Pressure Canning 101

This page is not intended to be a complete guide to pressure canning or take the place of thoroughly reading your pressure canner's manual.  What it is intended to do is provide some visuals and explanations of the basics of pressure canning, and to ease some of the uncertainty that can be associated with this method of preservation.  So, let's get started...

Why a pressure canner? 

Not all foods are suited for preservation in a boiling water bath canner.  That method is only appropriate for foods with high levels of acidity and low acid foods being preserved through pickling which contributes enough vinegar to ensure safe canning.  Low acid foods such as vegetables and meats cannot be safely canned using this method because a boiling water bath does not reach sufficient temperatures to kill botulinum spores.  Since botulinum bacteria  require moist, low acid foods at temperatures often present in our homes and can only grow in the absence of oxygen, a canning jar is the perfect home for them.  Therefore, it is necessary to use a pressure canner to preserve these foods since a pressure canner can reach much higher temperatures than other methods thereby killing the spores.  You can also can high acid foods in a pressure canner, but the result may be softer end products due to these higher temperatures.

What equipment will I need?

The equipment needed for pressure canning is the same as for water bath canning except that you will need a pressure canner rather than a boiling water canner.  The pressure canner comes small flat rack for the bottom. 

What types of pressure canners are out there?

There are two main types of pressure canners.  A weighted gauge pressure canner relies on a weight that jiggles to indicate the amount of pressure present.  Dial gauges have a numbered dial instrument on top which indicates the amount of pressure present.  Either one is fine, but a dial gauge canner removes the guessing game often associated with the weighted gauge and is generally viewed as the more user-friendly of the two.  I use a dial gauge pressure canner.  If using a dial gauge canner, contact your local Cooperative Extension service at the start of canning season to get your dial tested for accuracy.  They will do it for free.



This is the Presto canner I have.  It only holds one layer of jars, but some are larger and can hold two layers.  Notice its dial gauge on top. 
http://www.gopresto.com/products/products.php?stock=01755

What are the basic steps of pressure canning?

The following steps are for a dial gauge canner.  Before beginning to use your pressure canner, you will want to read the manual and assemble it according to the manufacturer's directions.

1.  The first thing you will want to do is wash and sterilize your jars just as you would for water bath canning.  You can do this in a dishwasher or a pot of boiling water.  You will also need to soak your lids in a pot of hot water to loosen the rubber. 

2.  Begin preparing your food as directed in the recipe you are using.

3.  Place your pressure canning pot on the stove and add 3 quarts of water.  When pressure canning, it is not necessary that the water cover the jars.  Place your jars in the canner (filling them with a little water to hold them down) to keep them warm until you are ready to fill them with food.  Turn the stove on to begin heating the water while you finish preparing the food.

You cannot tell very well here, but the water comes up about 2 inches on the outside of the jars. 



The jars will remain in the canner as the water in the bottom comes to a boil.  This will keep your sterilized jars warm.  The jars sit on a flat rack with holes which comes with your canner.

4.  Fill your jars with prepared food, and place sterilized lids and rings on top.  Place the jars in the canner. 

Jars going into the canner just before the lid is put in place

5.  Place the lid on the canner and rotate it according to your canner's directions to make sure it is closed completely. 

When the lid is on correctly, the handles will be aligned and the lid will not rotate further.

6.  Heat the canner until a steady flow of steam can be seen leaving the vent pipe. 

You cannot see the steam in the picture, but there was a steady flow rising from the vent pipe (the little tube sticking up to the right of the dial).

7.  This step is very important.  Once you see steady steam escaping the vent pipe, begin timing.  You will want to allow the steam to continue to escape for 10 minutes.  This exhausts air from the canner and is an essential step.

8.  After ten minutes, place the pressure regulator over the vent pipe.  Continue heating the canner.

In the picture above, the pressure regulator (the metal cylinder with the black cap) has been placed over the vent pipe which prevents steam from escaping further.

 9.  In just a few minutes, pressure will begin to build inside the canner.  You will know there is pressure in the pot when the cover lock rises and locks in place (at least that is what happens on my canner).  In the picture below it is the round metal piece at the front of the lid.  Notice that it is sticking up about 1/2 inch above the lid unlike in the picture above when it was flat against it.

In this picture, the cover lock (the round piece on the left) has risen indicating the presence of pressure, and the dial gauge registers 11 pounds of pressure.  At this point, timing can begin.

10.  Watch the dial gauge until it registers 11 pounds of pressure.  If you live at higher altitudes, you will need to adjust the pounds of pressure based on your elevation.  Visit National Center for Home Food Preservation for more on this.

11.  Once the correct pressure is reached, begin timing your processing according to the recipe you are preparing.  You may need to adjust the heat of the stove to maintain the correct pressure, but make sure that the pressure does not drop below the designated amount necessary. 

12.  After the processing time is complete, turn the burner off but do not remove the lid at this point.  Allow the pressure to drop on its own which can take some time.  You will know the pressure in the canner is zero when the cover lock drops and no steam leaves the vent pipe.  Do not rely solely on the dial gauge to determine this.

You will know pressure is reduced completely when the dial gauge reads zero, the cover lock (round piece in the front) is down, and no steam escapes from the pressure regulator when it is jiggled slightly.

13.  Once the pressure has completely dropped (the cover vent is flat on the lid like in the picture below and the dial is zero), remove the pressure regulator from the vent pipe and allow the canner to sit undisturbed another 10 minutes.

The pressure regulartor has been removed to expose the vent pipe once again.  At this point, the canner sits a few more minutes before the lid is removed.

14.  Carefully remove the lid (away from you so that you don't get burned).  Remove the jars to a towel to cool completely on their own.  They will probably be bubbling at this point, and you may see a slight amount of seepage from the jars due to pressure.  This is completely normal and nothing to worry about.

You can see the liquid inside the jars continuing to boil and bubble after they are removed.  Once they have cooled and sealed completely, these bubbles will subside, and the jars can be rotated gently to redistribute the contents.

15.  That's it!  You used your canner successfully.  Now clean it and store it until you are ready to can again.