Molecular structure. Hydrophilic. Hydrophobic. And the science of protein denaturation, simply explained.
I love eggs. If a brunch menu has Eggs Benedict on it, I’ll order it. And I know for a fact that eggs sunny side up can brighten a gloomy day right up. Whichever way we cook them, we know our eggs are ready when the egg white turns… errm… white. This happens because the proteins in the eggs have undergone denaturation (they lose their structure).
Proteins are long chains of amino acids connected by peptide bonds. These long chains form a helix structure that folds back on itself. These long chains have parts that love water and parts that fear water. The parts that love water are called hydrophilic, and they attract water. The parts that fear water are called hydrophobic and repel water.
This structure is stable. But only just. When we heat the proteins, there is just enough energy to break the weak forces that are holding the structure together. The structure not only unfolds, but it also unravels from its helical structure. What results looks more like individual chains.
This is the start of the denaturation process. What happens next is the hydrophilic parts attract water molecules, trapping them. At the same time, the hydrophobic parts link with other hydrophobic parts, forming a larger and larger form-less structure, almost like a fishnet. The combined effect is that of an amorphous 3D-fishnet with trapped water, creating a semisolid gel.
This is the white we see in a cooked egg. The egg white is the result of protein denaturation and is an amorphous semisolid filled with water. That explains the bouncy texture and juicy taste when we eat it.
Denaturation is a very common phenomenon in cooking. It happens with crispy bacon (maybe that’s why bacon and eggs are so yummy), when we make jelly from gelatin (see the 1-Minute NomNom “All set for a jelly good time!“), and when we braise and stew meat (see the 1-Minute NomNoms “Power of braise” and “Are we stew talking about science?“)
Proteins and eggs may fear denaturation because it breaks them down, but for the rest of us, we love the tastes and flavors that it can create.
Don’t fear me. Love me to discover more. All you need is a minute a day to explore the world’s marvels through the phenomenon of food!
photos: in order – depositphotos/mazzzur; electropower; shawn_hempel; coolfonk; Asiorek; si