Michigan State University Extension
Preserving Food Safely - 01600335
Whole The syrup pack is preferred for berries to be satisfactory for cooking. Select full-flavored, ripe berries all about the same size, preferably with tender skins. Sort, wash and drain.
Use one of the following packs: Syrup pack. Pack berries into containers and cover with cold 50-percent syrup (1 cup sugar to 1 cup water). Seal, label and freeze.
Unsweetened pack Pack berries into containers. Seal, label and freeze.
Crushed or puree Select fully ripened berries. Sort, wash, and drain. Crush, or press berries through a fine sieve for puree. To 1 quart (2 pounds) crushed berries or puree, add 2/3 cup sugar, depending on tartness of fruit. Stir until sugar is dissolved. Pack into containers. Seal, label and freeze.