Thickening fruit pies: No runs, no drips – no errors!


Does your strawberry pie look like this…


…or like this?

How the heck do you ENSURE your fruit pie filling will be perfectly thickened every time – no lava flow, no slumping…


…no puddle in the bottom of the pie pan?

The answer is…


You don’t. There’s no surefire, works-every-time thickener for every fruit pie out there.

Sigh. Death and taxes are still life’s only certainties.

After lots of experimenting with different fruits and thickeners, I’ve concluded there are just too many variables to guarantee perfectly thickened fruit pies EVERY time out.

That said – there are certain things you can do to increase your chances of success considerably. You can come very, very close to guaranteeing good results – even if you can’t QUITE get there.

Let’s start with the thickeners themselves.



Pictured above are the six ingredients we use here in the King Arthur test kitchen to thicken fruit pies.

Which is best? Let’s put ’em to the test.

Fresh and frozen blueberries; apples; strawberries; six thickeners. What’s the most efficient, most accurate way to gather data for analysis?

Theoretically, the best way would be to bake a pie using each combination. By my calculations, that would be 24 pies.

I’m a member of the King Arthur test kitchen staff, but I bake at home, using my own kitchen and single (sometimes balky) oven.

You ask, why don’t I take advantage of King Arthur’s wonderful kitchen facility, with its multiple ovens, “instant” dishwashers, and every ingredient and tool one could possibly want?

Because I want to replicate, as closely as possible, the experience YOU have at home: limited counter space; juggling batches of cooling cookies on and off a single cooling rack; laboriously scraping burned pie filling off a baking sheet (a wonderful reason to use parchment, folks).

So, bake two dozen full-size pies? There has to be a more efficient way. What would be quicker and easier, yet still yield valid results?


How about a muffin tin?


Light dawns on Marblehead! Forty-five minutes in a 350°F oven yields a good approximation of baked fruit pie filling: tender, bubbly fruit. Just two tins’ worth provides all the data I need.


I add a few more tests along the way, and chuck a few obvious failures. And at the end of the day, I’m able to examine over 2 dozen small mounds of thickened fruit, comparing and contrasting them for thickening ability, clarity, and flavor.


And here are the initial results. In my second round of tests, I use the information above to increase or reduce the amount of each thickener, in an attempt to produce a similar consistency in all the fillings.


One thing I notice right off is the clarity of the filling juice. The top row of photos shows blueberry and apple fillings thickened with flour. The bottom row, those same fillings thickened with Pie Filling Enhancer (a.k.a. PFE).

See how my lit flashlight is able to shine through the PFE fillings, while the cloudiness of the flour fillings dims the light?

Strike one against flour. While it’s probably the most ubiquitous ingredient in your kitchen, it doesn’t produce the prettiest fruit filling.

Now, I can hear some of you saying, “But I always use flour to thicken my fruit pies. It’s what my mom and grandma used.”

Great! If flour works for you, keep using it.

In fact, as you read through this post, you may find you disagree with some of my assessments. In fact, you may be a pie aficionado who, over the years, has worked out the perfect solution to all of your fruit filling challenges.

Again – keep doing what you’re doing! What works for you is absolutely what you “should” be doing.

And that’s the only time I like to use that loaded word, “should.” There are no Baking Police here; no absolute moral high ground, when it comes to baking.

Some bakers — and you may be one of them — take an opposing view, arguing that there’s a right and a wrong way to do things in the kitchen. But aside from basic food safety rules, I believe that there are many paths to any destination – find the one you like best, and follow it.

OK, back to the test results. Here are some general conclusions I was able to draw:

•Apples need less thickener than berries; in very general terms, about half as much.
•Fresh fruit needs just slightly less thickener than frozen.
•Flour is the only thickener that produces significant cloudiness, though cornstarch-thickened filling is somewhat more opaque than fillings thickened with other starches.
•Taste-wise, the best thickener is PFE. Its hint of ascorbic acid “brightens” fruit flavor; the other thickeners yield either neutral or flat flavor.
•Tapioca makes a filling that’s unpleasantly gluey (to my taste), even at low levels; the others make a filling with pleasing consistency.
•The thickness of some fillings (namely, those thickened with flour or cornstarch) changes a lot as they cool, while others (especially Signature Secrets) come out of the oven fairly close to what their final thickness will be.


And now, the $64,000 question: how much of each thickener do you use to get that perfectly thickened filling?

Not so thick it’s rubbery and tough…


…nor so thin it “bleeds” out of the crust.

Truthfully? The most I can say is, it varies. Fruit to fruit, pie style to pie style.

Pie style? Yes. Interestingly, I found that a double-crust pie needs more thickener than an open-faced pie, or one with a lattice crust, or pastry cutouts on top.

Makes sense, when you think about it. Even with vents in the top crust, that layer of pastry is preventing steam from escaping as the pie bakes. The liquid that would evaporate from an open-faced pie is trapped in a double-crust pie. Thus more thickener is needed to thicken the extra liquid.

My conclusion, after all these tests, is this:

Follow a recipe when making fruit pie.

Sounds like common sense, doesn’t it? But how many times have you made a fruit pie, and substituted raspberries for some of the peaches, or cherries for a portion of the blueberries? Or used flour as the thickener because you’d run out of cornstarch?

Good recipes are thoroughly tested, using the ingredients as written. If you want to make that perfect apple pie you see pictured in your cookbook, use the ingredients as written – no substitutions!

Another path you can take: combine just the fruit and sugar (no thickener), stir, and let rest for 30 to 60 minutes. Stir again, pressing down on the fruit so it releases as much juice as possible. Pour the accumulated juice from the bowl into a saucepan, and simmer until thick and syrupy. Pour over the fruit, and continue with the recipe as written.

One more thing you can do: record your results. Jot down the following on each fruit pie (or crisp) recipe you make:

•Season of the year;
•What variety of fruit you used (especially apples; e.g., Northern Spy, Granny Smith), and whether it was grown locally;
•Whether the fruit was fresh or frozen;
•Type of crust (single, double, lattice, etc.);
•Pan used;
•Baking temperature;
•Baking time;
•How long the pie cooled before you cut it (strong suggestion: overnight);
•Initial outcome: perfect, lava flow, too stiff, etc.;
•Outcome 24 hours after cutting (still perfect, puddled juice in pan, etc.).

If you take the time to record your results, you’ll be able to make adjustments to your recipe until eventually, you find that sweet spot: the ingredients, style, pan, and baking/cooling process that create the “perfect” fruit pie.

So, after several rounds of testing over a few days (which did, eventually, include some complete-with-crust, full-size pies), I’ve chosen my two favorite fruit pie filling thickeners:

Pie Filling Enhancer for apple pies; and Instant ClearJel for berry pies.

And the reasoning behind that decision?

PFE’s ascorbic acid adds a touch of welcome tang to apples; especially store-bought apples, which can taste bland.

And ClearJel, with its extra thickening power (ounce for ounce), is a good match for the large amounts of juice most berries exude as they bake.

Both have a benefit none of the other thickeners have: they work well with pies that will be frozen after baking, then thawed, as neither breaks down when frozen/thawed, like other starches do.

Oh, one more tip: Signature Secrets is perfect for no-bake fruit pies. It thickens instantly – no baking needed. Simply slice fruit/crush berries, mix with sugar, and wait until juices collect. Stir in Signature Secrets, continuing to add until the filling is as thick as you like; then spoon filling into a baked pastry or graham cracker crust.

And finally – DO NOT cut into a fruit pie while it’s hot! The vast majority of warm fruit pie fillings will collapse into the breach you’ve created by lifting out the first slice. Just to be safe, I like to let a pie rest overnight before cutting.

If you just can’t wait, and want to cut your pie while it’s just slightly warm (not hot), it’s good to have a pie dam on hand to stanch the filling flow.


So, now that you’ve read all you ever wanted to know about fruit filling thickeners, you should be able to turn this…

CranapplePie C0F

…into this.

You may find success right away; or it might take you a few tries. But if you follow the recipe; record your results, then use those results to fine-tune your next pie, you’ll soon be right up there with the best fruit pie bakers you know.


Ready to bake? Here are some recipes you might enjoy –

•Blue Ribbon Pie
•Bumbleberry Pie
•Paper Bag Apple Pie
•Presidential Cherry Pie
•Rustic Raspberry-Peach Pie
•Strawberry-Rhubarb Pie

And remember, if you ever need a hand – the friendly bakers manning our hotline are ready to help.


PJ Hamel

PJ Hamel was born in Wisconsin, grew up in New England, and graduated from Brown University. She was a journalist in Massachusetts and Maine before joining the King Arthur Flour Company in 1990, where she's been ever since. Author or co-author of three King Arthur ...


  1. Sandra Alicante

    Great post! Pie baking is one area that is certainly not an exact science. Luckily, even if you get it wrong, once you eat it, the taste is still fine!
    I would guess that commercially baked ones (if they actually have real fruit) follow the fill pies with pre cooked and thickened fillings route? It would be pretty near impossible to get consistent results otherwise due to variations in the fruit itself through the seasons.

    Thanks, Sandra – this was an involved but tasty project, as you indicate! And yes, I’d say commercial bakeries use pre-thickened or pre-cooked fillings for consistent results. Thanks for connecting here, as always – PJH

  2. Teresa F.

    I often make galettes with stone fruit. Our favorite is plum. Their level of juiciness is in between apples and berries. How much Instant Clearjel would you recommend to use for a galette?

    I would use about one tablespoon of instant clearjel per cup of fruit in your recipe!-Jon

  3. Barb Melrose

    I use something a little more natural and that is arrowroot starch. It is very easy to digest and better than cornstarch. For EACH quart of frozen blackberries or boysenberries, I use 2 TABS of arrowroot starch mixed with 1 TAB of flour. Mix well with some of the berry juice. Then bring all the berries/juice, 1 tsp. lemon juice, pinch sea salt & 1/2 cup sugar to a low simmer/boil until the filling thickens. Take off heat and cool before putting into shell. Then put on top crust and bake at 375 for 40 minutes. Any longer than this the berry mixture tends to bubble up and out of the pie. I order arrowroot starch on line through IHERB. It is around $8 for 20 ounces. Great for gravies too.
    Thanks for sharing Barb. I remember Graham Kerr, the Galloping Gourmet used to use arrowroot in his cooking. ~ MJ

  4. Heidi

    Great article. I love all the experimenting and insight. This is something I have struggles with as a novice pie baker. I am definitely going to try those two recommended thickeners. Especially since I promised my husband a pie a week for the whole summer! : )
    Holy crusts and fillings Batman! That’s a lot of pies! We’d love to hear what you have planned, maybe we can share in the fun at least via the ‘net. ~ MJ

  5. "Paul from Ohio"

    PJ this is MORE than a Blog post – it’s a Master’s Thesis!!!! Thank you so very much for this massive undertaking, keeping track of the results, and then translating all of that data into words that all of us, that care about such matters, can understand and put to use. More than once I’ve been confused about which thickener to use and often just toss in a sprinkle of Clearjel, hoping it will do the trick. Tremendous research effort on our behalf. Much thanks. Now take a vacation!!!
    Hee hee, believe it or not, PJ really is on vacation this week! Good call buddy! ~ MJ

  6. Jess

    What are the specific ingredients of the Enhancer, the Clear Jell, and the Signature Secret?

    I do not buy anything unless I can read the ingredients. Many things King Arthur sells look tempting, but I cannot afford to buy something only to find it contains something I’m allergic to in it and so cannot use. It would be very helpful if the ingredients were listed in the KA catalog and on the KA Shop site.

    Greetings Jess: if you visit each product page of the items in question, there will be a link in orange that will take you to PDF of the packaging with the ingredients listed. For example, here is the product page for the Pie Filling Enhancer: If you scroll down to the Description section, you will see the words in orange “nutrition information and list of ingredients” which is exactly what you’re looking for! I hope this makes it easier to help you find what you need! For any specific questions about a product, please call us directly : 1-800-827-6836 OR email us at Best, Kim@KAF

  7. Stephanie

    My neighbors came up with a solution when my cherry pie, made with fresh cherries picked from a neighbor’s tree shortly before baking, had a problem thickening. They just served the pie over ice cream, juice and all!

    Sounds like a yummy solution to me!-Jon

  8. Johnny A.

    For berry pies, for a thickener, shred a Granny Smith apple, wrap a clean kitchen cloth around it and squeeze all the water out of it. You are left with a natural thickening agent for your pies.

  9. Kay

    Wow!! Thanks for all your research. I agree with Paul, this is a Master Thesis. What a help and leap forward for pie makers near and far. You have brought clarity to my runny mess. Now all I have to do is refine my recipes. Love your note taking suggestions too…especially season, variety and to wait 24 hours. The last is hard to do though!

    SO hard to wait to cut into that pie, Kay… But the texture of the filling totally changes as it cools, and continues to change (in my experience) up to 12 or so hours later – so it’s worth the wait. Hey, you can always whip up a batch of cookies or a loaf of bread while your pie’s cooling its “heels”! :) PJH

  10. Irene in T.O.

    Gummy end result with tapioca means you used at least 2X too much. I use 2 tablespoons per 10″ pie for fresh fruit, 3 tablespoons for frozen including berries. Tapioca has to sit for at least 20 minutes with fruit and sugar before you put it in the shell. Then stir and you should see clear grains and a small amount of liquid. Too much liquid from frozen berries? add another tablespoon and let it sit. I usually add 2 tablespoons water to apples to get the juice going before the baking starts. This way I have perfect pie every time.

    Fantastic tips, thank you Irene! It’s always great to have experience shared with those who may not be familiar with a technique or ingredient. Cheers! Kim@KAF

  11. marcin

    A good tip from James Beard’s American Cookery: Use running water to wash the blueberries, rather than letting them soak in water, and dry the berries in clean dishtowels. It really helps to start with fairly dry blueberries.

  12. Katherine Isham

    Unpleasantly gluey…! And here tapioca is my thickener of ~choice~ because I find that, unlike flour, it doesn’t impart much texture. (I feel like flour/cornstarch gives pie a “chalky” texture.)

    Exactly why we should all feel free to stick to whatever pleases us best, Katherine – as I said, no “Baking Police” here! :) PJH

  13. Kellie

    Great analysis and I will try Clear Gel in my future berry pies.

    Meanwhile, I use a “trick” that I learnt from Bon Appetit mag about 30 years ago. Put the fruit, sugar, thickener and any flavorings into a bowl, let sit 20 – 30 minutes; if it is runny add thickener, if it too thick add sugar; let sit another 20 – 30 minutes and repeat until just right. Corrects for seasonal variation and so far has been almost fool proof; the only problem is when the fool (me) is in too much of a hurry to wait.
    Great tip, thanks so much for sharing! ~ MJ

  14. Joan

    Question. Rasberry Pie did not thicken due to too much juice. The recipe I used for the Rasberry Pie is: 1T cornstarch and 1 1/2C water and 3/4C sugar. I had too much rasberry juice from the berries and when I added the package of jello (no water) it still did not thicken. I was still hesitant of putting this in the pie shell. **NOTE The 4-5 Cups of berries were folded in after the above recipe was cool. QUESTION- Will this thicken through the night if I put them in different containers in the refrigerator? If not, what can I use now to thicken it up? I REALLY NEED YOUR HELP NOW!!
    Hi Joan,
    Gelatin based filling do thicken up as they chill, so refrigeration would be a good start. Good luck! ~ MJ

  15. William Thomas

    I am considering canning apple pie filling since it seems like a great opportunity to preserve the best possible apples while they are available this time of year. Many canned pie filling recipes call for the use of ClearJel, which I have never used before. I plan on experimenting first with individual pies. However, I find that canned apple pie filling recipes call for a great deal more liquid (water and/or apple juice). Why is this, and why wouldn’t the extra liquid just defeat the point of the thickener to some degree?

    1. PJ Hamel , post author

      William, having never canned apples, I don’t know for sure why the recipe would start with a lot of liquid. Maybe they call for simmering the filling before canning, and they assume much of the liquid will evaporate via steam? Just a thought… Readers, do any of you with more canning knowledge than I know the answer to this? PJH

  16. Allison Angier

    I have been trying to find something like this for years, to fix my pecan pie filling, which tends to “bleed” even when chilled for a couple of days. Thank you KAF!

  17. Linda VanMeter

    My 92 year young Mom has had this Fresh Strawberry Pie recipie for as long as I can remember and it is always good. As the binder for the 2 quarts of fresh berries you use 1 family size pkg. of strawberry jelllo, 4 Tbs. of cornstarch, 2 cups of sugar, and 3 Cups of water. Bring to boil for 3 min. cool to room temp and add fresh sliced berries.
    Yesterday I decided to make her one as a surprise but instead of the cornstarch I used the Pie Enhanser, and only 3/4 cup sugar. OH MY GOODNESS. I tasted the mixture while it was cooling, and I could hardly wait for the crust to bake so I could put it all together and eat it. Believe me I was not disappointed. I could have entered this pie in a contest and have won hands down. Momma said that it tasted better than hers. This was my first time for using the Pie Enhanser, and I just love it. The jel was clear and bright red, the ascorbic acid livened up the taste to wonderful. To be honest I ate 2 pieces last night and don’t feel guilty at all.

  18. John

    I made nine quarts of runny strawberry pie filling. I used corn starch which I probably let boil for too long or over-stirred or both. Is it possible to pour the contents from my jars and go back to the pot to thicken using Clear Jel?

    1. The Baker's Hotline

      That may be possible, but you will need to mix the instant clearjel with some sugar before mixing it into the filling. Otherwise it will become a clumpy mess! Jon@KAF

  19. David Stelzl

    Thanks for your post. Very helpful. I just made 20 pies for a wedding. Blueberry pie – runny! Of course! So, if I use this “clear jel” stuff, it should fix my problems? Do I just substitute it for the amount of corn starch called for? Also, where can I purchase the Clear Jel? Also, you said something about just cooking the filling with the cornstarch before putting it in the crust. How do I know how to adjust the temp and time if I do it that way?

    1. The Baker's Hotline

      Hello David,

      Instant clearjel will certainly help and we even have a whole guide to pie thickeners. We sell instant clearjel on our website and through our paper catalogue. If you pre-cook your filling, you will just need to bake your pie until the crust has fully browned to your liking. Jon@KAF

  20. Harvey Green

    I have been baking pies for some time using tapioca flour as my thickener. It works like a charm except for those occasions when we cut into the pie while it is still warm. I’ve also substituted KAF white whole wheat flour for half of the white flour in the crust to increase the nutrition/glycemic index of the crust, with little or no reduction in tenderness or flakiness. I also have tried a 50/50 mix of butter and Smart Balance to reduce saturated fat in the crust, also with good results. One of the most important things to do is to read about crusts and pastry in the KAF Baker’s Companion. I think it helps to get the theory more comprehensible. At least it did for me. I’d rather use sugar in my pies but my doctor would rather I didn’t, so I shall be experimenting in that department soon. Any help or suggestions from others will be very much appreciated. Thanks.

  21. Hasan A

    Thank you so much! this and your crash course in pie thickeners has helped me perfect my Strawberry Blueberry Pecan Streusel Pie for the family thanksgiving this year :)


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