5 Common Pie Thickeners and How They Work

updated May 1, 2019
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(Image credit: Christine Gallary)

Besides a flaky crust, getting the filling in fruit pies to thicken up but not turn into a gluey mess requires some know-how about different thickeners, how they work, and what works best for the particular pie that you’re making. Here’s a guide to five common thickeners so you can make the right choice when deciding how to thicken your classic apple pie or triple-berry summer pie.

How Starches Thicken

So how does starch thicken pie filling anyway? Heat causes starches to bond with water molecules and start swelling. After they reach the appropriate temperature, the rigid structure in the starch separates and creates a net of starch and water that stabilizes and thickens.

The temperature that each starch needs in order to thicken, however, varies, as does its ability to hold onto the bond for a prolonged period of time. Depending on what it’s made out of, starches also have varying flavors and textures.

Here’s a list of five common starches that are used to thicken fruit pies and the characteristics, strengths and weaknesses of each!

(Image credit: Christine Gallary)

1. All-Purpose Flour

  • What it’s made from: High-gluten hard wheat and low-gluten soft wheat. Contains about 75% starch.
  • Thickening properties: Flour doesn’t need high temperatures to thicken, but you do need more flour to thicken, about 1 1/2 times more than a purer starch. It thickens at at lower temperature than other starches and works great as an all-purpose thickener since you probably have it around.
  • Stability: Very stable and can stand up to prolonged cooking.
  • Appearance when activated: Gives food a matte, opaque appearance which looks fine with apple or pear pies but doesn’t look as attractive in summer berry pies.
  • Flavor: Pies thickened with flour can have a distinct wheat flour taste and be a bit gummy.

2. Cornstarch

  • What it’s made from: Corn that’s been soaked, milled, ground, sieved, and centrifuged. It is almost a pure starch.
  • Thickening properties: Cornstarch thickens more effectively than flour but needs higher temperatures to thicken. Toss it with sugar first to help it disperse better when it hits liquid.
  • Stability: While moderately stable, cornstarch can lose thickening power if heated too long or overwhisked once thickened.
  • Appearance when activated: While clearer than flour, fillings thickened with cornstarch will still be opaque.
  • Flavor: Cornstarch has a distinctive chalky flavor.
(Image credit: joannawnuk)

3. Quick-Cooking Tapioca

  • What it’s made from: The roots of the manioc or cassava plant that are made into pregelatinized pearls. It can also be sold finely ground into a powder.
  • Thickening properties: Works when hydrated and very good at thickening. Needs lower temperatures to release the starches and gelatinize.
  • Stability: Does not hold up well to prolonged cooking.
  • Appearance when activated: Bright and clear and has a smooth but sometimes gluey texture.
  • Flavor: Very neutral flavor.

4. Potato Starch

  • What it’s made from: A starch extracted from potatoes.
  • Thickening properties: Potato starch has the greatest thickening power of all the common starches and thickens at moderate temperatures. You’ll need larger amounts of potato starch, similar to regular flour.
  • Stability: Does not hold up well to prolonged cooking.
  • Appearance when activated: Clear and has a smooth but sometimes gluey texture.
  • Flavor: Mild flavor.

5. Arrowroot

  • What it’s made from: Arrowroot is a starch most commonly made from the roots of a West Indian plant.
  • Thickening properties: Arrowroot needs to be cooked at a higher temperature similar to cornstarch.
  • Stability: Can stand up well to prolonged cooking.
  • Appearance when activated: Clear and has a smooth but sometimes gluey texture.
  • Flavor: Neutral flavor.

For specific amounts, check out this great guide on the amounts of different thickeners needed for common fruit pies: Thickeners for Fruit Pies from King Arthur Flour.