Processed meats

Packaging, protection from external conditions

Poisson frais

In processed meats such as cured meats or ham, there is a loss of colour over time if they are not protected from external conditions during storage.

Oxygen can have an effect on pigmentation when the product is exposed to light, producing a grey-brown colour that is not conducive to storing processed meats in good conditions. In processed meats, the desired oxygen level is often less than 1%, or even 0.2% on slices of ham for example, as pork is a very sensitive product.


Tightness will be measured by the rate of increase in oxygen content as a function of the leakage rate or the size of the equivalent defect in µm. The stricter the acceptance criteria, the longer the shelf life. In France, legislation stipulates a maximum shelf life of 3 months.

In addition, the manufacturer must take into account the mode of transport and the effects of pressure variations on the packaging. The acceptance criterion for the permissible leakage rate must also take into account the breathability of the packaging and the exchange rate of the headspace, depending on the conditions of use. A pack with a small headspace exposes the product more, with a faster rate of internal volume renewal.

Conversely, in the case of fresh meat, often presented in transparent packaging, oxygen enrichment enables the meat to be coloured but considerably reduces its shelf life, from 2 to 4 days on the retailer’s shelf. On the other hand, the manufacturer can choose to inject large quantities of CO2 to guarantee asepsis, which has the disadvantage of giving the meat a burgundy colour but increasing its shelf life by a few weeks, generally between two and five.

For aesthetic reasons, CO2 packaging can be wrapped in opaque film to mask the undesirable visual aspect.


Processed meat can also be broken down by bacteria. These bacteria are generally different from those found in raw meat, as they are generally introduced during processing stages such as drying or marinating. Moulds are sometimes sought in this process, particularly for dry sausages.

Gas mixtures for modified atmosphere packaging also take account of this particular microbial spoilage profile, which dictates the necessary proportions of carbon dioxide and nitrogen.