The Science of Whipping Egg Whites
Whisking egg whites and watching them go from a mostly clear liquid to a white foam is always so fascinating. But what is happening to cause that transformation? This post will go over the science behind whipping egg whites as well as give you some tips and tricks to help the process along.
What are egg whites?
Egg whites, also called albumen, make up about two-thirds of an egg, with the primary purpose of protecting the embryo. They are made up of 90% water and 10% protein. This protein is what provides the structure while whipping.
The Stages of Whipping Egg Whites
Whisking egg whites both adds air and unravels and rearranges the protein structure. The egg whites will look and behave differently at different stages of whisking
Shortly after you begin whisking, the egg whites will appear bubbly and foamy as air bubbles begin to be trapped by the protein. This happens because part of the protein likes to be near water (hydrophilic) and part likes to avoid water (hydrophobic). This causes the protein to create a boundary between the water and air, stabilizing the air bubbles.
As you continue to whisk, you continue to add air and further unravel the protein structure, resulting in more stable bubbles. Eventually, you will notice that the egg whites lose their transparency and become white and fluffy. The whisk will start to leave trails and the eggs whites will be able to hold their shape briefly before folding back on themselves. This is the soft peak stage.
Finally, more whisking will bring the egg whites to stiff peak stage. The protein-air bubble structures are strong enough to support themselves and the whipped egg whites can hold their shape. The final product can be up to 8 times the volume of the starting egg whites!
Tips for Successfully Whipping Egg Whites
Here are some tips and tricks to successfully whip your egg whites every time:
Use aged egg whites. Aging egg whites causes water to evaporate leaving a stronger protein structure. You can age egg whites by refrigerating them for a day or two in a bowl covered with plastic wrap with small slits cut into it.
Bring aged egg whites to room temperature before whisking. This reduces the surface tension and allows for more volume.
Whisk in a clean and dry bowl. Any residual water, grease, or soap can interfere with the protein bonding necessary for building the foamy structure.
Stabilizers, such as cream or tartar, are often added to help the egg whites maintain their structure. Other acidic ingredients such as vinegar or lemon juice can also be used.
Looking for a way to test your new knowledge of whipping egg whites? Try this Pumpkin Spice Macaron recipe that requires stiff peak egg whites to make the light and airy shells.
