Some fruit arrives hard and softens on a kitchen counter, while other fruit never improves after picking. The division is biological and it determines how the entire supply chain for each is built.
Two kinds of ripening
Climacteric fruits, including bananas, avocados, tomatoes and pears, continue to ripen after being detached from the plant.
Non-climacteric fruits such as grapes, citrus and berries do not, and whatever sweetness and texture they have at harvest is what they will have when eaten.
That single difference explains why some produce is shipped hard and green while other produce must be picked ready and moved quickly.
A plant hormone drives the process
Climacteric fruits produce ethylene, a gaseous hormone that triggers softening, colour change and the conversion of starch to sugar.
Production accelerates once it begins, so the fruit effectively signals to itself and ripening runs to completion without any further input from the plant.
Because the gas moves through the air, one ripening fruit hastens others nearby, which is the mechanism behind the familiar advice about storing bananas separately.
Harvesting early buys transport time
Ripe fruit is soft, bruises easily and has a very short window before it is unsaleable.
Picking a climacteric fruit while firm makes it robust enough to survive handling and a long journey, and ripening is then completed at the destination.
Controlled rooms manage temperature and atmosphere to hold the fruit dormant, and a measured dose of ethylene starts the process on a schedule set by demand.
Flavour and ripeness are not the same
Softening and colour respond to ethylene, but sugars and aromatic compounds accumulate through the plant while the fruit is still attached.
Fruit picked very early therefore reaches the shop looking ripe while carrying less of the flavour it would have developed on the tree.
This is the underlying reason a tomato bought in winter can look correct and taste thin, and why locally grown produce in season tastes noticeably different.
The split shapes what is available
Non-climacteric produce has to be grown close to its market or moved by fast, expensive routes, which limits where and when it can be sold.
Climacteric produce can be sourced from anywhere with a suitable climate and timed to arrive continuously, which is why some fruit has no season in the shops at all.
Availability across the year is therefore less a matter of farming technology than of which category a given fruit falls into.