The solution: The longer it takes food to freeze, the larger the ice crystals will be. These big ice chunks destroy cell walls inside the food, so when it thaws, it loses structural integrity and turns mushy. Big frozen-food companies use special equipment to flash-freeze berries individually. This makes for small crystals, so the thawed product better retains fresh taste and texture.
To approximate an industrial quick-freeze at home, spread berries in a single layer (not touching) on a baking sheet, and place the sheet in the back of your freezer. The extra space allows more exposure to the cold, freezing the fruit faster and preventing it from clumping. Then transfer frozen berries to large zip-top bags.