Eating crisp, juicy Washington apples year-round is possible due to controlled atmosphere storage. CA storage got its start in England before World War II when farmers discovered their produce kept longer if stored in an airtight room. It was up to scientists to unravel the reasons for longer storage.
Apples take in oxygen and give off carbon dioxide as starches in the flesh change to sugar.
In the sealed rooms, this respiratory process reduced the oxygen, thus slowing the ripening process. CA storage has come a long way since then, and researchers in Washington state have been among the leaders in this technology. CA was first used in the United States in the 1960s and Washington now has the largest capacity of CA storage of any growing region in the world. The large, airtight CA rooms vary in size from 10,000 boxes to 100,000 boxes, depending on the volume of apples produced by the apple shipper and his marketing strategies. CA storage is a non-chemical process.