Packaging under a protective atmosphere keeps food hygienically perfect and durable for longer without preservatives or thermal preservation. This protects against premature spoilage and thus the loss of food.
Worldwide, consumer demand for fresh products from the refrigerated shelf is increasing. These are offered refrigerated and without thermal preservation or preservatives. In the sensitive convenience sector, hygiene and shelf life as well as gentle processing and packaging solutions therefore play a particularly important role.
A very effective method of making food storable over a longer period of time is packaging under a protective atmosphere, also known as MAP (Modified Atmosphere Packaging). The air in the packaging is replaced by a gas mixture suitable for the product. The latter can significantly slow down the oxidative decomposition process or the growth of microbes and moulds. The inert gas also reduces the breathability of the products, so that they retain their freshness, taste and appetising appearance much longer.
Decisive parameters for packaging in a protective gas atmosphere are the gas mixture adapted to the product and the use of packaging materials with appropriate passive barrier properties against oxygen, carbon dioxide and water vapour.
The basic requirements for effective MAP packaging are modern packaging machines such as flow wrapping machines, tray sealing machines, thermoforming machines, vacuum chamber machines or bag sealing machines as well as gas mixers and regulators, gas analysers and tubes for introducing the gas into the packaging.
When packaging under a protective gas atmosphere, the gas tightness of the protective gas packaging is particularly important. Defective seals resulting from the slightest leakage may result in a loss of aroma and flavor or even premature spoilage of the goods. Gas tightness measurements for quality control are therefore a must at MAP. Depending on the requirements, random sample measurements are carried out in the laboratory or test chambers are integrated into the packaging lines for inline process control.
What can be packaged under protective gas?
The field of application is large and ranges, for example, from packaged fresh meat, sausage and cold cuts to cheese, pre-baked rolls; bread and baked goods for baking, pasteurized food such as pasta or ready meals, sliced fruit products, nuts, but also sandwiches. The German Federal Office for Risk Assessment (BfR) estimates that in Germany about 90 percent of pre-packaged fresh meat in the self-service area of food stores is packaged in a protective gas atmosphere.
The shelf life of sandwiches increases from 2 - 5 days packed under air to 7 - 10 days under MAP, for ready meals from 2 - 3 days packed under air to 7 - 20 days, for sausages it increases from 2 - 4 days under air to 2 - 5 weeks under MAP.
Technical gases for the packaging of foodstuffs
Technical gases are extracted from the air using various methods. When used in the food industry, they fulfil different tasks depending on the gas used. The main inert gases used are carbon dioxide (CO2), nitrogen (N2) and oxygen (O2), occasionally also argon (Ar).
Carbon dioxide prevents the packaged products from oxidizing. It also inhibits the reproduction of bacteria and fungi, but does not kill existing germs. The higher the CO2 content in the packaging, the longer the shelf life of the products.
Nitrogen, with a share of 78 percent, is the main component of the air we breathe. The gas is inert and has a high purity due to its extraction. It is used to displace the oxygen in the air. It thus prevents oxidation of the food and inhibits the growth of aerobic microorganisms.
Although oxygen is responsible for the oxidative spoilage of food, in certain cases it is deliberately used to prevent colour fading and inhibit the growth of anaerobic microorganisms, for example in red meat. Oxygen also serves as a respiratory reserve in so-called fresh-cut products.
Argon has similar properties to nitrogen and is intended to prevent certain enzymatic browning reactions of the packaged products.
The inert gases used in the packaging of foodstuffs must be in accordance with
EU Regulation 95/2/EC with their corresponding E-number must be indicated on the label.