Why is my cassava flour pie crust failing?

January 7, 2022 6:00 AM

Due to my partner's dietary restrictions I have been making pie and pastry crusts based on cassava flour rather than wheat flour and using this recipe as a guide. This has been mostly reliable but recently I have had a couple of pie crusts completely fail by turning soft, heavy, and kind of mealy in texture, rather than light and a bit crisp like a good pastry crust should be. Bleh. I haven't deviated from the recipe or changed my technique in an obvious way so what the heck is going on?

The recipe uses cassava flour, arrowroot starch, coconut oil, cold butter, and ice water and is prepared similarly to the way a regular wheat-flour pastry is made, by cutting the butter into the flour/starch, lightly binding the mixture together with water, and then resting it in the fridge before rolling it out.

One thing I did notice with the failed crusts is that I did not have to add any water at all in order to form the dough—the mixture already felt moist and kind of pasty despite having no added liquid whatsoever. We haven't changed brands of cassava flour recently. Maybe the environment is more humid? Otherwise I'm baffled.

(Note: partner's diet is based on the Auto-Immune Protocol food list with some additions like almond flour, butter, and eggs. Ingredients that are fine for other gluten-free baking, for example potato flour, aren't an option here.)

posted by 4rtemis to Food & Drink (8 answers total)

Maybe the issues are environment-related? I have no experience with cassava flour. But when it comes to wheat-based baking, I have to change my recipes up depending on the temperature and humidity.

I think the water would be an important thing to add. I don't know the science of it, but the flour will absorb the water and help things to bind. So I would add more cassava flour, and stick with the water.
posted by Cat Pie Hurts at 7:45 AM on January 7, 2022

I don't know anything about cassava flour, and I don't do gluten free cooking, but I do know some about baking science and I think it's the coconut oil that's the loser here. 1) it's a total fat, vs butter which is part fat part water and 2) the melting point of coconut oil is too damn high. It's liquid at room temp, so there's nothing there to re-firm and provide structure to the crust. I would lose the coconut oil in favor of more butter, or a vegan butter that's formulated to behave like butter, or shortening.

Has your home got warmer since your first few experiments, like it's winter now so the heater is on full time?
posted by phunniemee at 7:49 AM on January 7, 2022 [3 favorites]

Did you happen to switch brands or even open a new bag of the flours? Gluten amounts can vary so much. I am kind of surprised that coconut oil works but if you have success before then you should be able to adjust. First I would try resting in the freezer instead of the fridge to get the coconut oil really cold. Then if that didn't help I would reduce the amount of coconut oil and replace with butter. The crust will be a bit less flaky but it should still be crisp.
posted by muddgirl at 8:07 AM on January 7, 2022

Sorry, obviously not gluten amounts! But starch amounts.
posted by muddgirl at 8:09 AM on January 7, 2022

If it's winter where you are, it's likely drier than it was a few months ago and I wonder if you do indeed need to add the water back in despite initial feel. (Can you try adding clear alcohol? I would assume no, but it does a good job.)
posted by cobaltnine at 8:38 AM on January 7, 2022

I've found cassava flour frustratingly variable. I did finish reading Kat (The Loopy Whisk)'s Cookbook. Kat's a chemist, and the cookbook goes deep into how non-wheat baking happens, and she sometimes answers questions on her blog.
posted by Jesse the K at 8:55 AM on January 7, 2022

I use cassava flour, and I’m surprised this recipe ever works. I like cassava for smoothing out the grittiness of other grain-free flours, but it doesn’t have sticking power on its own, I assume due to the lack of protein. Since almond flour is an option, I would try a mix of the two.
posted by Comet Bug at 10:06 AM on January 7, 2022 [1 favorite]

I don't have an answer for why your recipe isn't reliable, but wanted to share one you may have success with. One of my favourite gluten-free bakers is Alanna Tobin-Taylor who has a blog called the Bojon Gourmet. She is a trained pastry chef.

She recently went on an AIP and many of her recent recipes now have options to accommodate that. Her regular gluten-free pie crust is the best I've made, and she re-worked her regular recipe to be paleo friendly. The link is here. I'm not sure if the chia or flax are okay for your partner, but it might give you some ideas!
posted by emsuro at 12:47 PM on January 8, 2022