Is it possible to change the temperature after a period of time?

For example, an egg where you want to slightly cook the yolk and fully cook the outside.

Yes. You just have to make sure that you keep temperatures within the “safe” zone.

However, in the egg example, you’d need to cool the egg in an ice bath before transitioning to the new temperature. Don’t really know whether this will produce the effect you want. Perhaps cook the yolk slightly then let egg cool off, then break it and dunk it with a rolling motion in simmering water to firm up the whites. Results will vary.

@fpettinati, Why would you need to cool the egg in an ice bath? I’ve never heard that before.

The “perfect soft-boiled egg” according to “Modernist Cuisine” is 1. boiled for 3 minutes, 2. cooled in ice water, 3. cooked in 64C water for 35 minutes, 4. blowtorched for 2 minutes, 5. peeled, 6. reheated to serve at 60C for 30 minutes. I kid you not!

The “Ideas in food” has somewhat easier method of boiling for 5 minutes and 15 seconds, cooling in ice bath, peeling (the blowtorching in the previous recipe was to facilitate peeling) and reheating for 10 minutes at 60C.

Generally, one needs an ice bath to immediately stop cooking processes, otherwise eggs continue to cook themselves. If you serve them immediately, it is of somewhat less concern.

Eggs, unlike many other food items, continue too cook even after equilibrium temperature has been reached. Given this information, it is possible to obtain any combination of yolk/white testures with one time/temperature combination.

Even better news, the good people at ChefSteps have done all the testing and calculating for us!

Check out http://www.chefsteps.com/activities/the-egg-calculator to get a formula for the egg, just the way you want it.

I have only tried this one time so far, but it produced the requested result that time.