What would make my pie filling not set up when using corn starch?

Deanna Jones


AntoniaJames February 17, 2015
Pam Anderson did a full analysis of peach fillings to make the best peach pie, in her excellent book, "CookSmart." Her many tests were for a cooked pie, so it may not be of much use in this case. (It's a fascinating exegesis, however.) If you're pouring a hot filling over fresh peaches, they obviously are releasing more juice. That juice needs heat to set up properly. The starchy filling is cooling while the peaches are releasing the juice; in fact, the heat from the filling on the peaches is probably causing more juice to release than otherwise. I would probably experiment with mixing the cooled filling with the peaches letting them sit (I'd do this in a bowl), and then see if you can gently incorporate the juice into the filling. A better technique might be to macerate the fruit in sugar in a separate bowl for 6-8 hours, to release the juices ahead of time, and then to use that juice in the stove-top filling itself. I'd probably let it cool off a bit but not all the way, and then mix it with the peaches.
I'm just thinking out loud here (the engineer in me in see-problem-solve-problem mode). ;o)
Deanna J. February 17, 2015
Thank you all for your comments. They are all very helpful. I appreciate the quick responses too.
C S. February 16, 2015
I don't know your exact problem but check out this link http://missvickie.com/howto/cooking101/cornstarch.htm. It lists a lot of different reasons why cornstarch may not work as you want it to. Good luck - Peach pie sounds delicious - I used to make a blueberry pie using that same technique.
Deanna J. February 17, 2015
Thank you for the link. I printed it out, so hopefully I will figure out the problem.
luvcookbooks February 16, 2015
I recently learned that over cooking can thin cornstarch based sauces. There's a magic moment between thin and thin. Maybe try a shorter cooking time??
Deanna J. February 17, 2015
This may very well be my problem. Thank you.
Woodside February 16, 2015
If the filling didn't reach a high enough temperature after the cornstarch was incorporated, it wouldn't thicken. The only other possibility I can think of would be insufficient amount.
Deanna J. February 16, 2015
It is poured over fresh peaches that are lining the bottom of the pie shell. The filling thickens on the stove while I cook it...but when it cools in the pie shell it is runny again.
Woodside February 16, 2015
It may be that as you add the cooked filling over the fresh peaches, the peaches release more juice, thinning the filling, especially if the filling is warm to hot. Just a thought.
C S. February 16, 2015
It's hard to know without more information. If it did not come to a boil (usually meaning when the filling bubbles and boils over if the filling is baked in the crust), or if there was too much acid in the filling. Could be several different reasons, can you share more details.
Deanna J. February 16, 2015
It is a filling for a fresh peach pie. It isn't cooked in the oven however. The filling is added to an already cooked pie shell. I always make sure it comes to a boil and thickens on the stove, but after it cools in the pie shell it is runny again..so I am not exactly sure what I am doing wrong. Should I cool it at room temperature before pouring into the pie shell? Should I pour immediately into the cooled pie shell and then put in refrigerator to cool? I am not really sure. But I am doing something wrong.
I have made it before successfully, but lately, not so much. :)
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