Raspberries are members of the Rosaceae (rose) plant family. A perennial, raspberries are differentiated by their color-red, black, purple and golden/yellow. The fruit may have originated in Turkey and then carried to Great Britain by the Romans. In the United States, the black raspberry grew wild with the red raspberry planted by settlers in the new land. The American red raspberry is grown throughout most of the U.S. and Canada. Its abundance makes it a good choice for freezing.
Raspberry selection before freezing
To freeze fresh raspberries, the Oregon State University (OSU) Extension Service recommends picking the berries in the early morning, when temperatures cool. The freshness of picked berries diminishes as the berries are exposed to warmth. Keep the berries shaded or refrigerated. If your berries are from the grocery store produce section or local farmer's market, keep them cool and away from sunlight as well. Never wash any type of berry until immediately before you are ready to begin the freezing process.
OSU's Extension Service estimates two pounds of fresh raspberries equal about one quart of frozen (or canned) berries. If you purchase or pick a thirty-six pound crate of whole raspberries, expect about eighteen to twenty-four quarts of frozen berries, so plan on ample freezer space to hold that larger amount.
If you plan to use the frozen raspberries in smoothies, ice cream or blended into a batter for cake or other baked treats, you do not need to freeze the berries individually. The raspberries can be frozen in a bunch, stored in freezer-safe bags or containers. Berries that need to maintain their individual shape after thawing, need to frozen as single pieces on a baking sheet before being stored in freezer-safe bags or containers.
Step one: Wash the raspberries in cool water, taking care not to rub each berry as they can bruise.
Step two: Allow the berries to drain in a colander or atop a clean paper towel. Be patient, the raspberries need to dry thoroughly for the best freezing results.
Step three: If freezing as a bunch, simply place the clean, dry berries in freezer-safe bags or containers and place in freezer. Be sure to label each bag first with the date. If freezing berries "individually" see step four.
Step four: Place the clean, dry raspberries in a single layer (not touching each other) on a baking sheet lined with wax paper. Place the baking sheet in the freezer. When the berries are frozen, remove from the sheet and place in freezer-safe bags or containers labeled with the current date.
The freezing method in step four allows more versatility. The berries won't stick together when you need to measure and add them to a recipe later. Allow the raspberries to remain in the freezer overnight to ensure each one is frozen completely.
Frozen raspberries will keep for about twelve months if sealed in freezer safe bags or containers.