Canning and Freezing Blueberries

Selection Guidelines

• Select plump, firm blueberries with a light silvery bloom. 
• Blueberries need to be fully ripe; unripe berries (ones that are white or green) do not become sweeter after they are picked. Berries that have turned purple, red, or blueish usually do ripen after they are picked if they are kept at room temperature. Ripe blueberries have a light blue to blue-black color. Red or green berries have a sour flavor. 
• Big berries have a sweeter flavor. That doesn't necessarily mean the flavor is better, as part of the appeal of any berry is its tartness.

Preparation—Treat Blueberries Gently

• Blueberries are delicate.
• Examine the berries carefully and remove squashed, diseased, or moldy berries.
• Do not wash fresh blueberries until you are ready to use them. They will spoil quickly if they are refrigerated while wet. 

Freezing Blueberries

Refer to Penn State Extension's Let's Preserve Blueberries for directions on freezing blueberries without sugar, with dry sugar, or in syrup. There are even directions for freezing pureed blueberries.

• Because moisture on the surface of a frozen berry toughens the skin, some sources recommend freezing blueberries without washing and then washing them before being used. 
• Another option is to wash the berries before freezing, but then thoroughly dry them. Lay them out in a single layer on a towel and blot dry.
• To freeze blueberries, spread dry berries on a flat tray and place in the freezer. Once hard, transfer the frozen berries to any closed container or freezer bag. Do not thaw when you are ready to use them.
• It is best to freeze only the amount that will be used within one year. Properly frozen berries will be safe to use for longer periods of time, but signs of quality deterioration such as freezer burn and textural changes will begin to show.

Canning Blueberries

• Blueberries may be canned in light or medium sugar syrup or may be covered with water, apple juice, or white grape juice.
• Blueberries may be packed into jars raw or may be heated in syrup before packing. Heating the berries removes air from the berries and reduces floating fruit and siphoning (loss of liquid from the jar).
• Process the blueberries in a boiling water or atmospheric steam canner. Check process times in recipe.
• Make altitude adjustments if you live at an altitude above 1,000 feet.
• Review the Let's Preserve: Basics of Home Canning before you start.

Don't Overlook the Spreads

Use blueberries to make life sweet. Try some of the following recipes.

• Blueberry-Spice Jam
• Spiced Blueberry-Peach Jam  
• Blueberry Syrup
• The recipe inserts in boxes of commercial pectin include more recipes using blueberries.

Use in Prepared Foods

• Prepare pies, muffins, and other quickbreads made with fresh, canned, or frozen blueberries.
• Freeze the prepared food for use at a later date. Wrap in air-tight freezer bags or in vapor-proof containers.

Did You Know?

• Blueberries are one of only a few fruits native to North America. 
• They are readily available in June and July.
• July is National Blueberry Month in the United States.
• Blueberry muffins are the most popular muffin in the United States.

References

LaBorde, L.; Zepp, M.; & Hirneisen, A. (2023, April 13). "Let's Preserve: Blueberries". Penn State Extension.

LaBorde, L.; Zepp, M.; & Hirneisen, A. (2023, March 1). "Let's Preserve: Basics of Home Canning". Penn State Extension.

LaBorde, L.; Zepp, M.; & Hirneisen, A. (2023, August 3). "Let's Preserve: Jelly, Jam, Spreads". Penn State Extension.

National Center for Home Food Preservation. (2024). Blueberry-Peach Jam (Spiced) without pectin. University of Georgia.