Reader Kitty writes:
So the whole putting a can of condensed milk in a pan of boiling water thing makes caramel because of the pressure cooking and thus shortens the time? Or perhaps they are a bit more base as well… hmmm.
Hey Kitty! It depends on the technique you use to make dulce de leche. If you do it the old-fashioned way by simply simmering milk and sugar for an hour or so, you get Maillard-type browning initially, and then caramelization. If you boil a can of sweetened condensed milk in a saucepan, you just get caramelization.
I know what you’re thinking: Hang on a second Joe, doesn’t it take a lot more heat to create caramelization…like 300 degrees Fahrenheit or more? Boiling water can only reach 212 or so before it turns to steam. What gives?
Well I’ll tell you. It’s true that sugar can’t caramelize at the temperature of boiling water. However there’s an area of a pan of boiling water where the temperature greatly exceeds 212 degrees Fahrenheit: the bottom. It’s sitting right on top of the heat source. When you insert a can of sweetened condensed milk into that pan, the bottom of the can is in direct contact with the bottom of the pan, which is sitting right on top of the heat source. Down there, temperatures get up over 300, and that causes the sugars in the lower part of the can of sweetened condensed milk to caramelize.
So really, it’s not the boiling water that’s creating the caramel. In fact the boiling water is actually cooling the can so it doesn’t blow up. The method works most of the time…though not all of the time. Sometimes people boil the can for so long that the water level drops and exposes the can. Other times you get steam buildup and an explosion all the same. Either way the result is a shower of boiling water and caramel for whomever is standing in the kitchen at the time. And zis, she iz no good.
Some folks get around these dangers by poking holes in the top of the can to relieve the pressure. They then fill the pot only to the lip of the can. That’s probably a better solution, but still not something I’d ever recommend. The best method I know of for converting sweetened condensed milk into caramel is to open the can and pour it out into a baking dish, then place the dish in a water bath and bake it in a 400+ oven. This way you get good caramelization of the surface while the pan stays cool enough so the caramel won’t burn. Having done it, I can say that it works.
The problem for me is that no matter which method you use for caramelizing sweetened condensed milk, your raw material is still sweetened condensed milk, and that produces a vastly inferior dulce de leche, at least in my view. The simmering method allows you to mix your milks, get creative with your sugars, add spices, whatever you like. And it doesn’t take a whole lot more time.