Crush berries with a masher or a food processor (pulse if using a food processor) leaving chunks of fruit.

Measure crushed fruit into a large bowl. Stir in lemon juice. Gradually stir in pectin, mix thoroughly and set aside for 30 minutes, stirring every 5 minutes or so to dissolve pectin.

Stir in corn syrup (this prevents sugar crystallization during freezer storage). Gradually add sugar, stirring until sugar is completely dissolved.

Pour into clean plastic or glass containers with lids leaving ½ inch space at the top for expansion. Cover and let stand at room temperature for 24 hrs.

Refrigerate up to 3 weeks or store in the freezer for up to 1 year. Thaw in refrigerator before using.