Understanding ripening: How to identify climacteric and non‑climacteric fruits

Like avocados or tomatoes, a green banana will ripen while lying on the kitchen counter. However, this is not true for all fruits and vegetables. Some can only reach maturity on the tree or bush; if picked too early, they will not develop full color or flavor.

Climacteric fruits are a specific group that can ripen both while growing on the tree or bush and after being picked. However, it is essential to note that not all fruits and vegetables exhibit this property. Some should only be picked or harvested when fully mature.

Climacteric fruits and vegetables can ripen after being picked. This group includes apples, pears, bananas, kiwis, mangoes, avocados, papayas, watermelons, plums, nectarines, peaches, tomatoes, and broccoli. These fruits produce ethylene, a natural gas that stimulates cellular respiration and accelerates ripening.

Ethylene also activates nutrients, causing softening, pigment production, aroma enhancement, and sugar production. Therefore, the more mature a climacteric fruit is, the softer and sweeter it becomes. While ethylene production can be slowed down, it still leads to fruit ripening after harvest. Additionally, climacteric fruits can speed up the ripening process of other nearby fruits.

Non-climacteric fruits cannot ripen after being picked from the tree or bush. This group includes cherries, sweet cherries, strawberries, raspberries, blackberries, lemons, oranges, pineapples, grapes, peppers, and olives.

Unlike climacteric fruits, non-climacteric fruits do not produce autocatalytic ethylene. The concentration of this gas in their tissues remains constant and low. In practice, this means that the ripening process of these fruits occurs exclusively on the tree or bush. Once picked and cut off from the gas production source, these fruits stop producing ethylene and, consequently, stop ripening. Therefore, fruits like strawberries or sweet cherries should be picked and purchased at their peak ripeness, as they will not soften or sweeten over time.