Apples sold in spring were picked the previous autumn. They survive that gap in storage that manipulates the atmosphere around them, not merely the temperature.
Fruit keeps respiring after harvest
A picked fruit remains biologically active, consuming oxygen and its own stored sugars while producing carbon dioxide, heat and water vapour.
That respiration consumes the very qualities the fruit is stored for, so the rate of respiration effectively sets how long it can be kept.
Cooling slows the process substantially, which is why refrigeration extends life at all, but cooling alone reaches a limit well short of a full season.
Reducing oxygen slows it further
Controlled atmosphere stores lower the oxygen concentration well below that of ordinary air and raise carbon dioxide, which suppresses respiration far more than chilling alone.
The fruit is effectively held in a state of very slow metabolism, and on removal it resumes ripening broadly from where it stopped.
The margins are narrow. Too little oxygen and the fruit switches to fermentation, producing off flavours and internal damage, so the atmosphere is monitored continuously.
Ripening hormones are managed separately
Many fruits produce a gaseous hormone that triggers ripening in themselves and in nearby fruit, and its accumulation in a sealed store would defeat the whole arrangement.
Stores therefore scrub the gas from the atmosphere, and some operations apply a compound that blocks the fruit's ability to respond to it.
The same chemistry works in reverse for fruit shipped unripe. Applying the hormone in a ripening room brings a consignment to condition on a controlled schedule before distribution.
Not every fruit tolerates cold
Tropical and subtropical fruits suffer chilling injury below a threshold that is well above freezing, showing pitting, failure to ripen and off flavours.
This is why bananas, mangoes and tomatoes are stored and shipped warmer than apples, and why refrigerating them at home produces disappointing results.
The threshold differs by species and even by variety, so storage regimes are specific rather than general and are developed for each commodity.
Texture is where long storage shows
Long-stored fruit generally retains sugar and acidity better than it retains firmness, because cell walls soften through processes that cold slows but does not halt.
Varieties are selected and bred partly for storage performance, which is one reason the range in shops differs from what grows well in gardens.
Consumers reading a fruit as old are usually responding to texture rather than to flavour, and the storage system is designed around exactly that perception.