What are the best egg substitutes for baking? | BBC Science Focus Magazine

Eggs contain over 40 different proteins, which hold the key to their culinary success.

• Heat or whisking causes irreversible coagulation and transforms eggs into semi-solid or solid states.
• When egg whites are whisked, it unravels proteins and adds air bubbles. The proteins collect at the surface of the bubbles, preventing the air bubbles from popping, even during cooking.
• Egg yolk contains an emulsifier called lecithin that keeps oil droplets dispersed in water, preventing them from separating.

It is difficult to find a complete substitute for eggs.

Egg emulsifiers are the easiest to replace, such as soy lecithin as a substitute. Flax or chia seeds, bananas or mustard can also be used to stabilise emulsion droplets. 

Eggs as thickeners are harder to replace, although ground flax or chia seed can work well in cookies or muffins.