Application of nitrogen (N2) and carbon dioxide (CO2) in MAP

Almost all food deterioration and spoilage are directly or indirectly related to the presence of oxygen in the air. At the same time, food and air contact, but also dry consumption phenomenon. Dry depletion will not only reduce the weight of food, but will inevitably be accompanied by a decline in quality, such as flavor reduction, surface atrophy, color change.

The principle of food vacuum packaging, MAP packaging and other forms of packaging is based on trying to isolate food from oxygen so as to effectively prevent the oxidation of nutrients such as fat and the growth and reproduction of microorganisms in food, so as to achieve the purpose of extending the storage time of food. The so-called vacuum packaging, is the bag of air pumped out, a vacuum state. Less oxygen in the bag, inhibit the reproduction of bacteria, extend shelf life, and can pack large food. However, these methods are easy to deform food. In recent years, MAP developed and became popular. After putting food into a film bag with good air tightness, the mouth is sealed, the air in the bag is pumped out, and then inert gas is filled, so that the food is isolated from the oxygen in the air, so as to prevent the oxidation and deterioration of food and the reproduction of microorganisms. The effect of MAP is better than that of vacuum packaging. MAP is an ideal new packaging method.

The most commonly used MAP gases are nitrogen (N2), carbon dioxide (CO2), and oxygen (O2) or a mixture of them. Nitrogen is stable and is used to remove oxygen, thus slowing down the oxidation and respiration of food. Nitrogen also has a certain inhibition effect on the growth of bacteria. In addition, nitrogen is basically insoluble in water and oil. The adsorption effect of nitrogen on food is very small, and the phenomenon of gradual shrinkage will not occur due to the absorption of gas during packaging.

Carbon dioxide is one of the key gases in MAP. It can inhibit the growth of bacteria and fungi. When used for fruit and vegetable packaging, carbon dioxide has the effect of strengthening and reducing oxygen and breathing intensity. However, when using carbon dioxide, we must pay attention to the high solubility of carbon dioxide to water and oil, and the formation of carbonic acid after dissolution will change the pH value and taste of food. At the same time, after the dissolution of carbon dioxide, the amount of gas in the packaging will be reduced, which can easily lead to the shrinkage of food packaging, not full, and affect the appearance of food. The use of carbon dioxide in MAP must take into account many factors such as storage temperature, moisture content of food, type and quantity of microorganisms, etc.

MAP generally uses oxygen only in the following three situations

1. Oxygen is used to maintain the color of food, such as meat.
2. Maintain the respiration of fruits and vegetables.
3. Inhibits the growth of anaerobic microorganisms.