A controlled atmosphere is an agricultural storage method. An atmosphere in which oxygen, carbon dioxide and nitrogen concentrations are regulated, as well as temperature and humidity. Two major classes of commodity can be stored in controlled atmosphere. 1. Dry commodities such as grains, legumes and oilseed. In these commodities the primary aim of the atmosphere is usually to control insect pests. Most insects cannot exist indefinitely without oxygen or in conditions of raised (greater than approximately 30% carbon dioxide). Controlled atmosphere treatments of grains can be a fairly slow process taking up to several weeks at lower temperatures (less than 15°C). A typical schedule for complete disinfestation of dry grain (<13% moisture content) at about 25°C, with carbon dioxide, is a concentration above 35%(v/v) carbon dioxide (in air) for at least 15 days. 2. Fresh fruits, most commonly apples and pears, where the combination of altered atmospheric conditions and reduced temperature allow prolonged storage with only a slow loss of quality.
