Although it’s always best to use fresh berries when possible, wonderful jam can easily be made from frozen strawberries as well. Defrosting the strawberries beforehand will speed the process along. You can use them straight from the freezer, but it will take a little longer to reach jam stage.
Things You'll Need
Place strawberries, lemon juice, sugar and pectin in the pot. For every quart of frozen berries, use 1/8th cup of lemon juice and about 4 cups of sugar. Stir together; if berries are frozen, you may have to wait until they defrost.
Turn burner up to the highest level of heat that it can reach. Continue stirring.
Watch your jam as the strawberries start to turn to mush and the mixture begins to come together. Add the pectin. Use the amount recommended on the package for the amount of berries you’ve cooked. Stir occasionally; stirring continuously is not necessary. Make sure you stay close enough to your pot to observe.
Bring jam to a rolling boil and cook for one full minute. Add a pat or two of butter and stir into jam. Turn the heat off.
Funnel jam into prepared home canning jars and can in your usual manner.
It is possible to make strawberry jam without pectin. In fact, that’s probably how your great-grandmother used to make it before pectin was commercially available. A pectin-free process involves reducing a lot of the natural juice out of the strawberries, which may reduce their nutritional value. If you wish to try making strawberry jam without pectin, omit all ingredients except the strawberries and the sugar. Use about 50 percent more sugar and boil until the jam starts to thicken. Ladle into your prepared home canning jars as above. Pectin-free jam may be runnier than jam with pectin.
It is also possible to make strawberry jam without added sugar, for those with dietary concerns. Alternative sweeteners such as stevia or sucralose replace the sugar. Consult product packaging to determine the proper amount for your recipe.
References and ResourcesBall Blue Book Guide to Preserving (100th Anniversary Edition), Hearthmark, 2009
How to Make Jam Without Added Sugar