Together with our friends from "Physics for Everyone", we're diving into the world of coffee — the scientific way!

Take a bite of a warm croissant, and you'll instantly hear the crunch of its thin crust, with a soft, airy center hiding just beneath...
How does the same pastry manage to be so different on the outside and inside at once?

The whole secret lies in the fact that, during baking, its layers heat up and lose moisture at different rates!

The surface comes into direct contact with the hot air. Water evaporates from it quickly, so the outer layer becomes dry and firm. Once little moisture remains, the crust's temperature can climb above 100 °C, triggering reactions that create a golden color, rich aroma, and flavor. The dry structure breaks easily (and there's that crunch so many people love).

Inside, though, things happen quite differently. Moisture evaporates more slowly and holds the temperature near the boiling point of water for a long time. The starch absorbs water and swells, proteins set the shape, and gas bubbles in the dough preserve its porous structure.
That's why the center stays moist, springy, and soft.

Once it cools, the contrast gradually fades: moisture from the center migrates to the crust, softening it.
That's why pastries are best eaten right away, while the crust stays fresh and pleasantly crispy!