Packaging gas

Packets of drysnack foods,such as this packet ofWotsits,commonly usenitrogenas a packaging gas to keep the contents from going stale or damp prior to being opened.

Apackaging gasis used to pack sensitive materials such asfoodinto amodified atmosphereenvironment. Thegasused is usuallyinert,or of a nature that protects the integrity of the packaged goods, inhibiting unwanted chemical reactions such as foodspoilageoroxidation.Some may also serve as a propellant foraerosol sprayslike cans ofwhipped cream.For packaging food, the use of various gases is approved by regulatory organisations.

TheirE numbersare included in the following lists in parentheses.

Inert gases

These gas types do not cause a chemical change to the substance that they protect.

• argon(E938), used for canned products
• helium(E939), used for canned products
• nitrogen(E941), also propellant
• carbon dioxide(E290), also propellant

Propellant gases

Specific kinds of packaging gases areaerosol propellants.These process and assist the ejection of the product from its container.

• chlorofluorocarbonsknown as CFC (E940 and E945), now rarely used because of the damage that they do to theozone layer:
  • dichlorodifluoromethane(E940)
  • chloropentafluoroethane(E945)
• nitrous oxide(E942), used for aerosol whipped cream canisters (seeNitrous oxide: Aerosol propellant)
• octafluorocyclobutane(E946)

Reactive gases

These must be used with caution as they may have adverse effects when exposed to certain chemicals. They will cause oxidisation or contamination to certain types of materials.

• oxygen(E948), used e.g. for packaging of vegetables
• hydrogen(E949)

Volatile gases

Hydrocarbongases approved for use with food need to be used with extreme caution as they are highly combustible, when combined with oxygen they burn very rapidly and may cause explosions in confined spaces. Special precautions must be taken when transporting these gases.

• butane(E943a)
• isobutane(E943b)
• propane(E944)

See also

• Shielding gas