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.