Controlled Atmosphere Storage for Apples and Pears
Have you ever wondered why you can continue to enjoy domestic apples and pears long after they are harvested in October/November? Growers extend the life of their fruit by keeping them in cold storage, effectively slowing down the natural ageing and ripening process. As time goes on the sugar, starch and acid content changes, water is lost and the fruit withers and decays.
Apples and pears are divided into either fresh or controlled atmosphere (CA) storage. Most fruit through the end of the year is taken from fresh storage where fruit is put into a chilled cellar or cooler and kept between 32 and 36 degrees F with high air humidity and some air circulation. A good comparison is your refrigerator at home. When the fresh storage runs out apples and pears will then be pulled from CA storage.
Only the best quality fruit is chosen for long term CA storage. The fruit is stored in airtight coolers where they remain in a state of “sleeping” until the rooms are opened up at a predesignated time. CA is a non-chemical process where the oxygen level is reduced to about 1-2% by infusing nitrogen gas to slow down the maturation process to a near halt. Think of sleeping beauty under a spell and how she never aged a day until she woke up.
Temperatures are kept at a consistent 32–36 degrees F with 95 percent humidity. The exact conditions of each room vary by apple and pear variety, allowing many varieties to be stored into the winter, spring and even summer months. The storage life of apples in CA can last up to 12months and up to 10 months for pears depending on the variety. The higher the starch in the fruit, the longer it can be stored.
When the apples and pears are brought out of hibernation for packing they will begin to ripen and break down quickly as starches turn to sugar again. It is best to enjoy them right away and keep them in your refrigerator until eaten. Once the CA storage of apples and pears run out, the supplies are augmented by apples and pears from the southern hemisphere until the season starts up again in the fall.