Why The Instant Pot Needs Water, by Guy Coburn:
The Instant Pot needs Water, or a watery liquid such as chicken stock or beef broth, EVERY time you
pressure cook. Why? SCIENCE!
How does a pressure cooker work? Water boils at 212°
F (100° C) at normal atmosphere pressure (14.7 lbs psi
at sea level), which is known as "the boiling point of
water." As water converts to steam, it expands. Water
converting to Steam is one of the most important
physics reactions in the world -- it powers all kinds of
things, including most electric generators. It is also es-
sential to cooking.
When that steam is in a closed container, the pressure
in the container goes up. As the pressure increases, the
temperature at which water boils also goes up. (Water
boils at a lower temperature in low pressure, which is
why altitude can affect cooking so much.) In a pressure
cooker, the pressure goes high enough for the boiling point of water to go up to about 250° F (121° C) at
around 11.6 psi over existing air pressure (about 27 lbs psi). It is this higher boiling point that helps food
cook faster and breaks down connective tissues.
Note that if the pressure keeps building while the temperature increases, the pot will eventually ex-
plode. However, our modern pressure cookers have a safety release valve that will relieve the pressure
if it goes too high, and the sensors shut down the heating element if the temperature goes higher than
the under-pressure boiling point. That's why older stove-top pressure cookers used to explode, but
modern electric ones are safe.
WHAT DOES "BURN" MEAN? The Instant Pot has a sensor that detects the temperature at the bottom
of the pot. If the temperature reaches 284° F (140° C), then the Pot will report "burn" and turn off the
heating element. Keep in mind that the Boiling Point of Water is 212° F at regular pressure and 240-250°
F under pressure, so if the Pot reaches 284° F, then something is clearly wrong. Turning off the heating
element will prevent to pot from exploding or further burning the food.
FOR A PRESSURE COOKER TO WORK, THERE MUST BE ENOUGH WATER available to turn to steam in
contact with the heating surface. For the Instant Pot, that is the bottom of the inner liner. If there is not
enough water, the IP will never pressurize. Keep in mind that the Pot is always leaking pressure and
steam, so you need enough water to MAINTAIN the steam pressure. If the Pot reaches Pressure, but
then says "burn," you may not have enough water to sustain pressure, or you may have solids on the
bottom of the pan.
DON'T USE OIL INSTEAD OF WATER; Please NOTE that non-water liquids, like Cooking Oil, will NOT
WORK in a pressure cooker since oil does not convert to Steam when it boils. (It also boils at a much
higher temperature than the Instant Pot will reach.)
HEAVY SAUCES: Any thick sauce, like tomato or barbecue sauce, has a lot of solids suspended in a
water base. These solids have a good chance to burn to the bottom of the pan as the initial water boils
away. The burnt solids then coat some or all of the bottom of the IP liner. The heat from the bottom
continues to burn more of the solids and those solids absorb heat at a higher level than water.
Therefore, the solids cause the bottom of the Pot to reach a higher temperature than the boiling point
of water because the solids insulate the bottom of the pan away from the water it needs to reach pres-
sure. That's why the Instant Pot will report "burn" if there is not enough water or the liquid has too
many solids suspended in it, so those solids get burned to THE BOTTOM OF THE PAN. (Why? We'd
have to go into Thermodynamics and other science-y stuff.) So all those people who get "burn" when
they try to do pasta and sauce? This is why.
MILK OR CREAM SAUCE: Milk may or may not burn, but heavy cream is likely to burn because it has
more solids suspended in water and fat than milk. (Milk and similar dairy is a combination of water,
milk solids and fat all emulsified together.) Sauce made from a thick soup concentrate such as Cream of
Chicken or Cream of Mushroom is likely to burn.
What if you want a thick sauce, like tomato sauce, marinara/spaghetti sauce, barbecue sauce, a cream
sauce or whatever? You need to put the WATER ON THE BOTTOM, LAYER THE THICKER SAUCE ON TOP
and DO NOT MIX THEM (contrary to what you usually do in cooking). Often the best way to do this is
put meat or veggies on the bottom, then pour in Water or Broth, then pasta on top, then layer the thick
sauce on top of the pasta.
If the thicker sauces are layered at the top, with water on the bottom, then enough steam is generated
to avoid the "burn." Most of the time that people get "burn" on their Instant Pot, it is because there was
not enough water on the bottom. That's why you should layer water or broth on the bottom if you are
using a thicker sauce. After it is finished cooking, you can THEN mix up the sauce to blend it. -- if the
sauce is too thin and watery after pressure cooking, you can turn on Sauté with the top open to evapo-
rate some of the water and thicken the sauce or use other thickening techniques
SOME FOODS ABSORB WATER: Pasta, rice and other grains need to absorb water as they cook. You
need enough watery liquid to not only reach and maintain pressure, but also be absorbed into the food.
If all of the water gets absorbed while cooking, you'll likely get a "burn." One key reason to let rice and
other grains have a slow NPR (Natural Pressure Release) is to let them absorb the liquid after cooking as
the Pot cools, allowing the water used to make steam to revert to water and be absorbed.
DEGLAZING THE POT: Another reason why the Pot can report "burn" is if you sauté and do not
"deglaze" the bottom of the Pan. When you sauté (temp over 320° in a dry, conductive heat) the stuff
stuck to the bottom of the pan is called "FOND." The Fond is important to sauces and gravies as holding
a lot of flavor. If you don't remove the Fond from being stuck to the bottom of the pot, it can heat to a
higher temp than the boiling point of water even under pressure. That Fond gets hotter than 284° F,
and you get "burn." So before pressure cooking, you need to "deglaze the Pan" -- which means to add a
small amount of cold liquid (room temp works, but cold is better) to the HOT pan, and this will loosen
the Fond, making it easy to scrape up and dissolve into the liquid. (Use something gentle to scrape up
the Fond, like wood or silicone to avoid scratching the pot.) Wine and broth are commonly used, but you
can use liquor or fruit juice depending on your recipe.
So, for the Instant Pot to act as a pressure cooker (which is most of the time), IT NEEDS WATER ON THE
BOTTOM OF THE LINER!