Blueberry crisp filling always too watery


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My blueberry crisp is delicious but the filling is always too watery.
For 6 cups fresh blueberries I use 1 tablespoon of cornstarch. I realize now that is not enough.

Is cornstarch or flour better for thickening?

the filling recipe calls for :
  • 6 cups blueberries - fresh
  • 1/3 cup sugar
  • 1/3 cup brown sugar
  • 1 teaspoon lemon juice- freshly squeezed
  • 1 Tbs corn starch
  • 1/2 tsp cinnamon
 
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Sorry I thought I responded to your post....

Blueberries are high water content. They require 2 3/4 - 3 level tsp cornstarch per cup of blueberries - about 1 TABLESPOON per cup blueberries. Just be aware that cornstarch is cloudy and gets very gooey.

Tapioca starch is a better thickener for fruit desserts. But the best formula is by weight. Use 25% sugar to the weight of the fruit; 5.5% tapioca starch to the weight of the fruit.

Example, suppose the blueberries weigh 912 grams

912 x .25 = 228

983 x .055 = 50.16

912g blueberries
228g sugar
50g tapioca starch


Edit: starch needs to reach a certain temperature to chicken. Make sure your filling is bubbling in the center—that will indicate your filling is boiling, 212°F at sea level. That’s important.
 
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Sorry I thought I responded to your post....

Blueberries are high water content. They require 2 3/4 - 3 level tsp cornstarch per cup of blueberries - about 1 TABLESPOON per cup blueberries. Just be aware that cornstarch is cloudy and gets very gooey.

Tapioca starch is a better thickener for fruit desserts. But the best formula is by weight. Use 25% sugar to the weight of the fruit; 5.5% tapioca starch to the weight of the fruit.

Example, suppose the blueberries weigh 912 grams

912 x .25 = 228

983 x .055 = 50.16

912g blueberries
228g sugar
50g tapioca starch


Edit: starch needs to reach a certain temperature to chicken. Make sure your filling is bubbling in the center—that will indicate your filling is boiling, 212°F at sea level. That’s important.
Thank you for your reply.

1 tablespoon cornstarch per cup of blueberries seems way too much. I can see it being a thick glob.
I also just baked it for 30 minutes at 375*. I'm thinking now that wasn't enough time. and perhaps 45- 1 hour would cook it better.

Thank you again for the formula of berries-sugar-starch. I like this approach...a lot!
 
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Thank you for your reply.

1 tablespoon cornstarch per cup of blueberries seems way too much. I can see it being a thick glob.
I also just baked it for 30 minutes at 375*. I'm thinking now that wasn't enough time. and perhaps 45- 1 hour would cook it better.

Thank you again for the formula of berries-sugar-starch. I like this approach...a lot!



It’s not the bake time, but the temperature of the filling. More specifically it has to do with the temperature of the starch. It doesn’t matter how long it bakes, if it doesn’t come to a certain temperature, starch gelatinization will not occur. If starch gelatiniazation does not occur, thickening will not occur. It basic food chemistry.


You may think 1 tablespoon cornstarch per cup of blueberries is a lot, but unfortunately that is correct. The ratio of water to starch is the issue. Too much water will dilute the starch.

5 - 6 TBSP cornstarch for your 6 cups of blueberries.

And that is why pastry chefs do not use cornstarch. it is a horrible thickener, it clouds and it gooey.

If you do not want to take my word for it go on over to a source like king Arthur flour and look it up for yourself. I guarantee they’re going to recommend something very similar. The very minimum is going to be 2 1/2 teaspoons per cup blueberries.




this explains starch gelatinization



Scroll down to blueberries. They state 2 1/2 teaspoon cornstarch per 1 cup blueberries. Tablespoon is approximately 3 teaspoons. So that’s almost 1 Tablespoon cornstarch per cup blueberries. I’m sorry if those numbers bother you but that’s what it is. That’s why pastry chefs don’t use cornstarch.

 
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It’s not the bake time, but the temperature of the filling. More specifically it has to do with the temperature of the starch. It doesn’t matter how long it bakes, if it doesn’t come to a certain temperature, starch gelatinization will not occur. If starch gelatiniazation does not occur, thickening will not occur. It basic food chemistry.


You may think 1 tablespoon cornstarch per cup of blueberries is a lot, but unfortunately that is correct. The ratio of water to starch is the issue. Too much water will dilute the starch.

5 - 6 TBSP cornstarch for your 6 cups of blueberries.

And that is why pastry chefs do not use cornstarch. it is a horrible thickener, it clouds and it gooey.

If you do not want to take my word for it go on over to a source like king Arthur flour and look it up for yourself. I guarantee they’re going to recommend something very similar. The very minimum is going to be 2 1/2 teaspoons per cup blueberries.




this explains starch gelatinization



Scroll down to blueberries. They state 2 1/2 teaspoon cornstarch per 1 cup blueberries. Tablespoon is approximately 3 teaspoons. So that’s almost 1 Tablespoon cornstarch per cup blueberries. I’m sorry if those numbers bother you but that’s what it is. That’s why pastry chefs don’t use cornstarch.

Oh gosh thank you again for taking the time to explain this all to me.
I was so mistaken in what I thought about all this.

I got it now. I appreciate your help!

:)
 

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