Is there anything worse than cutting that first slice of pie and then watching the filling slowly slide out from under its cozy crust?
Like the chewy versus crispy cookie debate, the perfect slice of pie is also up for debate. For me, I like a pie, especially a classic fruit pie, to be slice-able and for the filling to hold its shape. Just is fine but not so much that it resembles soup. I want pie. I want a firm filling.
But how do we get that perfect slice? What’s the difference between each type of pie thickener? What about pectic? How do we choose the right thickener and the right amount for each pie?
All Purpose Flour
All-purpose flour is an easy solution, as you’re almost sure to have it in your pantry. Since it’s lower in starch, you’ll need more of it than you would higher-starch thickeners. Flour’s thickening power is about half as strong as cornstarch or tapioca. It adds a slight opacity to fillings. It’s good for apple or pear fruit pies. It does not need high temperatures to work making it a good all around thickener especially for pies that need to bake for a long time. Be aware, it can impart impart a distinct taste and color to fruit pies.
Sub: twice as much flour as cornstarch or tapioca
Cornstarch has a thickening power similar to Instant ClearJel and it is twice that of flour. Like flour, using it will impact the final look of your pie. Cornstarch adds a cloudy, semi-transparent look to the filling. It can also give filling a starchy taste if not cooked long enough or at a high enough temperature. For full effectiveness and thickening, make sure the pie filling is bubbling up through the crust before removing your pie from the oven. Cornstarch does not work well with acidic ingredients so add any of those ingredients after incorporating and thickening with the cornstarch. Can sometimes impart a chalky flavor. If heated too long, the thickening will lose some effectiveness.
Sub: half as much as flour, equal parts to tapioca or ClearJel
Tapioca (Quick or Flour)
Tapioca comes from the cassava root and is often found in two different forms for baking: quick cooking and flour. Quick-cooking tapioca (the little granules) makes filling bright and clear, but also gives it a stippled and somewhat sticky texture especially if it doesn’t fully dissolve. Filling mixed with tapioca needs to rest 15 to 30 minutes before baking, for the tapioca to soften. If using the flour variant, be sure the filling is bubbling by the end of the bake or the temperature won’t be high enough for the starch to do its thickening work.
Sub: equal parts to tapioca or ClearJel
Instant ClearJel keeps fillings thick through a great range of temperatures, making it ideal for pies that are frozen, before or after baking. What is it exactly? It’s typically modified cornstarch. It’s the secret ingredient used in most commercial pie fruit fillings. It has no floury, pasty or starchy flavor. Very easy to use and hard to overcook. Just mix with sugar prior to adding to fruit filling to avoid clumping. It also works well with acidic ingredients.
Sub: equal parts to tapioca or cornstarch
Fruit Juice Chart
|Apples||High||Needs the least thickener|
|Blackberries/Raspberries||Low||Needs more thickener, especially frozen variety|
|Blueberries||Med||Highest pectin of berries, needs less thickener|
|Cherries||Med||Fresh needs less than canned or frozen|
|Peaches||Low||Needs more thickener|
|Strawberries||Low||Juiciest fruit, most thickener|
Tips and Techniques
- Some science: heat causes the starch in the thickeners to bond with water molecules. The starch granules then start to enlarge like a balloon, absorbing the water around it. As the temperature rises over 150 F but below boiling, the rigid structure of the starch separates, creating a spidery web. This web prevents the movement of water molecules and results in a thick filling.
- If you are using cornstarch or flour as a thickener, it’s important to note that the filling needs to bubble to achieve thickening and to cook off the raw starch flavor.
- The pie topping will affect amount of thickener. An open, crumb, or lattice top, let more steam escape and require less thickener than a pie with a double crust.
- Supermarket fruit tends to be less juicy than local, farmer’s market fruit.
- Mix thickener with sugar before adding to a recipe to help avoid clumping.
- It’s okay to mix thickeners to achieve the right consistency especially with very juicy fruit. This may take some experimentation to get right but whoever complained about more pie!
- Let cool completely to allow juices to firm up. If you want to serve a warm pie, refresh in the oven by covering the cooled pie with aluminum foil and place in a 375 degree pre-heated oven for 15 minutes to crisp the crust and warm the filling throughout.
All of these thickeners work in approximately the same way: heat causes the starches in the thickeners to bond with the liquid in the pie filling and begin to swell, forming a more stable structure.
The difference between the thickeners is mostly about how they look and taste, interact with the filling itself, and the temperature at which they begin to thicken.
Each pie will require something a little different but don’t skip this critical ingredient to get that perfect slice. A little practice will make perfect!