There were high losses in storage in bygone years - if grain was not dry enough, it could be spoiled by mildew or fungus, there were high losses to mice and birds, apples could only be stored for a few months, potatoes and other roots could be stored under heaps of earth for 6 months, cabbage could be pickled, jams could be made, hams and fish could be smoked or salted, and people could get through the winter until the first green shoots of spring arrived, perhaps tightening their belts a little to get by.
Later, foods could be canned, bottled, or dried.
Nowadays, it is a different story. Even if there were no imports, one can find local apples, onions and potatoes everywhere that have been stored for 9 months before being sold, still looking perfect.
How is this done ? I think there are 3 main possibilities
- Now that air-conditioning equipment is easily available, some crops can be kept for a long time at constant temperatures in cool rooms, just above freezing, especially with good aeration (apples or potatoes would be spoiled by freezing)
- Many products are deep-frozen, either raw or after initial cooking.
- A process of irradiation has also been introduced, where the product is exposed to radiations from radioactive isotopes. This results in products which are biologically dead, but which look fine.
With imports as well, we can now buy Brussels Sprouts in April and strawberries at Christmas !!