Some of us are in the middle of it, some have seen strawberries come and go for this year, and some of us are still waiting for blueberries. Berries are a favorite for jams, whether a full flavor using one berry, or in combinations that allow our creative streak to show. Strawberry-raspberry, blueberry-blackberry, or even 3 or more berries in combination. Yum! As I write this, I’m past my morning breakfast decisions but now my mind is thinking ahead to what I can stir into my yogurt at lunch.
Another way to preserve our delicate, hand-picked berries is by freezing. Now we can start thinking about future pies, cereal toppings, or a quick, refreshing smoothie.
A dry pack is simply placing clean berries in freezer containers, sealing the container, and freezing. Unless they are tray packed (see below), they might clump together and be difficult to separate into individual berries. Note: If you do wash blueberries before freezing, dry blueberries completely after rinsing, or else the moisture on the blueberry skin will cause tougher skins.
A tray pack works well to help maintain the shape of each individual berry and keeps them easy to remove from the container and separate from each other. This method is called a tray pack because after rinsing the berries, you spread them in a single layer on a shallow tray (like a cookie sheet), then carefully lift the tray into the freezer without causing berries to touch each other. As soon as they freeze, seal the berries in an airtight container and place them back into the freezer so they don’t get freezer burn.
A sugar pack is like a dry pack but with one extra step – gently mix ¾ cup sugar per 1 quart (1⅓ pounds) berries before filling into freezer containers, sealing, and placing in the freezer. You can view step-by-step directions and photos for a sugar pack by selecting the PowerPoint presentation under “Strawberries” on the National Center’s ‘Freezing’ page.
A syrup pack surrounds the berries in a sweetened liquid, changing the sweetness and texture of the berries quite noticeably. Based on the natural sweetness of the berries and your own preference, you can decide the proportion of sugar to water from very light syrup (10% sugar) to very heavy syrup (50% sugar). More tart berries may produce the most desirable flavor from using a 40%-50% syrup. Exact proportions for the range of syrups are listed on this Syrups chart, along with directions to make the syrup and notes about replacing part of the sugar with corn syrup or honey.
Crushed or puréed is an option for berries like blueberries and huckleberries that you might use an ingredient in other recipes. The berries can be crushed, pressed through a fine sieve or puréed in a blender or food processor. Mix 1 cup (or 1⅛ cups) sugar with each quart (2 pounds) of crushed or puréed berries.
IMPORTANT! If you add sugar to the berries before freezing (as in the sugar pack, syrup pack, or crushed/puréed), then label the container with exactly how much sugar you add, so that you can include that quantity as part of the amount of sugar called for on the ingredient list of your final product recipe. If you know you want to use the fruit in jam later, you can also measure the amounts of sugar and fruit now for a specific recipe and freeze those together; then use the total contents when thawed to make the jam.
For all types of pack, remember to leave at least ½-inch headspace (more for some styles of pack; see chart for exact measurements) between the berries and the lid of each container so that the containers don’t break open while expanding in the freezer.
And most importantly, protect your fragile berries with the right kind of packaging for freezing. You don’t want the air inside the freezer to dry out your packs, or for flavors from one food to mingle with others. Freezer-weight plastic bags with good tight seals are a must if going the bag route. Glass jars with straight sides or wide mouth openings, plastic freezer boxes or re-purposed plastic tubs from frozen whipped toppings work well (as long as the seal between the lid and bottom is still intact and not misshapen from use).