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Substituting chocolate in recipes

(article, Hank Sawtelle)

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I have a question about unsweetened chocolate and cocoa powder that arose when I tried to bake some brownies from scratch and discovered that I didn't have any unsweetened chocolate. The recipe called for 3 oz. finely chopped unsweetened chocolate melted into the butter before the eggs and the dry ingredients were added.

Cocoa powder seems to be unsweetened chocolate that is finely "chopped," so if I'm measuring by weight anyway, could I just substitute an equal weight of cocoa powder for the chocolate? What's the difference between cocoa powder and unsweetened chocolate, anyway?
— Jason Garner, Portland, Oregon

This is a pretty good call, Jason. Cocoa powder is very similar to unsweetened chocolate. The main difference is the lower cocoa-butter (fat) content in cocoa powder, so it doesn't hang together like unsweetened chocolate (or chocolate bunnies, etc.). 

You can substitute cocoa powder for unsweetened chocolate, but you should add fat to make up the difference. There's algebra involved, so you'll have to do some work for those brownies.

Chocolate is made from cacao beans, which are the seeds of a tropical tree, and are found inside of fruits (aka “pods”). The chocolate manufacturing process starts when the cacao farmer empties the pulpy pods onto the ground in a hot tropical mess for a few days to spoil. (No, I'm not making this up.) 

Spoilage, when it leads to something awesome like beer or chocolate, is more commonly called “fermentation,” but it's the same process. In this case, yeasts and bacteria break down some of the bitter and astringent compounds in the beans and prepare them for roasting, where the chocolate flavor we're familiar with fully develops.

[%image reference-image float=right width=400 caption="Grocery-store cocoa powder typically contains about 20 percent residual cocoa butter, whereas unsweetened chocolate contains about 50 percent cocoa butter."]

After roasting, the shells are removed from the beans, leaving behind “cacao nibs” (you sometimes see these on ingredient labels and menus). Nibs are ground into a paste called chocolate '“liquor”' (not booze, sorry), which is about 53 to 55 percent fat (cocoa butter). The rest is cacao solids. 

From here, the process can go in one of two directions: The liquor can be further processed into various forms of solid chocolate (including the unsweetened chocolate called for in your brownie recipe), or much of the cocoa butter can be pressed out of the liquor, leaving a dry cake that is processed into cocoa powder. 

Grocery-store cocoa powder typically contains about 20 percent residual cocoa butter, although versions as low as 10 percent are available to commercial bakers for some applications.

The unsweetened chocolate you are replacing is supposed to be about half cocoa butter. So an ounce-for-ounce replacement could mess up your brownie recipe by including too little fat and too much chocolate flavor (assuming such a thing is theoretically possible).

At this point I'll refer you, if you haven't already read it, to Mamster's [columns/bacon/cocoapowder "excellent work" newpage=true] breaking down various chocolate products, in which he recommends against substituting cocoa powder for whole chocolate, on the grounds that good cocoa powder isn't less expensive than good chocolate. 

I'll second this recommendation. However, you didn't ask me whether you should do it, you asked me whether you could. So let's assume we're beyond the point of no return: You have no access to whole chocolate, yet it's a given that brownies need to happen. What should you replace the missing fat with? And how much? (I'll assume you don't have bulk cocoa butter lying around in your pantry, but if you do, definitely use that.) 

The most specific substitution instructions I've found are from Wayne Glissen's text Professional Baking. Glissen recommends using vegetable shortening to replace the missing cocoa butter. However — and this is where it gets weird — “regular shortening has about twice the shortening power of cocoa butter, so only half as much is needed in many products.” (“Shortening power” is Glissen's term for the tendency of fat to inhibit gluten, which can make baked goods undesirably tough.)

Thus, Glissen's procedure is to: “1. Multiply the weight of the chocolate by 5/8; the result is the amount of cocoa to use.” And then: “2. Subtract the weight of the cocoa from the original weight of chocolate; divide this difference by 2; the result is the amount of shortening to add.” 

See? Algebra. Just like I promised. 

For the 3 ounces of chocolate in your recipe, the answer works out to about 1.9 ounces of cocoa powder and 0.6 ounces of shortening. Before you get too excited, Glissen recommends test-baking a small batch and adjusting the formula if necessary, because “no single substitution ratio is adequate for all purposes.” 

[%image equation float=right width=400 caption="Unsweetened chocolate is a combination of fat and cocoa."]

Is it starting to sound easier to just go to the store and buy some unsweetened chocolate? Probably. But if I were in a jam, I would totally try this substitution. And if I didn't have shortening, I'd use butter or vegetable oil.

Incidentally, if your brownie recipe includes baking soda, you shouldn't use “dutched” cocoa powder for the substitution. Dutched cocoa is treated with an alkaline substance (similar to baking soda) to raise its pH (which also mellows the flavor). “Natural” cocoa on the other hand, is quite acidic. Chocolate brownie (and cake, and cookie, etc.) recipes that include baking soda are counting on the natural acidity of the cocoa or chocolate to react with the baking soda and create carbon-dioxide gas for leavening. Dutched cocoa will not react with the baking soda, and the resulting brownies will be relatively flat, dense, and bitter from the unreacted baking soda.

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Also, if you're looking for other things to worry about, think twice if you're tempted to use a Hershey (or other brand) milk-chocolate bar you might have lying around. (Hey, it could happen. Emergency s'mores kit?) In addition to the extra sugar, the textbook On Baking warns that “the milk solids tend to burn.” (But for some reason butter is OK? Shady.)

Or you could ignore all of the above equations and finger-wagging and just wing it. At the end of the day, you'll still have some semblance of a brownie, and how bad can that possibly be?

p(bio). Based in Portland, Oregon, Hank Sawtelle has engineering, legal, and culinary degrees.


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