Periodically ozone has been promoted as a supplement to refrigeration in the storage of apples and certain other commodities for possible control of spoilage. Ozone has not been found beneficial, however, in the storage of apples. For example, continuous use of 3.25 parts per million of ozone failed to prevent decay of apples stored at 31° to 32°F, and caused injury. The time of appearance and the extent of injury differed with the variety. Rome Beauty, Arkansas, Delicious, York Imperial, Winesap, and Golden Delicious varieties were tested. Golden Delicious was the most susceptible, but all were injured to some degree.
Typical injury occurs at the lenticels. Cells immediately surrounding the lenticels are killed, and the tissues collapse, turn brown, and form small pits. The injury on Rome Beauty resembles one phase of Jonathan spot on that variety. If a large enough sample of affected fruits were observed, however, Jonathan spot would probably also occur as superficial brown areas without definite margins.
The Rome Beauty apple illustrated was injured in 30 days in 3.25 ppm of ozone.
A shiny, sticky, varnish-like cuticle was found on ozonized Arkansas and Winesap varieties after about 5 months' storage. The other varieties did not develop this characteristic.
Ozone injury, Rome Beauty