Freezing fruits: Blueberries, blackberries and other fruits are prime for harvest this time of year. If you have certain fruits you enjoy and want to keep them to enjoy throughout the year, you might want to consider freezing them.

There are five factors that are involved in successful freezing, according to the Penn State Cooperative Extension. Those factors are:

Enzymes: Enzymes control the ripening process in fruits, and freezing only slows that process. In order to control enzyme activity, it is a good idea to add ascorbic acid, or Vitamin C, to fruits that are headed for the freezer. Dissolve ½ teaspoon of ascorbic acid in 3 tablespoons of cold water and sprinkle over four cups of fruit before adding sugar or use ½ teaspoon of powdered or crushed ascorbic acid to each quart of cold syrup.

Air: It is important to avoid exposure to air, as air leads to browning, particularly with lighter colored fruits. Adding ascorbic acid can be helpful with this issue as well as the enzyme factor noted above.

Microorganisms: Freezing does not kill microorganisms, it merely slows their growth. Given the fact that microorganisms are present in all fresh fruit, it is important to make sure that fruit is frozen at 0 degrees Fahrenheit or below. Once the fruits are thawed, it is important to handle and prepare them with care to avoid issues with bacteria or mold.

Large ice crystals: Freezing fruit quickly is the ideal way to preserve it, as this causes small ice crystals and preserves the texture of the fruit.

Try to keep only two pounds of frozen food per square foot of freezer space, in order to allow air to circulate and freeze the fruit quickly and keep the temperature of frozen food as low as possible.

Evaporation of moisture: In addition to allowing space for air to circulate, it is important to utilize the proper freezer packaging to avoid exposure to oxygen and allow for moisture loss. Remove as much air as possible before closing the packaging, and fill excess headspace with crushed plastic wrap.

In a future RTS, we will discuss headspace and tips for successful fruit freezing.