Sunday, July 23, 2023

Gluten-Free Angel Food Cake

I had a lot of egg whites in the freezer (some of it from making recipes like this almond pie), so I decided to make angel food cake. Serious Eats argues that a gluten-free version is even better than the original because the gluten-free flours below create “a more delicate balance of starch and protein” than all-purpose wheat flour. (See here for more information about the choice of flours.)

I’ll confess immediately to using cornstarch instead of white rice flour (in a 1:1 ratio by weight), because as I was making the cake, I realized that I did not have white rice flour on hand (only brown rice flour and sweet rice flour, neither of which is a good substitute). Cornstarch is a relatively good substitute for white rice flour, though of course it’s best to use the blends specified below, and be aware that gluten-free flours are not interchangeable. I could have baked my cake a little longer, but it was really, really good! Seriously, no one would have guessed it was gluten-free – the crumb was perfect! It turns out that this works so well in large part because the protein in the egg whites gives the cake enough lift and structure that wheat flour isn’t strictly necessary. 

2 oz. (56 g) tapioca flour or arrowroot starch (about ½ cup) 
1 ½ oz. (42 g) white rice flour (about 1/3 cup) 
1 ½ oz. (42 g) cornstarch (about 1/3 cup) 
1 oz. coconut flour (about ¼ cup; 28g) 
1 tsp. (4 g) baking powder 
15 oz. (425 g) cold egg whites (about 2 cups), from 12 large eggs 
15 oz. (425 g) granulated sugar (about 2 cups) 
1 Tbsp. vanilla extract 
1 oz. (2 Tbsp.) freshly squeezed lemon juice, from 1 small lemon 
¼ tsp. (1 g) Diamond Crystal kosher salt; for table salt, use half as much by volume or use the same weight 

Adjust oven rack to the middle position and preheat to 350 °F. 

Sift tapioca flour or arrowroot starch, white rice flour, cornstarch, coconut flour, and baking powder into a large bowl. Whisk together until homogeneous, then sift mixture one more time to ensure total uniformity prior to mixing. 

Combine egg whites, sugar, and vanilla extract in the bowl of a stand mixer fitted with the whisk attachment. Mix on low to loosen, about 1 minute, then increase to medium-low (4 on a KitchenAid) and whip 3 minutes; the whites will be dense and dark. 

With the mixer still running, add lemon juice and salt. Immediately increase to medium (6 on a KitchenAid) and whip 3 minutes more; the meringue will be thin but foamy. Increase to medium-high (8 on a KitchenAid) and continue whipping until the meringue is glossy white and thick enough that you can see the pattern left by the wire whisk. This can take between 2 and 4 minutes, depending on the freshness of the whites and the horsepower of your mixer. When the meringue is ready, it should be soft enough to run off the wires when the whisk attachment is removed, but thick enough to mound up on itself like soft-serve in the bowl. 

Sprinkle flour blend on top and stir with a flexible spatula to roughly combine. Switch to a folding motion, scraping from the bottom up and folding through the center, until no pockets of flour remain. Scrape batter into a 10-inch aluminum tube pan (do not butter or grease pan); if you notice any small pockets of unincorporated flour, simply pause to mix them in. Bake until the cake is puffed, golden blond, and firm to the touch, about 45 minutes, or to an internal temperature of 206°F. (I did not measure the internal temperature of my cake, but should have baked it a tad longer.) 

Invert pan onto its stilts, over the neck of a wine bottle, or onto three soda cans (I balanced my pan on a single can because I’m a rebel) and cool upside down until absolutely no trace of warmth remains, at least 2 hours. Slide an offset spatula around the sides of cake to loosen, remove the insert, and slide spatula under the bottom as well. Flip onto a serving plate, pulling gently on the sides of cake to release it from the center tube. To serve, cut with a chef's knife, using a gentle sawing motion and only the slightest downward pressure. In an airtight container, leftovers will keep up to a week at room temperature.

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