The avocado is a climacteric fruit, which means the fruit will not ripen while they are still hanging on the tree. So no matter when the farmer harvests their fruit, the avocados will be rock hard. If harvested at the correct stage, the fruits will ripen and become soft, but at uneven rates under normal conditions.
They need to ensure their avocados remain hard enough to transport without injury and then soften them just in time for the consumers.
This brings up 2 issues that producers need to consider: how can they keep the fruit from ripening too quickly and how can they initiate ripening at the perfect time?
The first problem is commonly solved using a combination of 2 treatments: controlled atmosphere storage and SmartFresh™ applications.
CA storage helps to prolong the shelf-life of the avocados by preventing ripening. The fruit therefore will remain harder for longer and thus be more resistant to disease and injury. CA storage achieves this by regulating the ratio of oxygen and carbon dioxide gases in the storage room, in addition to maintaining ambient temperatures of 5°C. The general rule is that higher carbon dioxide and lower oxygen levels will retard ripening. There have been some reports of storing unripe avocados for up to 9 weeks and longer using Controlled Atmosphere storage.
This is a commercial product that contains the active compound 1-methylcyclopropene, or 1-MCP. This compound blocks the production of ethylene by binding to receptors in the fruit when SmartFresh™ is sprayed onto the avocados. Ethylene is a gaseous hormone that initiates ripening of fruit. So, by limiting the amount of ethylene produced by the fruit, the shelf life will be prolonged.
But what happens when the fruit need to be ripened just in time to head to the grocery stores or markets? Firstly, storage temperatures and humidity levels must be increased to around 25°C at 90% humidity for a couple of days. The fruit can also be exposed to higher doses of ethylene, the ripening hormone. You can do this yourself at home by storing unripe avocados in brown bags with a couple of bananas. Bananas produce large amounts of ethylene which can be used to soften your avocados.
And there you have it, some of the ways that commercial avocado producers store and treat their avocados to maintain shelf life and trigger ripening at the perfect times.