Food Nerd answers your science-y questions


Why doesn’t my whole wheat bread ever rise properly?

One of the things people ask me about this Food Nerd gig is, “Don’t you ever run out of things to talk about?”

Well… yes. And so I ask for help. Sometimes in person, sometimes over the phone, and, now, online. I was going to put out a call for reader questions, but I was afraid that nobody would ask me anything and I would look like a total knob. Hey, apparently it happens to everyone.

My pals came through, and now I have a whole pile of questions to answer. I’ve decided to group them thematically, under headings like, “Folks who can’t Eat Anything, and the People who Love them,” “Won’t Somebody Please Think of the Children?” and “Now, What am I Supposed to do With This?” But to start things rolling, here’s a bit of science because, really, it’s all about science, isn’t it?

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Why do recipes ask you to separate flour/dry ingredients from wet ones? Is it for the sake of the texture of muffins/cookies and the like, or for some other reason?
– Laura

It’s for a very good reason, I assure you. You’ll find this instruction mostly applies to muffins and “quick breads” like banana bread and zucchini loaf. The reason they’re called “quick” is this: their leavening (rising) action comes from baking soda or baking powder, and it’s pretty much instant. Baking soda starts to work when it comes in contact with some nice acidic liquid, like buttermilk or lemon juice. Baking powder has built-in acid (more on this later), which kicks in when you mix it with any wet ingredient. The reaction is the same as when you did the volcano experiment back in school: acid plus base makes gas. The flour and eggs and everything else in your batter trap the gas, and the muffins puff up nicely.

The whole thing happens fast. Double-acting baking powder draws the process out by kicking in as soon as it gets wet and then oomphing up again once it is exposed to heat, but even with the double oomphing, if you let your batter get a little bit wet, and then add in some more dry ingredients, and fiddle back and forth, most of your leavening action will have burned itself out by the time you get your muffins into the oven, and you’ll end up with hockey pucks.

There’s a second reason, too. Muffins are fairly delicate goodies, and will turn out tough if you stir them too much. I’m sure most of us have done this at some point. Stirring encourages the development of gluten, which is awesome when you want a big fluffy loaf of bread, but bad if you want a nice, crumbly muffin. If you have all your dry ingredients together, and then add all your liquid at once, you can stir your batter with just a few quick strokes and you’ll have delightful, airy muffins instead of dense, doughy ones.

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Why doesn’t my whole wheat bread ever rise properly?
– Susan

Um… that depends on what you mean by “properly.” Whole wheat bread never rises the way white bread does, because white flour is lighter, finer, less oily, and, let’s be honest, full of nothingness. The bran, oils, and general wheat-ness of whole wheat flour weigh everything down and prevent gluten strands from forming with wild abandon; in white flour, gluten strands grow uninhibited, and that’s what allows the bread to fluff up so much. Floofy breads that claim to be 100% whole wheat generally have piles of junk in them to help them rise up in this most unnatural fashion (just check out the ingredients list).

If you’re using a recipe meant for white flour, you might have to increase the amount of liquid you use; whole grains are thirstier than refined ones, and bread without enough liquid will end up suitable only for construction or hand-to-hand combat. Whole grain flours go rancid very easily if they’re not refrigerated, so make sure your flour is fresh, and keep it that way in an airtight container in the fridge or freezer. If neither of these things seems to be the trouble, try substituting warm soda water for the liquid in your recipe: the carbonation might give your bread that extra lift it needs.

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What the heck is cream of tartar and can I just use baking powder instead?
– Gay

Don’t do it, Gay! They’re not remotely the same! Put the baking powder down!

Actually, they’re not completely unrelated: in baking powder, cream of tartar (that’s potassium bitartrate, if you’re wondering) is combined with baking soda (sodium bicarbonate) so that there are both acidic and basic components: add any liquid at all and they’ll react with one another. But on its own, cream of tartar has no leavening power whatsoever.

What does it do, then? The main use is in making meringues and meringue-based cookies like snickerdoodles; the cream of tartar stabilizes the egg whites and keeps them from deflating too easily. It is also an important ingredient in some icings, like the relatively inedible sort you use on a gingerbread house. Baking powder would definitely not do in either of these recipes.

In case you’re put off by the cryptic name “cream of tartar” or by the laboratory-sounding “potassium bitartrate,” rest assured that the stuff is completely natural; it’s a byproduct of the winemaking industry. When grape juice ferments, white crystals precipitate out of it, and those white crystals, when refined, are what we know as cream of tartar. Nothing to be afraid of, and definitely useful to have around the house.

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