My friend Nadine’s birthday is tomorrow; I’m going over to her place next week to celebrate, birthday cake in hand.  After the Kami Cake Debacle, I decided that I would do a little advance planning, even though 1) the oven is now fixed, 2) I am the proud owner of an oven thermometer, and 3) presumably I can put together a simple butter cake without undue panic.  Uh huh.  Exactly what I thought. So, I decided to test out my basic chocolate layer cake recipe today, juuuuuust to make sure everything was copacetic.  While I was at it, I thought that I might as well perform a little flour experiment: I’ve assumed for some time now that, of the whole grain flour options, whole wheat pastry flour would be the best substitute for cake flour, given it’s fine texture and lower protein content.  However, I’ve never really tested this hypothesis, so I decided that I would make one layer with WW pastry flour, and one layer with whole wheat all-purpose flour (100% whole grain winter white wheat).

Cake flour is a low-protein (approximately 8 %) flour that is very finely ground and is bleached with chlorine to further break down the proteins in the grain.  Now, I’m sure that makes lovely and delicious cakes but – eew.  Next time I want to bake a Clorox Cake, I’ll be sure to go out and buy some.  Pastry flour is also generally lower in protein, at about 8.5 – 9.5 %, than all purpose (10 – 12%) or bread (14%) flour, is made of softer winter wheat (white or red, but I most often see white wheat) and is finely milled. As far as I can tell, the only real difference between the two is the bleaching, although in whole wheat pastry flour, 100% of the wheat germ is kept with the flour (instead of de-germinating and sifting it away).  The whole grain all-purpose flour that I use, from Wild Hive, is 100% whole wheat flour, but it is winter white wheat, a softer grain and without the slightly bitter red germ of hard red wheat, and possibly is more finely  milled than their bread flour.

So, I broke out my well-worn Cake Bible, and after a little math, a lot of bowls, and the help of my trusty kitchen scale, I ended up with two lovely, chocolaty cake batters, exactly the same in every respect except for the flour.  I popped ’em in the oven, baked them at 350 degrees for 35 minutes, and then anxiously awaited the fun part:  The Taste Test.  But first…

Top is whole wheat AP flour; bottom is whole wheat pastry flour. The AP flour layer rose just slightly less than the pastry flour, but the pastry did sunk a bit in the middle. Pastry flour has a slightly more open crumb.

It’s a little hard to tell from this picture, but both layers actually rose nicely and were about 1 and 1/8 inch high; both layers were very moist and quite spongy, although presumably more dense than they would be with cake flour.  The edges of the pastry flour layer did get a bit burnt (I think it cooked a little faster than the other layer, so I should have taken it out of the oven sooner), even with aluminum cake strips on the pans. The AP flour layer was reasonably flat, but the pastry flour layer would have needed trimming if I were going to layer and frost it.  And the taste?  Pastry flour, hands down.  The pastry flour layer melted in your mouth, really tasted like a soft, delicious chocolate bar. The AP flour layer had a strange dryness; not that the cake was actually dry, as it was quite moist, but somehow there was a much more floury taste to this layer, and it sort of got stuck to the roof of your mouth like peanut butter.  It was passable, and would probably taste fine with frosting or filling, but the pastry flour was much tastier.  So – I was right all along.  But it’s always nice to have the data.

Adapted from Perfect All-American Chocolate Butter Cake in The Cake Bible by Rose Levy Beranbaum

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Whole Wheat Pastry Flour Chocolate Cake

EQUIPMENT

• two 9-inch by 1.5-inch cake pans
• electric mixer (hand or stand)
• cake strips (optional)
• kitchen scale (makes this much easier!)

INGREDIENTS

• 2 and 1/4 oz (1/2 cup + 3 tbsp) unsweetened cocoa (Dutch processed)
• 1 cup boiling filtered water
• 3 large eggs (5 and 1/4 oz)
• 2 and 1/4 tsp vanilla
• 8 and 1/4 oz (2 cups + 6 tbsp) sifted whole wheat pastry flour + 4 tbsp corn starch, combined (see Methods)
• 1 and 1/2 cups (10 and 1/2 oz) sugar (organic evaporated cane juice)
• 1 tbsp baking powder
• 1/4 tsp sea salt
• 1 cup (8 oz or 2 sticks) butter, softened

METHODS

1. Preheat the oven to 350 degrees F.  Take the butter out of the fridge to soften.
2. In a medium bowl, whisk together the cocoa and boiling water until smooth.  Cool to room temperature.
3. Prepare the cake pans: grease the pans, line the bottoms with parchment paper, then grease again and coat with flour.  If you have cake strips, soak them in a bowl of cold water.
4. In a small bowl lightly whisk the eggs, 1/4 of the cocoa mixture and the vanilla.
5. Tare a large bowl on your scale; add 4 tbsp of cornstarch, then add pastry flour to bring the total weight up to 8 and 1/4 oz.  Add baking powder, salt, and sugar and mix on low speed for 30 seconds to blend.  Add butter and remaining cocoa mixture; mix on low speed until all of the flour is moistened, then increase the speed to medium (or high speed on a hand mixer) and beat for 90 seconds to aerate and develop the cake’s structure.  Scrape down the sides.
6. Add the egg mixture gradually, in 3 additions, beating for 20 seconds in between additions.  Scrape down the sides and beat for 20 seconds more.
7. Scrape the batter into the prepared cake pans and smooth the surface with a spatula.  The pans should be about half full.  Bake for 25 to 35 minutes, or until a tester inserted near the middle comes out clean and the cake springs back when pressed lightly in the center.  The cakes should only start to shrink back from the sides of the pan once they have been removed from the oven.
8. Cool the cake layers in the pans, on wire racks, for 10 minutes.  Loosen the sides with a small metal spatula, if necessary, then invert onto wire racks; reinvert (using a plate) immediately and cool the cake layers on wire racks.
9. Once completely cooled, the cakes may be filled and frosted, dusted with confectionery sugar and served with fresh berries or strawberry puree, or triple-wrapped in plastic wrap and stored until needed.

OPTIONS

1. The original recipe calls for 8 and 1/4 oz of sifted cake flour (2 and 1/4 cups + 2 tbsp) and no cornstarch.  You may substitute each cup of cake flour with 3/4 cup of bleached all purpose flour + 2 tbsp corn starch, or obviously, whole wheat pastry flour as above.

STORE

Wrapped airtight, the cakes will last for 2 days at room temperature, 5 days refrigerated or 2 months frozen.

SEASON

Year-round.