About Ethylene Gas

What is ethylene gas?

Ethylene gas (C₂H₂) is an odorless, colorless gas that exists in nature and is also created by man-made sources.  Not easily detectable, it exists where produce is stored. In nature, the largest producers are plant and plant products (i.e., fruits, vegetables and floral products) which produce ethylene within their tissues and release it into the surrounding atmosphere.  It is also a by-product of man-made processes such as combustion (propane forklifts, smog).

How was the role of ethylene discovered?

The role of ethylene and its effect on produce was discovered by accident.  Lemon growers would store newly harvested green lemons in sheds kept warm by kerosene heaters until they turned yellow and ripened enough to market.  When new modern heating systems were tried, the lemons no longer turned yellow on time.  Research soon found that the important factor in the ripening process was small amounts of ethylene gas given off by the burning kerosene in the heaters.

The natural role of ethylene gas.

Ethylene, also known as the “death” or “ripening hormone” plays a regulatory role in many processes of plant growth, development and eventually death.  Fruits, vegetables and flowers contain receptors which serve as bonding sites to absorb free atmospheric ethylene molecules.  The common practice of placing a tomato, avocado or banana in a paper bag to hasten ripening is an example of the action of ethylene on produce.  Increased levels of ethylene contained within the bag, released by the produce itself, serves as a stimulant after reabsorption to initiate the production of more ethylene.  The overall effect is to hasten ripening, aging and eventually spoilage.  A refrigerator acts in much the same way. Kept closed to retain the desired temperature, it also enables an increased concentration of ethylene to accumulate.  Any closed environment, such as a truck trailer, ocean shipping container or warehouse will have a similar effect.

Why control ethylene?

Storage of produce items is of economic importance to the food and floral industry.  Storage allows producers, handlers and sellers to spread availability over periods of strong and weak demand, maintaining supply and stabilizing cost. Within the industry, it is estimated that losses directly related to ethylene run into the billions of dollars annually.  Removal of ethylene from the storage and shipping environment retards spoilage, reduces loss and increases profit.