Reader Jay writes:
When you were talking about macarons, you said that old egg whites are better. Does the rule hold true for floating islands?
It does. Older eggs are better when it comes to making any sort of foam. Why? Simply because older eggs have runnier whites, and when egg whites are runny it’s easier to put the hurt on the proteins they contain. Think of it like this: a whip cuts through a bowl of water with much more force than it does through a bowl of, say, honey. The result is that older whites are not only easier to whip, they whip up higher.
The only problem with old eggs is that the yolk walls are thinner and so are more likely to rupture when you separate them, getting unwanted fat in your whites. The best way to prevent this from happening is to separate your eggs right when you take them out of the refrigerator, then let the whites warm to room temperature before you whip them.