When Baking Recipes Don’t Scale

So then, if baking recipes scale about 99% of the time, in what instances don’t they scale? Oh sure, put me on the spot readers Robin, Carl, Heather, Sandi and Monica. But that’s a really good question. Most incidences of non-scaling have to do with chemical leaveners — especially baking soda, for the simple reason that once you get soda wet in the presence of an acid, the leavening reaction tends to happen quickly. So quickly that it can peter out before you get you’re panned…whatevers…into the oven. This was especially true in our grandmothers’ day (these days soda manufacturers have tweaked the product so more of the bubbling action happens when the soda gets hot) but it’s still a risk to the contemporary baker.

Baking powder is less prone to the petering-out problem, though the wetter the mixture, the faster you’ll lose your pop. This is why some pancake batter recipes — even though they don’t contain baking soda — explicitly state that they can’t be doubled. The writer calculated that by the time you’d griddled all your cakes the last few would have the texture of frisbees.

Reader Mary correctly observed that batters for very large wedding cake layers don’t scale, and that you must cut back on your leavening as the pan gets broader. The reason for this has to do with physics more than chemistry, for the reality of broad, flat layers is that pan walls provide rising batter with support (mostly by facilitating heat penetration, which helps the batter set). The farther out into the center of the pan you get, the more unstable the cake becomes. This is why big sheet cakes often fall in the middle: they rise, can’t support themselves, and collapse. Cutting back a little on the leavening creates a slower rise, which gives the center of the cake more time to set and reinforce itself as it pushes upward. You lose a little in volume, but you gain a flatter center.

10 thoughts on “When Baking Recipes Don’t Scale”

  1. I can think of a time when recipes don’t scale proportionately… In sugar syrup recipes. When cooking sugar syrups to various stages (i.e., soft-ball, hard-crack, etc.) the idea is to increase the sugar concentration by driving out the water. You certainly can increase the size of a batch of syrup, but if you increase the amount of water proportionately as you scale up the sugar quantity, all you’re doing is making it take longer to reach the desired sugar concentration. That has two potential negative side effects. One, it can cause the syrup to yellow and two, if the water is not distilled (which it typically is not) can make the syrup taste slightly brackish at the end. The ratio of water to sugar needs to go down as plain syrup recipes are scaled up.

    1. Nice comment, Barry! I’d have never thought of this and that’s extremely useful expertise.

      Cheers,

      – Joe

      1. Yes I think so, but I don’t think the function of water in, say, a recipe for caramel, is terribly clear in most recipes. If the recipe writer calls for, say 1/3 cup of water to a cup of sugar, I don’t think most people understand that the quantity is mostly arbitrary, that it will mostly all boil out anyway, and that a 1/4 will work just as well. Most people would just follow the quantities without thinking too much about it, or that’s my feeling at least.

        – Joe

  2. What about scaling (up or down) with stirred custards? Also, if you want the custard to be pudding-thick or eggnog-thin does the ratio eggs to other ingredients need to change?

    1. Hey Jen!

      As far as I know they scale the same way, though making a huge amount of stirred custard would prevent certain logistical challenges in terms of heating the whole mass evenly. As far as consistency is concerned, indeed so, the lower the ratio of egg the thinner the custard will be.

      – Joe

  3. What about Michael Ruhlman’s book “Ratio”? I just received my copy the other day and haven’t had a chance to read very much, but it seems to contain some universal formulas. Have you read this book? Do you know if the formulas really work?

  4. Thanks Joe -that’s pretty much what I was taught by my Mum, too long standing with the pikelet mixture-the baking powder loses its oomph and with big cakes the weight of the dry ingredients is just too heavy to be raised and supported by the raising agents. 🙂

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