CA storage is a non-chemical process. Oxygen levels in the sealed rooms are reduced, usually by the infusion of nitrogen gas, from the approximate 21 percent in the air we breathe to 1 percent or 2 percent. Temperatures are kept at a constant 32 to 36 degrees Fahrenheit. Humidity is maintained at 95 percent and carbon dioxide levels are also controlled. Exact conditions in the rooms are set according to the apple variety.
Researchers develop specific regimens for each variety to achieve the best quality.
Computers help keep conditions constant. Timing of harvest is critical to good storage results. Apples picked too early will not store well in CA nor will those that are past the proper maturity. In mid-August, apple growers start testing the maturity of their apples to accurately predict when to harvest their crop to put in CA rooms so the apples are mature, but not too ripe. Firmness, skin color, seed color, sugar level and flesh chlorophyll are tested.