Freezing Raspberries & Blackberries
Select well-colored berries that are fully ripe. Avoid leaky, mushy, or discolored fruit.
Before freezing, remove any berries that are immature, moldy or discolored.
To wash berries, place in a colander and submerge two or three times in a sink full of cold water. Drain well.
Dry Freezing (unsweetened):Use this if you want separately frozen berries (rather than a solid block). This method works best if you do NOT wash the berries. If you do wash them, be sure they drain well; consider placing them on an absorbent terry cloth towel and patting very gently before freezing.
Place the fruit in a single layer on a cookie sheet or baking tray (with raised edges).
Place the cookie sheet into the freezer, keeping it level, and freeze until the fruit is solid. This usually takes a day or less. Avoid leaving the berries uncovered for more than a few days to prevent desiccation (freezer burn).
Remove from the freezer and transfer the berries into plastic freezer bags or other freezer containers. If using bags, extract as much air as possible before sealing. You can do this by using a straw and sucking the air out of the bag.
Seal the container, label it and return to the freezer until needed.
Try to use the berries within 6 - 8 months.
Dry Pack Freezing (unsweetened)
Similar to dry freezing, but berries are more likely to stick together in clumps. Instead of spreading on a cookie sheet to freeze, put the fresh, unfrozen berries directly into freezer containers or plastic bags. Remove air from bags. Leave 1/2 inch headspace in other containers for expansion. Label and freeze. Try to use the berries within 6 - 8 months.