Canning is sometimes intimidating to first-timers because of the potential for "doing it wrong" or losing pounds of valuable tomatoes to spoilage. Also, home canning is somewhat time consuming, which can turn many off the idea. However, the hook comes in January when you look at your pantry shelf, full with quart jars of juicy farm tomatoes. When you open a jar on a cold winter's day and realize that you can't buy anything nearly as nice in stores, the willingness to can more tomatoes the next summer somehow appears. Canning is generally more enjoyable when you have someone to help with the processing. So invite a friend over, put on your favorite music, and think about those lovely soups you will be enjoying the next winter.
This post is a simple photographic how-to on basic processing and canning techniques for raw-packed heirloom tomatoes, though there are multitudes of recipes available online and in canning books. Tomatoes and jams are easily canned in water-bath canners. There are a few steps that are different for pressure canning and water bath canning. Pressure canners can be used as water bath canners, but they also allow the flexibility to can a large variety of other foods that require more sophisticated preserving methods. For basic preservation of tomatoes, however, this recipe is as simple as it gets. The end result provides soft chunks of tomatoes in their own juices. Heirloom tomatoes have more water than other varieties, but the flavors are superb. The "water" or juices are valuable for making sauces and soups more delicious.
About 20-30 lbs of heirloom or slicing tomatoes
Citric acid (found with canning supplies), or bottled lemon juice
Canning and pickling salt (dissolves faster, but any salt will work)
Pressure canner or water-bath canner (or a large stock pot that is tall enough for jars to sit inside with 1/2 inch of water covering the jars).
Several quarts of boiling water
2 Tbs white vinegar
Wide mouth canning funnel
A long handled plastic or wooden mixing spoon, spatula, or cocktail muddler
7 quart size Mason jars with lids and bands (wide or narrow mouth)
A small saucepan with boiling water (for sterilizing lids)
A magnetic lid lifter (optional, found with canning supplies)
Dishwasher or boiling water for sterilizing and heating Mason jars
Clean dish rags and towels
For processing tomatoes:
A cutting board set inside a raised-edge baking sheet
A sharp knife
A large stock pot with boiling water for blanching
About 1 gallon of ice
Large spoons or sieves with handles for lifting whole tomatoes out of blanching pot
Several large bowls or trays for holding tomatoes at different stages
1) Boil a large pot of water for blanching the tomatoes (to remove skins). And in a small pan, boil water for sterilizing the lids. Boil the lids for at least 10 minutes, and leave them in hot water until ready to use.
Wash the Mason jars in a dishwasher on a water heat/heated dry setting. Leave in the dishwasher (so they will remain hot) until ready to fill with tomatoes. Alternately, you can wash with soapy water and fill with boiling water to heat the jars. Then pour out the boiling water just prior to filling with tomatoes.
2) Wash tomatoes, rubbing gently to remove any soil, dried leaves, etc.
3) Cut away any spots on the tomato that have spoiled. Then cut an X into the skin of the bottom of the tomatoes (not too deep) and plunge them into the pot of boiling water for 30 -60 seconds.
4) Carefully remove the blanched tomatoes when you see the skins begin to pull away. You will probably only want to do 5 or 6 at a time (depending on the size of your pot of water), so that you will be able to remove them quickly when they are ready. You do not want to cook the tomatoes in this step, only remove the skins.
5) Put the tomatoes in a bowl or sink of ice water to stop the cooking process and cool the tomatoes. Remove when cool and place in a bowl or on a tray until ready to peel.
6) Peel the skins away by hand. Carefully (they are slippery!) remove the core, then quarter or slice the tomatoes. The chopping process will cause the tomatoes to release more of their natural juices in the canning process, so for a more firm product, keep them whole or in large chunks.
7) When you have an 8-9 quart bowl filled with peeled and chopped tomatoes, you are ready to start filling your jars. If pressure canning, boil 3 quarts of water and place in the pressure canner. Add 2 Tbs of white vinegar to the water to keep from having water lines on your jars. If water-bath canning, fill the canner about 1/2 full of water and boil. Have extra boiling water on hand for covering the jars once they are inserted into the canner.
8) Pour 1/2 teaspoon of citric acid (or 2 Tbs of bottled lemon juice) in the bottom of the heated quart jars. Put 1/2 to 1 teaspoon of canning and pickling salt in each jar (can use other types of salt, but this one dissolves faster).
9) Scoop the tomatoes (by hand or with a slotted spoon) into the jars using a wide-mouth canning funnel as pictured above. Pack them firmly into the jar, and try to force the air bubbles out with a clean wooden or plastic cooking spoon, spatula, or cocktail muddler. Leave 1/2 inch of head space in the jar.
10) Wipe the rims of the filled jars with a clean, damp cloth (you can use a little white vinegar on the cloth to help limit bacteria if you like). Top the jars with the sterilized and heated lids. Place the bands on the jars and screw on "fingertip tight" which means to the point of resistance, but not tight.
11) Place the jars in the canner on top of the rack, being careful that they do not touch each other or the sidewalls of the canner. Follow manufacturer's instructions for using your pressure canner. Most state that after pressure is reached, tomatoes need to process at 5lbs of pressure for 40 minutes to ensure food safety (See guidelines for high altitude canning times if above 1000ft). Once the tomatoes have processed for the full time, turn off heat and let the canner gradually cool. Do not try to remove the lid or release pressure prematurely. This can cause the jars to not seal properly. Follow manufacturer's instructions for the removal of processed jars.
12) For water bath canning, cover the jars with boiling water (about 1/2 inch over the tops of the lids) and let water come to a boil before starting process time. Cover with a vented lid. Once the water is boiling set timer for 85 minutes. If using a pressure canner as a water-bath canner, remove the weight and rubber vent stopper from the lid so the steam can escape. Lock the lid in place while processing to keep water from splashing out. When the processing time is complete, turn off the heat and carefully remove the jars from the canner with canning tongs. Place them on a clean cloth or paper and let cool. Do not touch the lids until the jars have completely cooled. You may hear a pop sound when the lids seal as the jars gradually cool.
13) When the jars have completely cooled, check that they have properly sealed by pressing in the center of the lid. It should be firm with no movement. If it pops up and down then it has not sealed properly. If the jars are sealed, remove the bands and wipe around the lids with a clean damp cloth. You can use a little white vinegar on the cloth to help lift any residue. At this point the bands are not necessary, but if you want to leave them on, clean the inside of the bands and make sure they are dry before placing them on the jars. Store your jars of tomatoes on a shelf that is cool and dark. Refrigeration is not necessary until opened.