Open Freezing
This summer we had a large crop of raspberries which I froze to use later. They are now one solid block of ice. Is there any way I can freeze them so that I can measure out the amount I need rather than having to chip chunks out of a block?
--Joan
You can freeze berries, beans, and other fruits or vegetables using a technique called open freezing to keep them from forming a solid block. To do this, rinse the fruit or vegetable to remove any dirt or foreign particles. With some foods like beans, carrots and the like, larger pieces can cut up into mouth-sized bites. If necessary, blanch the food, and then dry it completely.
Place the food in a single layer one or more cookie sheets which have been lined with parchment paper so that the pieces are not touching. Put the cookie sheets into your freezer and leave them until the food freezes solid. Depending on the size of the pieces, this can take a couple of hours or more. Do not, however, leave the food like this for too long as prolonged open exposure to the air in the freezer will cause loss of quality.
Make sure to lay the sheets flat, so that the food doesn't all slide to one end and the pieces touch one another. Do not stack the cookie sheets one on top of the next as this will delay freezing, and may damage the food. There should be plenty of air flow over the top of each sheet.
Once the food is frozen, it can be removed from the parchment paper and put into labeled, resealable freezer bags or containers for longer storage.
It is necessary to make sure that the food is completely dry before open freezing or it may stick permanently to the parchment paper. I prefer parchment paper, however, as its silicon coating reduces the chance of this happening and if something does freeze to it, I don't care if it gets torn.
The University of Missouri Extension branch has a list of vegetables and the blanching method and times to use at this link. Blanching slows down enzymes that can cause food to lose its color or quality.