Eggs with copper
I had pretty much given up on using a copper bowl for whipping egg whites long before I even started to cook seriously – it never seemed to make a difference in the way the whites whipped, or how long it took.
Turns out I was misinformed – the copper isn’t supposed to do anything for the whites as they’re whipping, but it reinforces the foam and gives you two important characteristics. Firstly, the foam lasts longer, so you have a little more leeway to do what you’re going to do with them before it starts to sag. Secondly, it stabilizes the foam matrix as it cooks, giving you more rise and firmness in the final product.
Yesterday, I took another stab at the pudding cakes, this time with a newly purchased copper bowl, and the texture difference in the cakes with copper was striking.
If you buy a copper bowl, remember that they almost always come with a coating of laquer (keeps it shiny in the store) that needs to be removed with nasty chemicals and steel wool before you use it the first time.