determined by weight difference (grill, 71ºC±1ºC). Raw burgers were also analysed by an analytical panel of 8 trained assessors for overall colour, odour intensity and off-odours. Statistical analysis was performed using the Proc Mixed of SAS (2004) for repeated measurements. Differences between treatments were analysed by Tukey test (p<0.05). Vacuum and MAT packaging had similar effects on burgers quality until 28 days of storage. The longer time and higher temperature of conservation increased relative values of the colourimetric parameters, exudation and intensity of odour. Up to 28 days of storage, both lipid oxidation and the intensity of off-odour perception was very low. After 21 days, saturated and monounsaturated fatty acids and trombogenic index showed higher values while there was a lower content of polyunsaturated fatty acids. In conclusion, vacuum and MAT atmosphere packaging showed similar effects on the qualitative traits analysed which were influenced by the origin of meat, temperature of conservation and storage time.