The science of ripening: Why some fruits need more time on the vine

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

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

Climacteric fruits and vegetables can ripen after being picked. These include 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 causes them to ripen faster.

Ethylene also activates various processes, leading to softening, pigment production, aromas, and sugar production. Therefore, the more mature a climacteric fruit is, the softer and sweeter it becomes. Although ethylene production can be slowed down, it still leads to fruit ripening after harvest. Additionally, climacteric fruits can accelerate the ripening process of other fruits nearby.

Non-climacteric fruits are a specific group that 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, they cannot produce autocatalytic ethylene. In their tissues, the concentration of this gas remains at a constant, low level. In practice, this means that the ripening process of these fruits occurs exclusively on trees or bushes. After being picked and cut off from the gas production source, these fruits stop producing it and, consequently, stop ripening. Therefore, when it comes to strawberries or sweet cherries, they should be picked and bought when they are ripe, as they will not become softer or sweeter over time.