Tree-ripened apple freshness in the middle of Canadian winter

February 10, 2015

Most people associate apple season with the fall – cool crisp days when apples are harvested fresh from the tree. However, fresh and juicy Ontario apples are available right through the winter months too.

That’s thanks to modern science and technology that lets farmers and apple packers carefully store apples so we can enjoy them after the fall harvest season too.

Apples stored in a commercial refrigerated storage will keep for two to three months, but for long term storage up to 12 months, apple growers use controlled atmosphere (CA) storage.

Here’s how it works:

Apples breathe or respire just like people. They naturally take in oxygen and generate carbon dioxide, water and heat through a process called respiration. CA storage is a completely natural process that reduces respiration to a minimum by controlling the environment in which the fruit is stored.

Apples for CA storage are picked at their peak of internal quality and condition. They are rushed into a CA storage chamber the day they are picked. Once the temperature in the chamber is reduced to 1C, the room is sealed with an airtight door and the oxygen level inside is lowered from a normal level of 21 per cent down to two or three per cent.  This stops the ripening process by essentially putting the apples to sleep (similar to hibernation in animals) until they are ready to go to market. 

Special equipment is used to monitor and control oxygen and carbon dioxide levels inside the sealed storage area to make sure the apples maintain their quality. The quicker apples are cooled and placed into the desired atmosphere, the longer they will store and be of good quality upon removal.

CA storage does not improve fruit quality so if poor quality apples go into storage, they will still be of poor quality when they come out. How long apples can stay in storage depends on the variety; each has specific characteristics.

A few of the largest growers have on-farm CA storage, and may offer storage services to other growers. Most growers store their apples off-farm; storage facilities may be part of a packing business, a privately owned storage company, or a grower co-op.

CA storage has been used in the Ontario apple industry for more than 50 years. Over 40 per cent of apples grown in the province are stored using controlled atmosphere storage. Although apples are a popular fruit during the fall harvest season, a large number of Ontario apples are sold and consumed during the winter months. Typically, fresh Ontario apples will be available until May or even early June.

Story by Lilian Schaer for Ontario Apple Growers