Saturday, August 11, 2012

Pressure Canning Tomatoes

Now that the tomatoes in my garden are finally getting ripe it's time to start canning them.  I try to can them the day I pick them for the best results.  Obviously, that's not always possible, but I try.

When planning on how many jars you will need based on tomato volume figure 7 large tomatoes will fill one quart jar.

Besides the tomatoes the only other ingredients you will need is lemon juice and salt.  Salt is optional but make sure you don't use iodized table salt . . . you want a salt that doesn't have added ingredients.  

Equipment you will need:

Pressure Canner (I use an AllAmerican model 915). An excellent canner, by the way!
Pint or quart canning jars (quart jars are more economical)
Large spoons and ladles
Lids and Rings
Jar grabber (to pick up the hot jars)
Lid lifter
1 large pot for scalding the tomatoes
1 small pot to sanitize the lids.
Jar funnel

Be sure to sanitize the jars, this removes any fungus and bacteria to prevent spoilage.  You can use the dishwasher for this if you have an extra hot or sanitize cycle, but you can boil them in the canner while your prepping your tomatoes, which is what I usually do.

If you're using the canner, fill the jars with water and place them in the canner.  Then fill the canner with water  until it is over the tops of the jars and bring to a boil.  You will only need about 3 inches of water for the actual canning process but you can dump out the excess water before you put in your filled jars.

Otherwise, fill the canner about half full and bring to a boil.

Put the lids into the small pot of boiling water for at least several minutes.

Bring a large pot of water to a boil.  Put the tomatoes, a few at a time in the boiling water for no more than 1 minute (30 - 45 seconds is usually enough) and them put them into a large bowl of ice water.  This will make removing the skins ridiculously easy.

You want to use the freshest tomatoes you can; preferably unbruised and blemish free but that's in an ideal world.  Just be sure to cut out any bruised and discolored flesh when chopping them for the jars.  You definitely do NOT want rotten or mushy tomatoes!

Once you've removed the skins, cut the tomatoes in halves or quarters . . . making sure to remove any tough, bruised or soft parts.

Fill the sanitized jars withing a 1/4 inch of the top with the tomatoes. After the jar is filled, add 2 tablespoons of lemon juice per quart jar, 1 per pint jar.  This helps to reduce the odds of spoilage and to retain color and flavor. Then fill to 1/2 inch of the top with either boiling water or boiling tomato juice.  Add a pinch of salt, if desired.

Release any trapped air bubbles by sliding a flat utensil up and down around the inside edge of the jars.

Wipe the lips of the jar with a clean dry cloth or paper towel. Then put the lids and rings on.  Screw on the rings finger tight only.

Dump out any excess water out of the canner leaving about 3 inches of boiling water.  Put the jars in the pressure canner.  Then put the lid on and screw it down.

Let the canner vent steam for 10 minutes before putting the weight on.  After venting put the weight on and let the canner build pressure.

For a weighted canner, like mine, process both pints and quarts for 15 minutes at 5 pounds of pressure.  Make sure you read the instructions for YOUR canner before using it.

When the processing time is up.  Vent the canner and remove from the heat.  DO NOT remove the lid until the pressure is down to zero.

Lift the jars out of the water and let them cool without touching or bumping them in a draft-free place (usually takes overnight).  I normally let them sit for at least 12 hours.   You can then remove the rings if you like to reuse.

Once the jars are cool, you can check that they are sealed verifying that the lid has been sucked down. Just press in the center, gently, with your finger. If it pops up and down (often making a popping sound), it is not sealed. If you put the jar in the refrigerator right away, you can still use it.

Personally, I don't recommend reprocessing the jars if they haven't sealed because to tomatoes will be smooshy.

The tomatoes will float over the liquid.  This is normal, so don't panic.  You can reduce the amount of liquid in the jar by packing the tomatoes tighter next time.  But, remember, tomatoes are mostly water so you'll always get that water layer.

Finally, store them in a cool, dark place.  Enjoy them all year!


  1. hi I have a AA pressure canner and I canned some tomatoes for the first time 10 lbs for 15 mins. my head scace was 1/2 inch I lost a lot of water after they processed what did I do wrong. the jars did seal.

    1. • Jars were packed too solidly with food or were overfilled. Allow 1/2-inch headspace for all fruits and tomatoes, and 1-inch headspace for vegetables, meat, poultry, and seafood. This is necessary since food expands during canning.
      • Exhaust period was insufficient.
      • Pressure regulator on the weighted gauge canner rocked vigorously during processing. Always maintain a slow, steady rocking motion.
      • An unsteady heat source or steam leakage caused a fluctuation of pressure during processing.
      • Removing or bumping the pressure regulator before pressure has completely dropped. Pressure should always drop of its own accord.
      • Uneven pressure from rapid temperature changes or drafts blowing on the canner.
      • Lids were not adjusted according to manufacturer’s directions.
      • Failure to precook food before packing in jars thus allowing shrinkage to occur in the jar. It is especially important to preheat fruit.
      • Failure to allow the canner to remain closed for 10 minutes after pressure has completely dropped.