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The best way to store blackberries for use at a later date is to rinse them and then put them on a cookie sheet in your freezer until they are frozen solid. Then transfer them to a Tupperware type container and keep in the freezer until you want to use them. You can easily take out a little or a lot depending on your recipe.
By patti Smith from Fontana, WI
I have found that if I store blackberries or raspberries in a airtight container (I use Glasslock), they last much longer than the ones stored in the paper pint container from the farmer's market. I tried storing some in each and the ones refrigerated in the Glasslock lasted almost a week where the ones in the paper container lasted only 2 days.
By Stephanie from Hillsboro, OR