Ethylene, Ripening & Other Questions

Answers for all your Frequently Asked Questions about Ethylene and the Ripening process can be found below. Please feel free to contact us should you have any further questions or concerns.

Ethylene Questions: 
The Ethylene Facts & FAQ’s page

Ripening tips for many fruits:
Our Ripening Tips page

Our Banana Color Chart & Ripening Guide (with temperature / scheduling)
“Suggested Guide for Banana Ripening”

“Flow Through Ventilation:” Designed to continuously vent Carbon Dioxide from the ripening room and introduce fresh air, resulting in more uniform ripening.
“Suggested Flow-Through Diagram and Fan size calculation”

I sometimes feel light-headed or find it difficult to breath in a ripening room during the initial stages of the ripening cycle. What causes this?
For the first few days of a ripening cycle, fruit takes in a large amount of oxygen and produces carbon dioxide. This CO2 must be vented from the room. Lack of ventilation can make it difficult to breathe. Venting of the ripening room replaces CO2 with fresh oxygen not only makes it easier for people to breathe in the room but also gives the fruit the fresh air it needs to properly ripen. CO2 inhibits the ripening process and, when not vented out, can cause uneven and delayed ripening, and, while not very likely, but possibly a difficult breathing environment.

Many ripening rooms are vented manually, by opening the room door for several minutes every 12 hours. Some rooms have automatic ventilation, either timed or controlled by a CO2 detector.

I hear that ethylene is explosive. How can I be sure that I’m safe from this danger?
Yes, ethylene is very explosive. At concentrations above 27,000 part per million (ppm), just a spark can cause it to explode. There have been several instances of explosions in ripening rooms where cylinders were in use…we have compiled a list of ethylene explosions.

However, the ripening process of most fruits can be initiated by ethylene at concentrations as low as 50 ppm, or less than 1% of the explosive level, and most operators ripen with 1,000 ppm or less. Catalytic Generators are the safest commercial form of ripening; they produce small, controlled amounts of ethylene and when used as directed, they cannot produce explosive amounts of ethylene. That is why so many fresh produce companies use our generators rather than gas cylinders.

When using our generator and Ethy-Gen® II Ripening Concentrate in rooms that are 43 m3 or larger, there is NO CHANCE OF ETHYLENE EXPLOSION. The United Kingdom takes the threat of explosion from cylinders very seriously. The UK’s Health and Safety Executive/Local Authorities Enforcement Liaison Committee (HELA) has posted a circular on their web site explaining that generators are the preferred options for ethylene application and that the “use of cylinders of pure ethylene should be vigorously discouraged.” For more details, please click here.

Is ethylene really necessary for banana ripening?  Won’t they ripen on their own?
Bananas are harvested mature but very green in order to survive the trip from the growing regions to destinations across United Kingdom.  Along with a rise in pulp temperature, an external ethylene application will trigger the proper ripening process to begin, which includes the fruit producing internal ethylene. This natural process results in uniform, controlled and predictable ripening.  Without this exposure to external ethylene, bananas will eventually soften, but the change in color will not be uniform and the peel will be dull, pale yellow, and unattractive.

My bananas are not ripening evenly. What can be causing this?
Uneven ripening is caused by one of at least four things:

  1. Insufficient amount of ethylene, caused any of these situations:
    • Generator setting too low for room size
    • Not applying ethylene long enough to trigger the fruit to ripen on its own
    • An air leak, large enough to considerably reduce ethylene levels, has developed somewhere in the ripening room
  2. Immature fruit: When harvested, the fruit had not yet reached a mature stage. In order for fruit to ripen properly, it must be picked when fully developed and mature
  3. Mixed lots: a room of fruit that contains various grades, comes from different origins, or is not uniform in characteristics will usually not ripen evenly
  4. Old fruit: When ripening fruit that has been “held” for an extended period of time after harvest, the ripening results will inevitably vary and will usually involve uneven ripening, as some of the fruit will begin to ripen before others. As a general rule with most types of fruit, it is best to apply ethylene as soon as possible to mature green fruit; this ensures that all fruit within the room will ripen even and uniformly.

Why does Catalytic Generators make sure that their generators comply with UL® and TÜV Product Service Standards?
These are independent, private organizations formed to help reduce injury, loss of life, and property damage. Their scientists investigate and test products to evaluate their electric, fire, and casualty hazards. We felt that, since our generators are electrical instruments, it would be in the best interest of our customers to ensure that our equipment is of top quality and workmanship; passing these stringent safety standards would be the best test. With these marks on our generators, our customers can rest on the fact that the equipment has been found to be reasonably free from foreseeable risk of fire, electric shock, and related hazards. You can see their web sites here:

What is the shelf life of Ethy-Gen® II Ripening Concentrate?
5 years. The product should be tightly sealed and stored in a dry, out-of-traffic area at temperatures of less than 51°C, and in accordance with local fire codes and state/federal safety regulations.