Effect of varying oxygen concentrations on the shelf-life of fresh pork sausages packaged in modified atmosphere

A total of 105 fresh pork sausages were packaged in atmospheres varying in oxygen concentration, using the following mixtures (%O2/%CO2/%N2): 0/20/80, 0/20/80 + O2 scavenger, 20/20/60, 40/20/40, 60/20/20, and 80/20/0. In addition, two batches were subjected to vacuum packaging or over-wrap with O2-permeable film. They were stored for 20 days at 2 ± 1 °C in the dark. Values of pH, CIE L*, a* and b* color parameters, surface metmyoglobin percentage, TBA-reactive substances, psychrotroph aerobe bacterial numbers and sensory discoloration and off-odor were assessed throughout storage. Packaging in the absence of O2, either under vacuum or in atmosphere with O2 scavenger, led to extension of shelf-life in terms of both color and odor stability due to low oxidation rates. Increase of O2 caused a significant enhancement of oxidation, decrease of shelf-life due to discoloration and off-odor development. The highest O2 concentration gave rise to a significant color improvement, though only for a limited period of 8 days.