What’s up with this icing?

Cool isn’t it? A pre-made caramel combined with milk, butter and baking soda, then boiled to the soft ball stage. What the…?

The baking soda is the real curve ball here. What possible use is baking soda in a pot of boiling milk? Those who have ever made dulce de leche know the answer: it causes the milk to brown at a relatively low temperature. It’s an aesthetic thing in the context of this icing. It simply gives the mixture a nice tan color, which is important for the presentation of something called a “caramel” icing.

But what sort of browning happens in this sort of wet, watery environment? The answer is the Maillard reaction. Now, don’t go assuming that just because I just used the term “Maillard reaction” that I actually know what the reaction is, how exactly it happens, or what its products are. It’s one of the least understood reactions in food science. However that doesn’t stop a lot of people — from chin-stroking foodies right up to learned food scientists — from throwing it around all over the place. Ah yes, clearly the Maillard reaction, interesting….

It’s a weasel word, basically. Something you throw out to sound smart when you’re not completely sure what’s going on. Every science has a few of those. Chemists use the words like “catalyst” or “enzyme” to explain mysterious occurrences. For physicists the magic effect is frequently created by “resonance.” I use them all variously to try to explain to Mrs. Pastry how yet another grease stain managed to appear on one of my new shirts. She never buys any of it.

But where was I? Ah yes, the Maillard reaction. Ehem. All you really need to know about the Maillard reaction is that it occurs when proteins are exposed to heat. The proteins break into their component parts (amino acids) and then start recombining in all sorts of weird ways. Think of a toddler trying to reassemble her big sister’s LEGO masterpiece after she accidentally smashes it. I have no idea what those things are supposed to be, honey, but none of them look like the Taj Mahal.

Some of the odd new compounds are brown pigments, which is where the color comes from. As for the many hundreds (possibly thousands) of other whatsits that result from this process…no one knows what they all are. And if you’re thinking that the Maillard reaction is very similar to the caramelization of sugar, you’re right.

Normally you need some pretty big heat to create the Maillard reaction, a fry pan, a grill, a deep fryer, a very hot oven. However you can get the Maillard reaction going at a much lower temperature if you raise the pH. And that’s where the baking soda comes in. Added to the mixture it causes the milk proteins to start breaking up around 220 degrees Fahrenheit.

So, in this icing you basically have a real caramel mixture for flavor, and that’s added to a basic boiled icing that’s been spiked with baking soda for extra color. It’s ingenious, really. I can’t wait to try it.

15 thoughts on “What’s up with this icing?”

  1. Another thought on the baking soda: milk heated with acid will curdle every time, and caramelized sugar becomes more acidic as it darkens. I like my caramel reasonably dark, so I’ve run into problems with curdling milk on more than one occaision. I find it also helps to use plain refined white sugar, as a blonde organic sugar (with a little residual molasses left in) will contribute to curdling. Looking forward to seeing the cake!

  2. Very interesting! And thanks…how about pronunciation for Maillard, (for when I throw that word around, trying to sound smart) I’m thinking ‘my-yard’

  3. Assuming it’s French (which it looks like), it would be something like “my-YAR” with the “r” pronounced in the back of the throat (rather than by the tongue behind the teeth as in English) – pay no mind to the final d, it’s silent, and the double l is prounounced as a y. Because if there’s one language that rivals English for its disconnect between orthography and pronunciation, it’s French.

    You’ll still sound smart if you Anglicise it, though 🙂

    1. I’m going to put my foot down and declare that from now on, at least on this blog, we’ll pronounce it the Kentucky way: MAY-lerd.

      End of discussion!

      – Joe

  4. I would’ve never guessed baking soda would be responsible for all that. What a good thing to know. Thanks for the info, Joe 😎

  5. So the whole put a can of condensed milk in a pan of boiling water makes caramel because of the pressure cooking and thus shortens the time? or perhaps they are a bit more base as well… hmmm.

  6. Joe, in making peanut brittle, the sugar syrup mixture turns from being translucent to totally opaque when the baking soda is added. I always find it absolutely fascinating to watch. I presume something similar happens in this recipe? Is that also part of the Maillard reaction or something else? The texture also changes in the peanut brittle because of the baking soda, from stretchy and, caramelly, to a very loose, egg white batter type consistency. Obviously that’s partly due to the foaming action, but is there anything else going on to cause that? And does that happen in this frosting too?

  7. Hi Joe,

    I loved this post. I’ve been using small amounts of baking soda to encourage better browning in cookies, cakes, muffins, etc., for a long, long time. (Pale items just don’t look tasty or photograph well.) But I never really understood why it worked. A great piece of info to know!

    BTW, you are so right about chemists using “enzymes” to explain what they can’t explain. LOL!

    1. Hey Nancy!

      So glad you chose this moment to get in touch. I meant to tell you how much I enjoyed your post on writing and wordiness. We in the blogging community can’t hear that advice often enough! Cheers,

      – Joe

  8. Great explanation, as always. I don’t particularly like caramel (please don’t shoot me), but I love making it, because the chemistry of it is just so amazing. I guess the Maillard reaction is right up there with it.

    A separate (but maybe connected) question: I have recently started playing around with baker’s ammonia, aka ammonium carbonate. It does amazing things to a batch of cookies. If it were used in a caramel, or in your recipe above, instead of the baking soda, would it have a similar reaction? (Or would it just kill me?)


    1. It should work in theory, Chana! So long as you simmer the mixture long enough so all the ammonia boils out! 😉

      – Joe

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