Does Fruit Ripen After It's Cut?

Ethylene and Ripening

• A fruit often begins as a flower or blossom, and after fertilization, it grows through many stages until it reaches maturity. Ripening begins only after a fruit matures, and during that time, it changes color and texture and develops its characteristic taste. The substance that triggers the ripening process is ethylene; its molecular structure includes two carbon and four hydrogen atoms. When ethylene reaches a critical concentration in a fruit, typically from 1/10th to 1 part per 1 million, the fruit's ripening process begins. Once that process begins, it is irreversible.

Amount by Variety

• The characteristic of a fruit that determines whether or not it must stay attached to the plant to ripen is the amount of ethylene it produces. Fruits that produce relatively small amounts of ethylene include berries, citrus fruits, grapes, pomegranates and cherries. They must ripen on the tree. Pears, peaches, bananas, avocados and many other fruits, on the other hand, produce larger amounts of ethylene and continue to ripen after they are picked. Producers often pick them before they are ripe because they are firm then, which makes them better able to withstand processing and transportation.

Acceleration of Ripening

• Externally applying ethylene can accelerate the ripening process of fruits that already produce large quantities of the hormone ethylene, but it doesn't have much effect on those that produce little ethylene. In the latter fruits, ripening is much more connected to the maturation process, and cutting them off from the plant curtails that process. The method of externally applying ethylene can be as simple as preventing dispersal of the ripening agent in the air. That's why you can make pears, peaches, bananas and many other fruits ripen faster by putting them in bags.

Refrigerator or No Refrigerator

• Even though fruits low in ethylene don't ripen after they are picked, some rot more quickly than others and should be put in a refrigerator as soon as possible. Those fruits include most berries as well as figs and lychees. It's fine to leave citrus fruits, watermelon, pomegranates and kumquats at room temperature if you wish. They won't ripen, but they deteriorate more slowly than some other fruits. Fruits that continue to ripen should stay out of a refrigerator until they have a suitable color and texture. Prematurely refrigerating them makes them lose their flavor and turn mealy.