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The food industry is moving away from preservative methods that physically or chemically alter foodstuffs in favour of gentler techniques that protect the inherent quality of the food and leave the product unchanged. These alternative approaches range from high-pressure and microwave processes, to packaging techniques such as oxygen absorption, vacuum, sous-vide techniques and MAP.
MAP is a natural, shelf life enhancing method that is rapidly growing in popularity on an international scale. It often compliments other methods. The correct MAP gas mixture maintains the quality of the foodstuff by retaining the original taste, texture and appearance.
The gas atmosphere must be carefully adapted to the individual foodstuff and its properties. In the case of low fat products with a high moisture content, MAP focuses on inhibiting the growth of microorganisms in particular. However, in the case of products with a high fat content and low water activity, oxidation protection is the primary objective.
MAP gas mixtures usually consist of the normal atmospheric gases such as carbon dioxide (CO2), nitrogen (N2) and oxygen (O2). Microorganism growth can also be inhibited to a certain extent with the help of other gases such as nitrous oxide (N2O) , argon (Ar) and hydrogen (H2). Each of the gases has its own unique properties that affect its interaction with the foodstuffs. The gases can be applied individually or mixed according to specific ratios.
Extending high quality shelf life by inhibiting microbal deterioration
Impressive results with carbon dioxide
Carbon dioxide is the most important gas in the field of MAP technology. Most microorganisms (such as mould and other common aerobic bacteria) are strongly affected by carbon dioxide.
Carbon dioxide has a more limited impact on the growth of anaerobic microorganisms. carbon dioxide inhibits microbial activity by effectively dissolving into the food’s liquid and fat phase, thereby reducing its pH value. It also penetrates biological membranes, causing changes in permeability and function.
Nitrogen - inert and stabilising
Nitrogen is an inert gas. It is primarily used to replace oxygen in packaging, thereby preventing oxidation. Owing to its low solubility in water, nitrogen also helps to prevent package collapse by maintaining internal volume.
Oxygen level should be as low as possible
For most foodstuffs, the package should contain as little oxygen as possible to slow the growth of aerobic microorganisms and reduce the degree of oxidation. However, there are some exceptions. Oxygen helps to preserve the oxygenated form of myoglobin, which gives meat its red color. Oxygen is also required for food and vegetable respiration.