The Ripening of Bananas & Fruit

Green bananas quickly ripen when placed with ripe fruit.

Like many fruits, bananas are usually harvested when mature, before they ripen. They are then ripened at the market. Once ripened the fruit needs to be used quickly. Commercial growers make a science out of holding and ripening fruit, but for home purposes, bananas and most other fruit ripen at room temperature very successfully. Ripening is caused by the presence of ethylene gas produced by ripe fruit or artificially produced to ripen fruit for market.

Ripening Bananas on the Tree

Bananas formed on the plant can often take months to fill out to a mature size for picking. It is normal for fruit to form on the plant in the fall, then fill out and ripen in the spring. Bananas are ready for picking when they are a mature size but still green. Bananas ripened on the tree spoil very quickly. They often split open, ruining the banana. Bananas ripened on the tree tend to be too soft for hand eating.

Storing and Ripening Bananas and Fruit Off the Tree

Fruits are picked when mature, before they ripen, to increase storage and shipping qualities. Store bananas at 56 to 58 degrees, raising the temperature to 59 to 68 degrees to ripen. Bananas and other fruit ripen in a few days at room temperature. Speed up the process by placing them near other ripe fruit.

Cold Injury Prevents Ripening

Like many other fruits, bananas subjected to temperatures below 56 degrees Fahrenheit before ripening are subject to chilling injury. The surface of the peel turns dark brown or black and make the banana more susceptible to bruising. Chilled bananas do not ripen properly and eventually the banana also darkens. Some other fruit, such as peaches, plums and nectarines, undergo similar cold injury that prevents ripening. Store unripe fruit at room temperature.

Stages of Banana Ripening

Bananas in the "turning" stage are pale yellow, but still have some green. Bananas are good for cooking at this stage.

Once the peel turns yellow the banana is considered "hard ripe." The fruit is still firm, but the starch has been converted to fruit sugar and the banana is sweet.

"Fully ripe" fruit is deep yellow with brown flecks. The peel will turn completely brown over time. At this point, the fruit is sweet and soft. When fully ripe, bananas spoil quickly. Use them immediately or freeze for future use.

References

• University of California Postharvest Technology Research and Information Center; Banana; Adel A. Kader; January 2009
• Washington State University; Ethylene--The Ripening Hormone; Sylvia Blankenship; March 2000
• UCLA Mildred E Mathias Botanical Garden; Hands with Yellow Fingers
• University of Florida Cooperative Extension; Banana; Anne Cooper, et al.; March 1995
• University of California Postharvest Biology and Technolory; Susceptibility to Chilling Injury of Peach, Nectarine and Plum Cultivars; Carlos H. Crisosto, et al.; October 1999