It now favours gentler techniques that protect the inherent quality of the food and leave the product unchanged. These range from high-pressure and microwave processes, to packaging techniques such as oxygen absorption, vacuum, sous-vide techniques and modified atmosphere packaging (MAP).
MAP is a natural, shelf-life-enhancing method. Rapidly growing in popularity around the world, MAP often complements other methods. The correct MAP gas mixture maintains quality, by retaining a foodstuff’s 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 high moisture content, MAP inhibits the growth of microorganisms. For products with a high fat content and low water activity, oxidation protection is the primary objective.
MAP gas mixtures usually consist of normal atmospheric gases: carbon dioxide, nitrogen and oxygen. Microorganism growth can also be inhibited with the help of other gases, such as nitrous oxide, argon and hydrogen. Each of these has its own unique properties that affect its interaction with foodstuffs. The gases can be applied individually, or mixed in specific ratios.
The impressive results of carbon dioxide
Carbon dioxide is the most important gas in MAP technology. It strongly affects most microorganisms (such as mold and the most common aerobic bacteria).
Carbon dioxide has a more limited impact on the growth of anaerobic microorganisms. It inhibits microbial activity by effectively dissolving into the food’s liquid and fat phase, reducing its pH value. It also penetrates biological membranes, causing changes in permeability and function.
Nitrogen – inert and stabilizing
Nitrogen is an inert gas. It is primarily used to prevent oxidation, by replacing oxygen in packaging. 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 foods, the package should contain as little oxygen as possible. This delays the growth of aerobic microorganisms and reduces oxidation. However, there are some exceptions. Oxygen helps to preserve the oxygenated form of myoglobin, which gives meat its red color. It is also required for food and vegetable respiration.
