Controlled atmosphere
Encyclopedia
A controlled atmosphere is an agricultural
storage method. An atmosphere in which oxygen
, carbon dioxide
and nitrogen
concentrations as well as temperature
and humidity
are regulated.
Two major classes of commodity can be stored in controlled atmosphere:
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...
storage method. An atmosphere in which oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
, carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
and nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
concentrations as well as temperature
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
and humidity
Humidity
Humidity is a term for the amount of water vapor in the air, and can refer to any one of several measurements of humidity. Formally, humid air is not "moist air" but a mixture of water vapor and other constituents of air, and humidity is defined in terms of the water content of this mixture,...
are regulated.
Two major classes of commodity can be stored in controlled atmosphere:
- Dry commodities such as grainsCerealCereals are grasses cultivated for the edible components of their grain , composed of the endosperm, germ, and bran...
, 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. These atmospheres can be created either by:- adding pure gases carbon dioxide or nitrogen or the low oxygen exhaust of hydrocarbon combustion, or
- using the natural effects of respiration (grain, moulds or insects) to reduce oxygen and increase carbon dioxide Hermetic storage.
- 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.
See also
- Modified atmosphereModified atmosphereModified atmosphere is the practice of modifying the composition of the internal atmosphere of a package in order to improve the shelf life....
- Modified atmosphere/modified humidity packagingModified atmosphere/modified humidity packagingModified atmosphere/modified humidity packaging is a technology used to preserve the quality of fresh produce so that it can be sold to markets far away from where it is grown, extend the marketing period, and to help suppliers reduce food waste within the cold chain...
- Shelf lifeShelf lifeShelf life is the length of time that food, drink, medicine, chemicals, and many other perishable items are given before they are considered unsuitable for sale, use, or consumption...
- Cold chainCold chainA cold chain is a temperature-controlled supply chain. An unbroken cold chain is an uninterrupted series of storage and distribution activities which maintain a given temperature range...