science of foam formation

• foaming denatures the proteins, causing the food to become light and airy
• the action of the whisking causes the protein bonds to break and causes the protein to unfold
• the denatured protein molecules then start to join up with other denatured protein molecules (coagulation)
• this traps the air bubbles and holds it in place, forming a foam
• under-whisked egg white and cream become unstable and cannot hold the required shape
• over-whisked egg white makes the coagulated protein molecules bond too tightly, squeezing all the water out, forming a watery mixture
• over-whisked cream 'splits' because the fat globules clump together, forming butter