Pressure Cooker Basics

Chicken with mushrooms sauce
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The pressure cooker is a kitchen device that many of us remember from watching our grandmothers or mothers cook—that mysterious large pot or cauldron with the tightly sealed lid and whistling vent on top. After being somewhat absent for quite a while, due partially to the public's temporary infatuation with microwave ovens and slow cookers, the pressure cooker has now returned as a modern tool for busy cooks.

How Pressure Cooking Works

The advantage of pressure cooking lies in simple physics. By confining pressure inside the pot, the boiling point of liquids is increased from 212 degrees F. to as high as 250 degrees F. For example, a pot at sea level without a cover on it boils at 212 degrees F, and the steam evaporating from the pot is also at 212 degrees. But if a sealed cover is put on the pot to trap the steam, the pressure inside the pot increases, which causes the boiling point of the liquid (and of the steam released) to also rise. In a pot with 15 PSI (pounds per square inch) of internal pressure, the temperature of the boiling water and steam can be as high as 250 degrees F. This means that foods cooking inside the pot can be cooked 3 to 10 times faster than when they are cooked uncovered.

Anatomy of a Pressure Cooker

The basic design of a pressure cooker has been largely the same for many years. It consists of a pot or caulron with a locking lid that has a tight seal to confine the pressure inside the pot. A valve on top of the lid offers a means of controlling the amount of pressure that can build up inside the pot. In old-style pressure cookers, the valve on the lid was covered with a weighted fitting that rattled and hissed mysteriously when the pressure inside the pot grew high enough to lift the weight and push steam out of the vent. These cookers were sometimes called "jiggle-top" cookers. This rudimentary vent provided the safety release, and unwary hands might easily get burned if they tried to lift off the weight before the contents lost their pressure. Most classic pressure cookers had some form of "over-pressure" plug designed to pop up when the pressure inside the pot grew dangerously high.

Foods are usually placed inside a wire basket that fits inside the pressure cooker, suspended over the cooking liquid providing the steam. Depending on the recipe, the foods may be submerged in the water or suspended above the water and cooked by steam alone.

Modern pressure cookers have pressure-release systems designed to make them absolutely safe. The pressure controls and release mechanism are fitted into the handles, making it very easy to adjust the pressure and to release it when cooking is completed. Rather than a weighted "jiggle-top" vent, a spring-loaded vent system is used in newer pressure cookers. Newer pots may also have visual safety signals that alert you to dangerously high pressure. With modern pressure cookers, there is little chance of rupture, as did happen on rare occasion with the old-style pressure cookers your grandmother and her friends used.

Modern pressure cookers are quite sophisticated in their features. For example, some models are programmable, and can be used as slow cookers, warmers, and yogurt makers as well as pressure cookers.

Meal Preparation With a Pressure Cooker

Preparing foods in a pressure cooker isn't hard, but it does require some specialized techniques and different steps. And the recipes used either need to be designed for pressure cookers or adapted in a way that makes them suitable for this style of cooking.

  1. Check the pressure cooker pot and lid to make sure it is free of dents and cracks. Because they cook under high pressure, pressure cookers can be susceptible to damage. Any cooker that has been dropped should be carefully examined for damage.
  2. Add water or liquid to the cooker, according to the recipe. Some kind of liquid that can boil must always be used in the cooker; usually, recipes call for water. Never fill the cooker more than 2/3 full of liquid, since there needs to be room for steam to be emitted. Older jiggle-top cookers need at least 1 cup of water in the pot; spring-valve-style cookers need at least 1/2 cup.
  3. Prepare the food in whatever manner is called for by the recipe. This means, at the very least, fully washing it. Frozen foods must be completely thawed. Red meats and poultry are best seasoned and browned before they are pressure-cooked.
  4. Place the food in the basket, and place it inside the cooker. Open the pressure regulator (or remove the jiggle weight), then attach the lid and lock it into place. Apply full heat to the pot.
  1. When steam begins to emerge from the vent, set the jiggle weight or close the safety valve. Newer pressure-cookers may have a color-coded signal on the handle that tells you when it is time to close the valve.
  2. Reduce the heat so that the contents continue to simmer and boil. If the temperature is too hot and the pressure too high, the safety valve may begin to whistle, which is your signal to turn down the heat slightly.
  3. When the food has cooked for whatever period is called for by the recipe, turn off the heat and allow the pressure to subside. This can take 15 to 30 minutes if you simply wait for the contents to cool, or you can quickly release the pressure by activating a quick-release button, if your pressure cooker is equipped with one. Yet another way to drop the pressure quickly is by running cool water over the pot (never do this with an electric pressure cooker).
  4. Check to make sure all pressure is released, either by removing the weighted jiggle valve or by moving the valve stem to the open position. If no pressure hisses out, you can now remove the lid and remove the food.

    Browning Food in the Pressure Cooker

    When it's called for, foods can be browned right in most pressure cookers. For an old-fashion-type pressure cooker, place the cooker on medium-high heat and brown the foods. Then add liquids and remaining ingredients, cover, bring pressure up, and complete the pressure cooking. For newer cookers, most have a brown function—see manufacturer's instructions.

    Safety Tips

    Although quite safe if used properly, there is some risk with pressure cookers. Follow these tips to minimize the possibility of mishaps:

    • Follow the instruction manual. Each type of cooker has its own procedure for safe use, so make sure you understand and follow the manufacturer's advice. This is a good reason not to buy a pressure cooker at a garage sale or flea market that doesn't have its instruction manual included. If you have an older cooker, learn show to do a pressure cooker hot water test to familiarize yourself with it.
    • The rubber gasket seal and the steam vent tube are the critical parts of this appliance, so make sure that the gaskets are solid, clean, not ripped or torn, and that the vent tube is clean and clear, not clogged with food. Use the cleaning implement that comes with your pressure cooker or a pipe cleaner to keep that vent tube clear.
    • Be very careful following instructions about attaching the lid securely, quickly reducing steam pressure, and opening the pot when cooking is completed.
    • Keep an eye on the pressure indicator rod. When the pressure cooker is cooking, the rod should be in the raised position (or jiggling, on older models). If it is not, there may not be enough liquid in the cooker to convert to steam and the food can burn. Stop the cooker according to the manufacturer's instructions, and when the pressure goes down, lift the lid and add liquid.
    • Think twice about leaving a pressure cooker alone while it's cooking. Never let children or pets play around the appliance when it's cooking.
    • To open the lid when cooking is done, you must release the steam from the pressure cooker first. Be very careful when you release pressure; you can burn yourself even with the new cookers that have safety releases. If you use the quick release features, make sure to release steam in very short bursts (like the pulse feature on your food processor). If you hold the release button open, hot liquid may spurt through the valve and burn you. Never try to force the lid open.
    • Watch out for foods that foam. Dried beans, pasta, and some fruits (especially apples) can create foam when they cook, and small particles can ride up on that foam and clog the steam vent. Fill the pressure cooker no more than half full when cooking these foods, and add a tablespoon of oil to keep the foam to a minimum. Foods that cause the most problems with foaming include split peas and beans, oatmeal, apples, cranberries, and pearl barley.
    • Do not use your pressure cooker as a deep fryer, filling it full of cooking oil, unless it is specifically marketed as a fryer.

    Adapting Recipes for Pressure Cooking

    Timing is critical when you're pressure cooking. Foods such large pieces of meat have a bit of "wiggle room" in timing, but fresh vegetables and fruits can be quickly overcooked in a pressure cooker, which turns them to mush. If your pressure cooker doesn't have a built-in timer, make sure you have a reliable, accurate timer that you use every time you pressure cook. Use whatever cooking time charts are provided by the manufacturer of your cooker.

    If you're adapting a conventional stovetop recipe to pressure cooking, set the timer to 1/3 of the cooking time called for by the original recipe. For example, if a recipe calls for cooking on the stovetop for 1 hour, cook for only about 20 minutes in the pressure cooker, then release the steam following the manufacturer's directions, and test the food for doneness. You can refasten the lid and cook for 1 to 3 minutes longer if the food needs it. It's best to undercook food until you're sure of the pressure cooker and recipes; you can always put the appliance back together and cook a little longer if necessary.

    Many crockpot recipes convert easily to the pressure cooker. Cheaper cuts of meat, such as brisket and chuck, are cooked to perfection in the pressure cooker, but the cooking time is greatly reduced. A recipe that cooks for 8 to 10 hours on low heat in a crockpot usually requires only about 1 hour in a pressure cooker.

    Many pressure cooker recipes call for foods that have the same cooking times; beef and potatoes, or chicken with parsnips, for example. With other recipes, you can use an interrupted cooking method, as in this recipe for Crockpot Chicken Alfredo, releasing the lid and adding other ingredients as the cooking time reaches a few minutes. When you use this method, be sure to write down the times when the more fragile ingredients are added, and carry that timer along if you leave the kitchen.

    Storing Your Pressure Cooker

    Don't store your pressure cooker closed with the lid on—that will just allow aromas to stay in the cooker, and molds and off-flavors can develop. Sprinkle a bit of baking soda inside the cooker when you store it to prevent these problems. Store the lid separately from the base. Also, do not store the rubber gasket in the base.

    Some Favorite Recipes for Pressure Cookers