Packaging Gases
Packaging gases are generally used to change the atmosphere inside a food package to decrease the growth rate of microorganisms and to extend the shelf-life of the product. The most common gases used are carbon dioxide and nitrogen.
Carbon dioxide (E290)
Carbon dioxide (E290) makes up approximately 0.1% of the air that we breathe and is a colourless, odourless and non-flammable gas which is soluble in water. It is prepared as a by-product of of ammonia or hydrogen production and when solid it is known as ‘dry ice’. Carbon dioxide can be used for the carbonation of beverages in brewing and soft drinks industries and as a modified-atmosphere packaging gas. As a packaging gas it has a powerful inhibitory effect on the growth of bacteria, being especially effective against Gram-negative spoilage bacteria such as Pseudomonas sp. Carbon dioxide acts by forming a mild carbonic acid on the surface of the food, lowering the pH and producing an environment hostile to bacteria. It can also inhibit mould growth. Its use in packaging extends the life of products in both quality and food-safety and can be used on its own or with other packaging gases. As carbon dioxide is denser than air and is an asphyxiant at concentrations in air above 7%, care must be taken when working with the gas in enclosed spaces. It is permitted quantum satis in the EU.
Argon (E938)
Argon (E938) is extracted from air which contains approximately 0.9% argon and is used to replace air within food packages to extend shelf-life by removing the oxygen which supports chemical and microbiological activity. In the modified atmosphere system argon may be used as an alternative to nitrogen as it is denser and less is required. It is relatively rarely used however as it is much higher in cost. As it is denser than air, the safety of workers using argon needs to be considered. In the EU it is permitted quantum satis.
Helium (E939)
Helium (E939) is mostly obtained from natural gas wells and can be used in modified atmosphere food packaging. While not as effective as nitrogen in preventing spoilage, helium can still displace oxygen and create an inert to slow down oxidation and microbial growth in some packaged foods. It is however rarely used as it is expensive and small molecular size making it easily leak. It is permitted in the EU quantum satis.
Nitrogen (E941)
Nitrogen (E941) is the major constituent of air (78.1%) and prepare pure nitrogen air is filtered, dried, compressed and cooled and it can be provided as a liquid or a gas. It is used in food packaging to replace air and also in whipping foams, creams and mousses. It is also used for food freezing and chilling. Using nitrogen in packaging means that oxygen cannot cause spoilage and deterioration and it also inhibits the growth of microorganisms that require oxygen to grow. Nitrogen is often used alongside carbon dioxide. It has quantum satis status in the EU.
Nitrous oxide (E942)
Nitrous oxide (E942) is most commonly obtained by the thermal decomposition of ammonium nitrate and is used in dairy products to both provide foaming and to extend shelf-life. Nitrous oxide is permitted as a packaging gas but is mostly used in foamed dairy products such as ready to serve whipped cream where it also provides inhibition of oxidative rancidity. It is permitted in the EU quantum satis.
Oxygen (E948)
Oxygen (E948) comprises 20.9% air from which it is extracted by a process of filtration, drying, compression, liquefaction and fractional distillation. It is commercially available as a gas or liquid. Whilst most packaging gases are used to exclude oxygen there are some cases where it can be beneficial. A high oxygen content preserves the redness of meat and so can be used 20:80 with carbon dioxide. It is also used in a low oxygen/high nitrogen environment to reduce the respiration rate and extend the shelf-life of prepared salads (95% nitrogen: 5% oxygen). Oxygen is used in fish packaging as complete removal of oxygen may permit the growth of pathogenic anaerobic organisms such as Clostridium botulinum. It is permitted quantum satis in the EU.
Hydrogen (E949)
Hydrogen (E949) is produced from natural gas or other hydrocarbon fuels or electrolytic decomposition of alkalised water. Its principle use in the food industry is in the processing of fats and oils where used with a catalyst it converts double bonds in unsaturated oils to single bonds creating stable saturated fats. It has also been considered an innovative component of gas mixtures for atmosphere packaging applications. It is permitted quantum satis in the EU.
