Dry food, as flour, potato chips, peanuts, coffee, spices, and also dried milk and cacao products contain more or less unsaturated fats.
These products are susceptible for oxidation and going rancid. Even very small amounts of oxygen may deteriorate the quality of this type and make them completely unsuitable for sale. For that reason, protective atmosphere of an inert gas (e.g. nitrogen) is used very often by packaging of these products.
Carbon dioxide slows down the growth of mould at bread.
The main reasons for bakery product deterioration are the growth of mould and chemical decomposition. Fermentation may cause problems at stuffed bakery products. As the water activity in the bakery products is low, the growth of other germs than that of mould only rarely cause a problem.
The mould growth is an aerobic process that may be effectively forestalled by its destruction by carbon dioxide; its application considerably extends the product shelf life by many days. Packaging in the protective atmosphere is particularly suitable for rye bread, sweet bakery products, and different fruit cakes and pies.