Packaging with protective gas is mainly used for pre-baked goods and confectionery baked goods such as plain cakes. The technology called modified atmosphere packaging (MAP) describes the exchange of the normal gas composition (ambient air) in the packaging with special gases. Predominantly carbon dioxide, nitrogen or a mixture of both are used.
Necessary are special packaging machines and gas-tight packaging materials.
Mould fungi are aerobic micro-organisms, they require oxygen to grow. The oxygen content of the ambient air is approx. 21 %. To restrain the growth of the mould, the oxygen content in the packaging has to be lowered to below 0.5 %.
Carbon dioxide is microbicide (killing of micro-organisms) and thus provides good mould protection. The carbon dioxide is partly converted into carbonic acid, whereby the products can become slightly sour. This can also involve a collapsing of the packaging. For this reason, nitrogen (N2) is used as a supporting gas in addition. As a rule, gas mixtures of 40 – 80 % CO2 and 20 – 60 % N2 are used. The ratio depends on the baked goods which have to be wrapped, as well as on the gas permeability of the packaging material.