So you’ve got a couple of pounds of peaches ripening on the counter, several pints of blueberries and the promise of apples in a couple of months. You’re thinking pie. Or a cobbler topped with biscuit dough. Or a fruit crumble with a crunchy oat-and-nut streusel-like finish.
Whichever dessert you choose, you’ll probably want to thicken the juices that fruits release during baking. Several ingredients help you do that with slightly different finishes. All-purpose flour, for example, turns juices slightly opaque, almost cloudy. Cornstarch, arrowroot, potato starch or rice starch make juices translucent and glossy. So does tapioca.
Most recipes will specify a thickener. If you don’t have the thickener called for, or if you plan to create your own dessert, here’s a general guideline: If 1 tablespoon all-purpose flour is used as thickener, you can substitute 1/2 tablespoon cornstarch (or potato starch or rice starch or arrowroot) or 1 tablespoon quick-cooking tapioca.
And while Fine Cooking magazine’s Carolyn Weil knows that some cooks like to use flour to thicken juices in a fruit pie, “I find the texture can be a bit gritty and that the flour turns the juices slightly cloudy,” she writes in “How to Break an Egg.” She prefers balancing the properties of cornstarch and quick-cooking tapioca.
“Both set clear when fully cooked and cooled. Using all cornstarch would make the filling gummy and all tapioca would make it seem dry,” she writes. “The cornstarch thickens while the tapioca adds texture without making the filling too gummy. If the tapioca is too pronounced, next time try grinding it to a fine powder in the food processor first.”
Almost as important as choosing a thickener, of course, is judging a fruit’s juiciness before you begin baking. Generally, the riper the fruit, the more juice it will produce during baking, especially stone fruits (peaches, plums, nectarines). Strawberries, raspberries and blackberries are much more delicate (and juicier) than blueberries or cherries.
