Microbial growth and oxidation of the red oxymyoglobin pigment are the main spoilage mechanisms that limit the shelf life of raw red meats. The packaging technologist has to maintain the desirable red colour of the oxymyoglobin pigment, by having an appropriate O2 concentration in the pack atmosphere, and at the same time minimise the growth of aerobic microorganisms. Highly pigmented red meats, such as venison and wild boar, require higher concentrations of O2.
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Aerobic spoilage bacteria, such as Pseudomonas species, normally constitute the major flora on red meats.
Since these bacteria are inhibited by CO2, it is possible to achieve both red colour stability and microbial inhibition by using
gas mixtures containing 20–30% CO2 and 70–80% O2. These mixtures can extend the chilled shelf life of red meats from 2–4 days to 5–8 days. A gas/ product ratio of 2:1 is recommended.
Red meats provide an ideal medium for the growth of a wide range of spoilage and food poisoning microorganisms including E. coli. Because raw red meats are cooked before consumption, the risk of food poisoning can be greatly reduced by proper cooking. The maintenance of recommended chilled temperatures and good hygiene and handling practices throughout the butchery, MAP distribution and retailing chain is of critical importance in ensuring both the safety and extended shelf life of red meat products.