Consider the absolute miracle that is the egg. It is, without a shadow of doubt, the single most versatile ingredient in the kitchen. This calcium carbonate shell enclosed ovoid ball of 75% water and 25% magic can be scrambled into an unctuous bhurji, pan-fried into a pillowy omelette, whipped with sugar into delicious dessert air, emulsified into mayonnaise, set into ice cream and boiled to every possible combination of texture and mouthfeel. It is the source of a stunning diversity of proteins, even more so than meat or dairy and, in poorer parts of India, one of the most important elements of a mid-day meal for underprivileged children in government schools.
And none of this should be surprising because the egg is designed to turn a single-celled embryo into a feathery, living and breathing baby bird, so it’s pretty overqualified for an omelette in my opinion. And the keyword here is “designed” because, and I say this with exasperation at the general quality of basic science education in India, the eggs you buy from the store will not hatch into a chick. For that to happen, a rooster (the male) has to, and I put it delicately, Netflix and chill with the hen. And there is a global multibillion-dollar egg industry whose singular goal is to prevent roosters from making out with hens. The unfertilized egg is essentially the period of the hen. On the other hand, a cow has to be non-consensually impregnated several times in her life just so that we can exploit the secretions of her mammary glands. And still, it’s dairy products that get the green dot in India while eggs gets red.
I have been waiting a while for some sense to hatch out of this bit of classification logic, but like the eggs I buy from the store, there is no sign of any hatching yet. So, let’s get to the science of this miracle ingredient.
The white and the yolk are made of different kinds of proteins, and crucially, cook at different temperatures. As the temperature reaches 62 degrees Celsius, the egg white turns translucent and starts to set. What’s actually happening here is called denaturation. Proteins are generally large, complex, three-dimensional molecules made up of chains of building blocks called amino acids. As heat is applied, protein molecules lose their three-dimensional shapes and start forming more linear chains that tend to clump together. This is why almost all proteins get tougher in terms of texture when heated. Raw meat, for instance, has a softer and elastic feel while cooked meat is tougher and chewier.
As the temperature increases to 68 degrees Celsius, the yolk proteins will start setting and the whites will start turning opaque. As they denature, the runny yolk takes on a soft and waxy texture at the start, and if you continue applying heat, it will turn into the crumbly texture that we are familiar with from hard-boiled eggs. With more heat, the whites will start generating some hydrogen sulphide gas, a smell that we tend to associate with overcooked eggs and kala namak. So, if you don’t overcook your eggs, they will not smell “eggy”! If you continue cooking past this point, the hydrogen sulphide gas will react with the iron present in the yolk to form ferrous sulphide, which is green in colour and gets deposited between the whites and the yolk of a terribly over-boiled egg.
Now that you know all this science, here is how you can use it to boil eggs consistently every time. For starters, to boil an egg perfectly, don’t boil it. Steam it instead. Steaming is significantly gentler on the egg and because water vapour transfers heat at a slower pace than liquid water, the risks of overcooking are significantly minimized. As for timing, you will have to test it yourself so that you get the texture you like.
When you are making an omelette, another science trick you can use is to break the egg into a bowl and add a pinch of salt and let it sit for at least 15 minutes. Salt uncoils the proteins ahead of time so that when you actually cook the omelette, the proteins will set into a softer and creamier texture because the uncoiled proteins will take more time to set. Another trick here is to use frozen or really cold butter. This way, the water in the butter needs more time to turn into vapour and results in a creamier and fluffier omelette.
But if you are making an omelette as part of a gravy dish, then you want it to be ultra-fluffy and airy so that it can absorb the flavours in the gravy. To do this, we take advantage of the diversity of proteins in the egg. We separate the whites and the yolk and whisk the whites till they turn into an airy foam. Then we add the yolk mixture back in and gently fold it into the foam and then bake it in an oven at 170 degrees Celsius for about 15 minutes. This will get you an omelette with the texture of a sponge cake that will soak up the juices in your gravy. As the J.R.R. Tolkien riddle goes—An egg is a box without hinges, key or lid, yet golden treasure inside is hid.
Masala Lab is a fortnightly column on practical food science in the Indian kitchen. Krish Ashok is the author of Masala Lab: The Science Of Indian Cooking, which will be published in December.