Bumbleberry pies are not filled with fruit called bumbleberries, but rather are filled with a combination of fruits. The name is derived from the fact that, while these desserts vary, they usually feature mostly berries. Common filling combinations include raspberries tossed with blueberries, and blackberries, or cherries mixed with apples, strawberries, and pears. Some home cooks balk at making bumbleberry pies because the baker is at the mercy of unpredictable flavors. Almost anyone can make a delicious bumbleberry pie, however, if he or she chooses only perfectly ripe fruits, carefully considers flavor combinations, adds the right amount of flour or cornstarch to the filling, and lets the pie cool fully.
Before baking begins, one must always look over the fruit. Unripe, soft, or moldy fruit will give a pie a sharp, unpleasant aftertaste. Each piece of fruit chosen for bumbleberry pie must be firm, at the peak of color, and free of mold or bruises. In the cases of apples and pears, one may cut away bruises on otherwise fine fruit. This reduces waste.
Bakers rarely plan to make a bumbleberry pie, and rather end up combining filling ingredients when they discover a shortage of just one kind of fruit. Knowing how the flavors will taste together is important. Pairing milder fruits with very sweet fruits, like cherries and apples, typically balances the sweetness in the pie. Combining very tart fruits with sweeter fruits, like blueberries and strawberries, also creates a balanced flavor. A bumbleberry pie made with two very sweet fruits or two very tart fruits will likely have an overwhelming or less than perfect flavor.
Flour is the secret to achieving a gooey, thick pie filling. Fresh fruits usually shrivel a little during baking and leach out some of their juices, but not all of them. Pie filling without flour will simply create a fruity soup inside the pie crust. Adding about 3 tablespoons (28 grams) of flour to the filling should soak up the juice and thicken it, to create the desired syrupy pie.
Some cooks prefer to use frozen fruit for bumbleberry pies. It is available year-round and frozen at peak ripeness, so the flavor is usually good. Frozen fruits release a lot of liquid when cooked because their juices are ice until the heat hits them. Cooks using frozen fruit must add at least 1/4 cup (about 57 grams) of flour or cornstarch to the filling to keep the pie from becoming watery inside.
The last, best tip for making bumbleberry pies involves cooling time. When the pie comes out of the oven, the inside will be liquid and bubbly, like hot molasses. If allowed to cool for at least two hours, the filling will thicken to a gel-like consistency that will stay together in a nice, neat triangle when cut and served. When presentation is important, allowing the bumbleberry pie to cool is essential. Following these tips should yield a lovely bumbleberry pie every time.