Inside a SCS Controlled Atmosphere room for apples

A controlled atmosphere is an

agricultural Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled peopl ...

storage method in which the concentrations of

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements ...

carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is t ...

and

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...

, as well as the

temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied o ...

and

humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present. Humidity dep ...

of a storage room are regulated. Both dry commodities and fresh fruit and vegetables can be stored in controlled atmospheres.

Dry commodities

Grains,

legumes A legume () is a plant in the family Fabaceae (or Leguminosae), or the fruit or seed of such a plant. When used as a dry grain, the seed is also called a pulse. Legumes are grown agriculturally, primarily for human consumption, for livestock for ...

and

oilseed Vegetable oils, or vegetable fats, are oils extracted from seeds or from other parts of fruits. Like animal fats, vegetable fats are ''mixtures'' of triglycerides. Soybean oil, grape seed oil, and cocoa butter are examples of seed oils, or f ...

are stored in a controlled atmosphere primarily to control insect pests. Most insects cannot survive indefinitely without oxygen or in conditions of raised (>30%) carbon dioxide. Such controlled atmosphere treatments of grains may take several weeks at lower temperatures (<15 °C). A typical schedule for complete disinfestation of dry grain (<13% moisture content) with carbon dioxide at approximately 25 °C 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 carbon dioxide or nitrogen, or the low oxygen exhausts of hydrocarbon combustion, or * using the natural effects of respiration (by grain, molds or insects) to reduce oxygen and increase carbon dioxide ( Hermetic storage).

Fruit and vegetables

The method is most commonly used on

apples An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple trees are cultivated worldwide and are the most widely grown species in the genus ''Malus''. The tree originated in Central Asia, where its wild ancestor, ' ...

and pears, where the combination of altered atmospheric conditions and reduced temperature allow prolonged storage with only a slow loss of quality. The long-term storage of vegetables and fruit involves inhibiting the ripening and ageing processes, thus retaining flavor and quality. Ripening is delayed by reducing the level of oxygen and increasing that of carbon dioxide and nitrogen in the cool cell so that the respiration is reduced. Normal atmosphere consists of approximately 78% nitrogen, 21% oxygen, 0.3% carbon dioxide and smaller amounts of some other gasses. In controlled atmosphere the oxygen is reduced to 1.5–2% by replacing it with nitrogen and a little bit of carbon dioxide, which is produced by fruits. Under controlled atmosphere conditions the quality and the freshness of fruit and vegetables are retained, and many products can be stored for 2 to 4 times longer than usual.

History

Franklin Kidd and Cyril West of

Cambridge University , mottoeng = Literal: From here, light and sacred draughts. Non literal: From this place, we gain enlightenment and precious knowledge. , established = , other_name = The Chancellor, Masters and Schola ...

did the basic research into fruit respiration and ripening leading to the first commercial facility in 1929. By 1960, there was capacity for 4 million bushels of apples in the US and by the 1980s, capacity exceeded 100 million bushels. The technique of CA was improved by Robert Smock, a professor at

Cornell University Cornell University is a private statutory land-grant research university based in Ithaca, New York. It is a member of the Ivy League. Founded in 1865 by Ezra Cornell and Andrew Dickson White, Cornell was founded with the intention to tea ...

. He visited Cambridge in the late 1930s to observe the work of Kidd and West. Smock in his research was trying to figure out how to extend the shelf life of different fruits such as apples and pears. When he returned to New York he adapted CA to work for local apple varieties, focusing on how to make McIntosh's apples last longer. In his laboratory in a barn near the university, he made different experiments by placing apples in sealed rooms at different temperatures and with various mixtures of oxygen and carbon dioxide to see how the fruit would respond. As a result of Smock's work, the first CA rooms in the U.S. were built in New York in the 1950s, causing the apple consumption season to extend to springtime nationwide.

References

{{DEFAULTSORT:Controlled Atmosphere Agriculture Atmosphere de:Controlled Atmosphere

Dry commodities

Fruit and vegetables

History

See also

References