Blueberry Pie (Cook's Illustrated)

Published July 1, 2008. From Cook's Illustrated.

WHY THIS RECIPE WORKS:

When perfecting our blueberry pie recipe, we found that adding a peeled, grated Granny Smith apple, rich in pectin, helped thicken the berries and enhance their flavor.

MAKES ONE 9-INCH PIE

This recipe was developed using fresh blueberries, but unthawed frozen blueberries (our favorite brands are Wyman’s and Cascadian Farm) will work as well. In step 4, cook half the frozen berries over medium-high heat, without mashing, until reduced to 1 1/4 cups, 12 to 15 minutes. Grind the tapioca to a powder in a spice grinder or mini food processor. If using pearl tapioca, reduce the amount to 5 teaspoons. Vodka is essential to the texture of the crust and imparts no flavor; do not substitute.

INGREDIENTS

• Foolproof Pie Dough
• 2 1/2cups unbleached all-purpose flour (12 1/2 ounces), plus more for work surface
• 1teaspoon table salt
• 2tablespoons sugar
• 12tablespoons cold unsalted butter (1 1/2 sticks), cut into 1/4-inch slices
• 1/2cup vegetable shortening , cold, cut into 4 pieces
• 1/4cup vodka , cold (see note)
• 1/4cup cold water
• Blueberry Filling
• 6cups fresh blueberries (about 30 ounces) (see note)
• 1Granny Smith apple , peeled and grated on large holes of box grater
• 2teaspoons grated zest and 2 teaspoons juice from 1 lemon
• 3/4cup sugar (5 1/4 ounces)
• 2tablespoons quick-cooking tapioca , ground (see note)
• pinch table salt
• 2tablespoons unsalted butter , cut into 1/4-inch pieces
• 1large egg , lightly beaten with 1 teaspoon water

INSTRUCTIONS

1. 1. For The Pie Dough: Process 1 1/2 cups flour, salt, and sugar in food processor until combined, about two 1-second pulses. Add butter and shortening and process until homogenous dough just starts to collect in uneven clumps, about 15 seconds; dough will resemble cottage cheese curds and there should be no uncoated flour. Scrape bowl with rubber spatula and redistribute dough evenly around processor blade. Add remaining cup flour and pulse until mixture is evenly distributed around bowl and mass of dough has been broken up, 4 to 6 quick pulses. Empty mixture into medium bowl.

2. 2. Sprinkle vodka and water over mixture. With rubber spatula, use folding motion to mix, pressing down on dough until dough is slightly tacky and sticks together. Divide dough into 2 even balls and flatten each into 4-inch disk. Wrap each in plastic wrap and refrigerate at least 45 minutes or up to 2 days.

3. 3. Remove 1 disk of dough from refrigerator and roll out on generously floured (up to 1/4 cup) work surface to 12-inch circle, about 1/8 inch thick. Roll dough loosely around rolling pin and unroll into pie plate, leaving at least 1-inch overhang on each side. Working around circumference, ease dough into plate by gently lifting edge of dough with one hand while pressing into plate bottom with other hand. Leave dough that overhangs plate in place; refrigerate while preparing filling until dough is firm, about 30 minutes.

4. 4. For The Filling: Adjust oven rack to lowest position, place rimmed baking sheet on oven rack, and heat oven to 400 degrees. Place 3 cups berries in medium saucepan and set over medium heat. Using potato masher, mash berries several times to release juices. Continue to cook, stirring frequently and mashing occasionally, until about half of berries have broken down and mixture is thickened and reduced to 1 1/2 cups, about 8 minutes. Let cool slightly.

5. 5. Place grated apple in clean kitchen towel and wring dry. Transfer apple to large bowl. Add cooked berries, remaining 3 cups uncooked berries, lemon zest, juice, sugar, tapioca, and salt; toss to combine. Transfer mixture to dough-lined pie plate and scatter butter pieces over filling.

6. 6. Roll out second disk of dough on generously floured (up to 1/4 cup) work surface to 11-inch circle, about 1/8 inch thick. Using 1 1/4-inch round biscuit cutter, cut round from center of dough. Cut another 6 rounds from dough, 1 1/2 inches from edge of center hole and equally spaced around center hole. Roll dough loosely around rolling pin and unroll over pie, leaving at least 1/2-inch overhang on each side.

7. 7. Using kitchen shears, trim bottom layer of overhanging dough, leaving 1/2-inch overhang. Fold dough under itself so that edge of fold is flush with outer rim of pie plate. Flute edges using thumb and forefinger or press with tines of fork to seal. Brush top and edges of pie with egg mixture. If dough is very soft, chill in freezer for 10 minutes.

8. 8. Place pie on heated baking sheet and bake 30 minutes. Reduce oven temperature to 350 degrees and continue to bake until juices bubble and crust is deep golden brown, 30 to 40 minutes longer. Transfer pie to wire rack; cool to room temperature, at least 4 hours. Cut into wedges and serve.

RECIPE TESTING

LOOKS CAN BE DECEIVING

• 

  Pretty But Pasty
  

  Too much tapioca (or the wrong thickener, such as flour or cornstarch) results in a filling that holds its shape but tastes gluey and dull.

• 

  Fresh But Soupy
  

  With no thickener at all, there is plenty of fresh berry flavor, but the filling is loose and runny.

TECHNIQUE

NO-FUSS TOP CRUST

• 

  We used a 1 1/4-inch biscuit cutter to cut holes in the dough, but a spice-jar lid will also do the trick.

THE APPLE OF MY PIE

When making our blueberry pie filling, we found that if we used more than 2 tablespoons of tapioca, the texture of the filling took on a gummy consistency we didn’t like. But 2 tablespoons or less resulted in a filling that was too loose. Could we solve this problem with pectin, a gentle thickener that occurs naturally in fruit?

EXPERIMENT

As a control, we thickened one pie with 2 tablespoons tapioca. We then compared it with a second pie thickened with 2 tablespoons tapioca and a grated apple, which is high in pectin and has a mild flavor. (We hoped that grating the apple would make it less noticeable in the baked pie.)

RESULTS

As expected, the pie thickened with tapioca alone was loose and soupy. But the pie thickened with tapioca plus an apple had a naturally gelled texture that was just right. The apple bits seemed to melt into the berry filling during baking, boosting fruity flavor but leaving no textural sign of their presence.

EXPLANATION

Pectin is a natural substance, found in fruits and vegetables, that creates structure in a plant by helping to bind its cell walls together. This same substance is used to thicken jams and jellies into a set, but soft, mass. Pectin content varies from fruit to fruit and also within a plant (more pectin is found in the skin of a fruit than in its flesh, for example). Apples are a great source of pectin because they contain high levels of high-methoxy pectin, the best natural pectin for making gels. By mashing some of the blueberries and grating the apple, we helped to release the pectin from the fruits’ cell walls so that it could thicken the pie filling.

• 

  ON THE LOOSE
  Pie filling thickened without enough tapioca won't firm up. But too much tapioca leads to gumminess.

• 

  ALL FIRMED UP
  A little tapioca plus a grated apple created a juicy but sliceable filling.