Purging air from a pressure cooker

Purging air from a pressure cooker - Casting disc of modern car

Many years ago, while instructing me in the use of our pressure cooker, my father told me to always let steam escape from the top stack for a couple of minutes before putting the weighted cap on it. This, he said, would purge air from the cooker and thereby prevent oxygen from attacking the food at the elevated pressure and temperature inside.

This makes a lot of sense to me, but I never see it mentioned in pressure cooking books or instructions. What's the deal?

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Best Answer

In pressure canning, the USDA says:

Air trapped in a pressure canner lowers the temperature obtained for a given pressure (for example, 10 or 15 pounds pressure) and results in underprocessing. To be safe, USDA recommends that all pressure canners must be vented 10 minutes before they are pressurized.

Which might be where your dad borrowed that idea from. The effect in that case is more from the air taking up space that should be filled with steam, and preventing it from being filled with steam (rather, being filled with a steam/air mixture), making the transfer of heat from steam to jars less effective.



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Will my pressure cooker explode?

Can pressure cookers explode? Pressure cookers can explode for many reasons, including being overfilled, using oil improperly, and vents being clogged. These are all preventable reasons by the user. A pressure cooker can also explode due to a malfunctioning or defective part.

How do you release pressure from a pressure cooker?

Open the pressure valve on the lid. Open the pressure valve a little bit to release pressure slowly, or in short bursts 10 seconds apart. Count 10 minutes, and then release remaining pressure by opening the valve. If the pressure dissipates sooner than 10 minutes do not remove lid until time is up.

How do you vent a pressure cooker?

How to Quick Release Instant Pot
  • Wait for the cooking cycle to end.
  • Turn the venting knob from the sealing to venting position. This will quickly release steam. ...
  • Keep the venting knob open. Make sure the steam has stopped flowing and the floating valve has dropped before opening the lid.


    • What happens if you open a pressure cooker?

    So How do you Know When it is Safe to Open a Pressure Cooker? Whenever a liquid under pressure is depressurized suddenly, the gases contained in the liquid (including steam), will expand rapidly. If the proper steps aren't followed, the contents of the pressure cooker can 'explode' when the lid is removed.


    Woman Warns Of Exploding Pressure Cooker After Suffering Severe Burns



    Sources: Stack Exchange - This article follows the attribution requirements of Stack Exchange and is licensed under CC BY-SA 3.0.

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