An average of 12 pounds makes a 7-quart canner load. An average of 7½ pounds is needed per canner load of 9 pints. An average of 1 pound makes 1 pint of frozen berries.
Select berries that are plump, firm, have a light blue to blue-black color, and are of ideal maturity for eating fresh. Refrigerate for 1 to 2 days to improve flavor, then preserve them.
Just before preparing, wash 1 or 2 quarts at a time and drain well. Do not soak berries.
Don't freeze more than 2 pounds of food per cubic foot of freezer capacity per day. Berries may be packed with syrup or dry sugar, pureed, or individually quick frozen.
To Make a Syrup Pack
Mix and dissolve 2½ cups of sugar in 4 cups of water. Add 1 cup of this syrup per quart of prepared fruit. To keep berries under the syrup, place a small piece of crumpled water-resistant paper or wrapping material on top, and press fruit down into the syrup before sealing the container.
To Make a Dry Sugar Pack
Mix 1/2 cup of dry sugar per quart of prepared fruit.
Crushed or Pureed Berries
To make crushed or pureed berries, crush or press washed berries through a fine sieve, or puree in a blender or food processor. Mix 1 to 1⅛ cups of sugar with each quart (2 pounds) of crushed berries or puree. Stir until sugar is dissolved.
Fill pint or quart plastic freezer containers or tapered widemouth freezer jars. Allow 1 inch of headspace in quarts and ½ inch in pints. Seal, label, and freeze. Do not freeze in containers with a capacity over one-half gallon.
Individually Quick Frozen or Tray Method of Freezing Blueberries
Berries may be frozen without washing, then washed just before being used. Another option is to wash and dry berries thoroughly on a clean towel before freezing. Spread dry berries in a single layer on a flat tray and place in freezer. Once hard, transfer to a freezer container or zip-type freezer bag. Do not thaw before use.
Note: Select berries that are plump, firm, have a light blue to blue-black color, and are of ideal maturity for eating fresh.
Wash jars. Prepare lids according to manufacturer’s instructions. Berries in jars may be covered with your choice of water, apple or white grape juice, or, more commonly, a very light, light, or medium syrup. To make a very light syrup for a canner load of quarts, mix 1¼ cups of sugar in 10½ cups of water and heat to dissolve; mix and dissolve 2¼ cups of sugar in 9 cups of water to make a light syrup; or mix 3¾ cups of sugar in 8¼ cups of water to make a medium syrup. Hot or raw pack as directed below. Wipe sealing edge of jars with a clean, damp paper towel. Add lids, tighten screw bands, and process jars.
To Make a Hot Pack
Place drained berries in boiling syrup, juice, or water and boil for 30 seconds. Fill clean jars with hot berries and cooking liquid, leaving ½ inch of headspace.
To Make a Raw Pack
Place drained berries in jars and cover with your choice of boiling syrup, juice, or water, leaving ½ inch of headspace.
To Process in Boiling Water Canner
Fill canner halfway with water and preheat to 180°F for hot packs or 140°F for raw packs. Load sealed jars into the canner rack and lower with handles, or load one jar at a time with a jar lifter onto rack in canner. Add water, if needed, to 1 inch above jars. Add cover. When water boils vigorously, lower heat to maintain a gentle boil and process for recommended time. After processing is complete, set canner off heat and remove canner lid. Wait 5 minutes before removing jars. Remove jars from canner with a jar lifter and place on a towel or rack. Do not retighten screw bands. Air-cool jars for 12 to 24 hours. Remove screw bands and check lid seals. If the center of the lid is indented, wash, dry, label, and store jar in a clean, dark place. If lid is unsealed, examine and replace jar if defective, use new lid, and reprocess as before. Wash screw bands and store separately. Berries are best if consumed within a year and are safe as long as lid remains vacuum sealed.
To Process in an Atmospheric Steam Canner
Preheat the base of a steam canner that has been filled with the amount of water designated in the instruction manual that comes with the canner—usually about 2 quarts. Set the rack in the base of the canner. Heat water in the base of the canner to 180°F. As each jar is filled, place it on the canner rack, keeping the cover or lid on the atmospheric steam canner as you work. When all jars are in the canner, bring the canner to a boil over medium to medium-high heat until a steady column of steam at least 6 inches long escapes from the vent hole(s). Processing time begins when there is a column of steam 6 to 8 inches long. Slowly adjust the heat to maintain a steady column of steam throughout the processing time. When processing is complete, remove the canner lid or cover. Allow the jars to sit in the canner for 5 minutes before removing them from the canner with a jar lifter to a towel-covered counter. Do not retighten screw bands. Cool, inspect, label, and store jars as described above in boiling water canner instructions.
Table 1. Recommended process times for raw or hot pack in a boiling water or atmospheric steam canner at designated altitudes.
|Style of pack||Jar size||Process time (in minutes)|
at 0–1,000 ft
|Process time (in minutes) |
at 1,001–6,000 ft
|Process time (in minutes) above 6,000 ft|
|Hot||Pints or quarts||15||20||25|
|Syrup||Half-pints or pints||10||15||20|
- 2 1/2 cups prepared blueberry juice
- 3 cups sugar
- 1/2 cup corn syrup
- 2 Tbsp. lemon juice
Yields approx. 4 half-pint jars
To Prepare Juice:
Select 4 cups of table-ripe berries. Do not use underripe berries. Wash berries and remove any stems. Crush berries and heat to a boil. Simmer for 1 or 2 minutes. Strain through a colander and drain until cool enough to handle. Strain the collected juice through a double layer of cheesecloth or jelly bag. Discard dry pulp. The yield of the juice should be about 2½ cups.
To Make the Syrup:
Combine ingredients in a saucepan. Bring to a rolling boil and boil for 1 minute. Remove from heat and skim off foam. Pour into hot half-pint jars, leaving ¼ inch of headspace. Wipe jar rims and adjust lids. Process for 10 minutes in a boiling water bath or atmospheric steam canner.
Source: Andress, Elizabeth L., and Judy A. Harrison. So Easy to Preserve. 6th ed. (Athens: University of Georgia Cooperative Extension Service, 2014).
For additional information about food preservation, visit the Penn State Extension Home Food Preservation website or contact Penn State Extension in your county.