We at America’s Test Kitchen wanted a pie that had a firm, juicy filling full of fresh blueberry flavor with still plump berries, and we also wanted a crisp, flaky crust.
To thicken the pie, we tried cornstarch as well as our glutenfree flour blend but preferred tapioca starch, which was subtle enough to allow the berry flavor to shine through. Too much of it, though, created a congealed mess.
Cooking some of the blueberries down to a saucy consistency helped us reduce the amount of tapioca required, as did adding a peeled Granny Smith apple that we shredded on the large holes of a box grater.
Rich in pectin, the apple helped thicken the berries naturally. Since gluten-free pie crusts can easily turn soggy, we found that preheating a sheet pan in the oven and baking the pie on the lower rack helped keep the crust crisp. (We also offer a gluten-free flour blend).
It’s not safe to place a glass (Pyrex) pie plate on a preheated baking sheet. If you must use a glass pie plate, do not preheat the baking sheet; note, however, that your crust will not be as crisp. This pie is best served the day it is made.
Start to finish: 3 hours
30 ounces (6 cups) blueberries
1 Granny Smith apple, peeled,
cored, and shredded
5 1/4 ounces (3/4 cup) sugar
2 tablespoons tapioca starch
2 teaspoons grated lemon zest
plus 2 teaspoons juice
1 recipe Double-Crust Pie
Dough (recipe below)
1 large egg white, lightly beaten
Cook 3 cups blueberries in
medium saucepan over medium
heat, mashing occasionally with
potato masher to help release
juices, until half of berries have
broken down and mixture is thickened and measures 1 1/2 cups,
about 8 minutes. Let cool slightly.
Place shredded apple in clean
kitchen towel and wring dry. Combine apple, cooked berry mixture,
remaining 3 cups uncooked berries, sugar, tapioca starch, lemon
zest and juice, and salt in large
Adjust oven rack to lowest
position, place foil-lined rimmed
baking sheet on rack, and heat
oven to 425 F. Roll 1 disk of dough
into 12-inch circle between 2 large
sheets of plastic wrap. Remove top
plastic, gently invert dough over
9-inch metal pie plate, and ease
dough into plate; remove remaining plastic. Roll other disk of dough
into 12-inch circle between 2 large
sheets of plastic. Remove top plastic. Using 1 1/4-inch round cookie
cutter, cut hole in center of dough,
then cut out 6 more holes, about
1 1/2 inches from hole in center,
evenly spaced around center hole.
Spread blueberry mixture
evenly into dough-lined pie plate.
Gently invert top crust over filling
and remove remaining plastic.
Trim dough 1/2 inch beyond lip
of pie plate, pinch dough edges
together, and tuck under itself to
be flush with edge of pie plate.
Crimp dough evenly around edge
using your fingers. Brush pie with
Place pie on preheated baking
sheet and bake until crust is light
golden brown, about 25 minutes.
Reduce oven temperature to 350 F,
rotate baking sheet, and continue
to bake until juices are bubbling
and crust is deep golden brown, 30
to 40 minutes longer. Let pie cool
on wire rack to room temperature,
about 4 hours. Serve.
DOUBLE-CRUST PIE DOUGH
Makes enough for one 9-inch pie
Perfect pie dough has just the
right balance of tenderness and structure. The former comes from fat, the latter from the long protein chains, called gluten, that form when flour mixes with water. Too little gluten and the dough won’t stick together; too much and the crust turns tough.
So presumably we would face mostly a structural issue with a gluten-free dough, since gluten-free flours are naturally low in protein. As our first step, we swapped in our gluten-free flour blend for the wheat flour in all the pie dough recipes the test kitchen has developed over the years. We produced workable doughs in every case, but an all-butter dough (which includes sour cream for tenderness) had the necessary richness to stand up to the starchiness of the gluten-free flour blend and was clearly the best starting point.
Although we weren’t surprised to find that the dough was still too soft and lacked structure, we were taken aback by how tough it was; on its own, the sour cream was not sufficient to tenderize a gluten-free dough. We solved the structural problem easily with the addition of a modest amount of xanthan gum, but flakiness and tenderness were still elusive.
In an effort to further tenderize our dough, we tested ingredients that are known to tenderize: baking soda, lemon juice, and vinegar. Vinegar was the clear winner, producing a pie crust that was not only tender, but also light and flaky. Like conventional recipes, this pie dough can be prepared in advance and refrigerated for two days; however, it is not sturdy enough to withstand freezing.
6 tablespoons ice water
3 tablespoons sour
1 tablespoon rice vinegar
13 ounces (2 3/4 cups
plus 2 tablespoons) ATK
Gluten-Free Flour Blend
1 tablespoon sugar
1 teaspoon salt
1/2 teaspoon xanthan
16 tablespoons unsalted
butter, cut into 1/4-inch
pieces and frozen for 10 to
Combine ice water, sour
cream, and vinegar together
in bowl. Process flour blend,
sugar, salt, and xanthan gum
together in food processor
until combined, about 5
seconds. Scatter butter over
top and pulse until crumbs
look uniform and distinct
pieces of butter are no longer visible, 20 to 30 pulses.
Pour half of sour cream
mixture over flour mixture
and pulse to incorporate,
about three pulses. Add
remaining sour cream mixture
and pulse until dough
comes together in large
pieces around blade, about
Divide dough into two
even pieces. Turn each
piece of dough onto sheet
of plastic wrap and flatten
each into 5-inch disk. Wrap
each piece tightly in plastic
and refrigerate for 1 hour.
Before rolling out dough,
let it sit on counter to soften
slightly, about 30 minutes.
(Dough can be wrapped
tightly in plastic and refrigerated for up to 2 days.)
Makes 42 ounces (about
9 1/3 cups)
It is important to bring
the mix to room temperature before using it in a
recipe. Be sure to use potato starch, not potato flour.
Tapioca starch is also sold
as tapioca flour; they are
interchangeable. See notes
at right about shopping for
rice flours and substitutes
for potato starch and nonfat
dry milk powder.
24 ounces (4-1/2 cups
plus 1/3 cup) white rice
7- 1/ 2 ounces ( 1- 2/ 3
cups) brown rice flour
7 ounces (1-1/3 cups)
3 ounces (3/4 cup) tapioca starch
3/ 4 ounce ( 3 tablespoons) nonfat milk powder
Whisk all ingredients
together in large bowl until
well combined. Transfer to
airtight container and refrigerate for up to 3 months.
per serving: 506 calories;
227 calories from fat; 26 g
fat (15 g saturated; 1 g trans
fats); 63 mg cholesterol; 339
mg sodium; 70 g carbohydrate; 7 g fiber; 34 g sugar;
6 g protein.
For more recipes, cooking tips and ingredient
and product reviews, visit
www.americastestkitchen.com . Find more
recipes like Blueberry Pie in
“The How Can It Be Gluten-
Free Cookbook .”