Michigan State University Extension
Preserving Food Safely - 01600553
Freezer jam is often called uncooked jam. As noted by at least one manufacturer of pectin, a few sugar crystals will remain in freezer jams. Nothing can be done about this.
If freezer jam is too firm, stir to soften. If it tends to separate, stir to blend. If it is too soft, bring it to a boil. It will thicken on cooling. Store uncooked jams in the refrigerator or freezer. They can be held for up to four weeks in a refrigerator or up to a year in a freezer. If kept at room temperature, they will mold or ferment in a short time. Once a container is opened, jam should be stored in the refrigerator.
Freezer jams can be made with powdered or liquid pectin. Check commercial packages for the recipes.