Atmospheric Controls

What products can I use to control the atmosphere around my organic produce?

By Taryn Kennedy

Atmospheric control is an important factor in the preservation of produce that is used during shipping and storage to delay ripening, extend shelf life, or prevent decay. Atmospheric composition is crucial to fruits and vegetables, because they “breathe” or respire as they mature, consuming oxygen (O2) and producing carbon dioxide (CO2) and a hormone called ethylene. Ethylene induces ripening, causing the produce to soften and shorten its shelf life. In the enclosed space of an unventilated container, produce can quickly change the atmosphere, altering the normal levels of O2 and CO2. Adjusting the balance of these gases or reducing the amount of ethylene in the container can thwart the effects of post-harvest pathogens, decay, or insect infestation.

There are a number of viable approaches to modifying the atmosphere of shipping or storage containers, including the addition of inert gases, ethylene absorbents and filters, or breathable packaging materials. A modified atmosphere is one that is created by altering the normal composition of air (78% nitrogen [N2], 21% oxygen [O2], 0.03% carbon dioxide [CO2] and trace gases) to provide an optimum atmosphere for increasing the storage length and quality of produce.

Inert atmospheric gases such as N2, O2, or CO2 can be added to containers to replace the content of a particular gas. Ethylene absorbents or filters can be used to remove ethylene gas to extend the shelf life of the harvested crop. Absorbents are typically composed of a mineral such as zeolite or vermiculite that is impregnated with potassium permanganate. These can be sold in bulk as pellets or marketed in packets or sachets. Gas-selective or breathable packaging liners and containers control gas exchange between the produce and the atmosphere. OMRI evaluates ethylene absorbing sachets as packaging materials. You can read more about those standards here: https://www.omri.org/packaging-materials.

Since organic produce must maintain its organic integrity from the field to the consumer, storage and packing operations must meet organic standards. Gases that are added to control the atmosphere around organic products, and absorbents that are added into packaging are considered food contact substances. If the product is not separated by packaging (e.g. ethylene sachets) and contacts the food directly, the substance must appear at 7 CFR 205.605 or §205.606 to be allowed for use in organic production. At §205.605, oil-free grades of O2 and N2 are allowed nonsynthetics and CO2 is an allowed synthetic. While ethylene is an allowed synthetic for the use of post-harvest ripening of fruit, ethylene absorbents are not allowed to have direct contact with food (unless composed of materials appearing on the National List).

OMRI will review input products that come into contact with organic food (e.g. inert gases), ethylene sachets, or permeable packaging materials. Devices and technologies, however, are considered out of scope. For this reason, ethylene devices that control atmospheric gas concentrations or filter out ethylene in a processing or storage facility are not within the scope of the OMRI Review Program.

This article was originally published in the fall 2013 edition of the OMRI Materials Review newsletter, and was revised in June 2025 by Research and Education Manager Peter O. Bungum and Technical Research Analyst Colleen Al-Samarrie. 

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