CLAIRE HILL
WHY ARE EGGS SO USEFUL IN BAKING, AND ARE THERE ANY SUBSTITUTES?
Eggs contain over 40 different proteins, which hold the key to their culinary success. The long protein molecules fold and coil so that waterhating (hydrophobic) sections are tucked safely away. Loose bonds hold each protein molecule in a tight unit, but heat or whisking causes the chains to unwind or denature. This allows different proteins to link their hydrophobic regions together and form a strengthening 3D network. The coagulation is irreversible and transforms eggs into a semi-solid or solid state. Whisking egg whites unravels proteins and adds air bubbles. The proteins link together and collect at the surface of the bubbles to hide their newly exposed hydrophobic parts from water in the egg white. The proteins prevent the air bubbles from popping, even during cooking. In baking, egg proteins combine with wheat proteins in flour to form a strong network of trapped air bubbles that can expand in the oven.