Thickness of Whites

Thin older whites whip more easily to a higher volume than thick, fresh ones. But once whipped, the foam from thin whites is less stable, because the liquid film drains more easily from the bubbles. If volume is more important than stability, older eggs are better.

For the most part, however, eggs purchased through normal channels have already aged, sometimes by several weeks. For better stability, a good rule of thumb is to use fresher eggs for meringues, saving older ones for general baking.