Why is it best to use fresh eggs at room temperature when making a sponge cake?

When making a sponge cake, the eggs are stirred with sugar to increase their volume and brighten them, resulting in the characteristics of this wonderful cake being finely divided and light in texture. Fresh room temperature eggs are best for sponge making, but why?

Essentially, eggs are acidic when fresh, and this acidity causes the proteins in white to bind tightly together. As the egg gets older, it becomes more alkaline, and the proteins begin to pull apart from each other, causing the white to become thinner.

Now, when you stir the protein, you actually separate the proteins and then recombine them into a new structure around the small bubbles to form a foam. With fresh eggs, it is a bit difficult to initially separate these tightly bound proteins, and stirring takes longer. But the resulting foam will make the older eggs more stable.

Therefore, in order to offset the extra time required for fresh eggs to stir the foam, you can use a room temperature that is easier and faster to convert than frozen eggs.

So, for fresh eggs at room temperature, you get the best of both worlds - a stable foam/mixture that doesn't take long to reach the desired consistency. So when making any recipe based on stirring egg whites or whole eggs, including souffle, meringue mixture and some cakes, such as sponges, choose the freshest eggs, you can get your hands and make sure they are at room temperature .