A WISE MAN once said, “Pressure: Pushing down on me,pressing down on you.” The point being, pressure sucks—that is, unless you’re cooking with pressure. Because while pressure cooking might seem terrifying, in the sense that it’s a great way to vaporize food and half your kitchen, if you do it right, it’s also a great way to prepare food with incredible speed. Why? Because physics, that’s why.
Whenever you boil water you’re pushing that liquid to 100 degrees Celsius, tops. In a pressure cooker, though, water temperature can soar to nearly 120 degrees. That’s because the molecules in the steam are getting really excited, bouncing around with higher and higher velocities as the temperature climbs. If you’re boiling in a normal pot, excited molecules are escaping as steam. But in a pressure cooker, that steam has nowhere to go. That means it’s all the while making contact with the boiling water, heating the liquid way past 100 degrees.
You know how water tends to boil quicker at higher altitudes? Well, that’s all about pressure too. At higher altitudes, you’ve got fewer air molecules bearing down on you. That means lower pressure up in the Rockies than down at the beach. And for water to turn to steam, the vapor pressure needs to reach that of the surrounding air pressure. Therefore, when air pressure is lower, water boils quicker because it has a lower bar to meet. (That’s an accidental pressure pun there, people.)
Anyway, back to the pressure cooker. What does its extreme heat get you? It means you not only cook faster, butexponentially faster, as our friends at ChefSteps point out. Raise the temperature just 5 degrees above the normal boiling point of 100 degrees Celsius and you cut your cooking time in half. Another 5 degrees and you halve it again. Get to the max of 120 degrees and you’ll be cooking at 16 times the normal speed.
What’s happening is the pressure cooker isn’t only heating the liquid that naturally appears inside the food. It’s forcing steam through the grub as well, and steam simultaneously cooks it and keeps it hydrated. As an added bonus, the extreme pressure tends to keep food together instead ofpulverizing it.
By pressure cooking, you’re using physics to open up a whole new culinary world—moist meats, tough foods like beans that untoughen right quick, onions caramelized in a flash. So maybe pressure ain’t such a bad thing at all. Maybe it isn’t something that brings a building down, splits a family in two, puts people on streets. Unless, that is, you don’t read the damn instructions.
source: wired.com by