the most important step to freezing your blackberries is to wash them immediately when you get them home. even if i get in late in the evening on picking day, i get to work cleaning them that night.
i gently put about one gallon of berries in a sink full of water with a little vinegar, and give them a swirl. after letting them soak for a few minutes, i drain them in a colander. in the past, i used to soak them for an hour, rinse them, and then repeat two more times with cold water.
i have found that if time gets away from me, a three hour soak just 