Preservation of fresh meat with active and modified atmosphere packaging conditions.

The sensory, microbiological and physicochemical attributes of fresh meat stored at 5 and 15 degrees C were affected by the combined effect of volatile compounds of oregano essential oil and modified atmosphere packaging conditions (40% CO2/30% N2/30% O2, 100% CO2, 80% CO2/20% air, vacuum pack and air). It was found that the extension of shelf life of meat samples depended on the packaging conditions and augmented in the order: air < vacuum pack < 40% CO2/30% N2/30% O2 < 80% CO2/ 20% air < 100% CO2. Longer shelf life was observed in samples supplemented with the volatile compounds of oregano essential oil and stored under the same packaging conditions mentioned above. The extension of shelf life may be due to the synergistic effect of volatile compounds of oregano essential oil and the modified atmosphere packaging used on the microbiological and physicochemical characteristics of meat. Indeed, both these hurdles can prolong and delay microbial growth or suppress the final counts of the spoilage microorganisms in comparison with the 'control' samples. The effect of essential oil volatile compounds was even more pronounced on the physicochemical changes of meat samples caused by microbial association. Oregano essential oil delayed glucose and lactate consumption, both indicators of meat spoilage aerobically as well as under 40% CO2/30% N2/30% O2, and 100% CO2. Finally, changes in other metabolites such as formic acid were also observed.