Contents
Types of Food Preservation
Canning and Preserving Tools
Canning and Preserving Ingredients
How to Prepare Jars for Processing
How to Heat-Process Jars
How to Can Food
How to Make Sugar Preserves
How to Pickle
Canning Recipes
Sugar Preserve Recipes
Pickle Recipes
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How to Heat-Process Jars
Heat processing is central to canning, pickling, and preserving. If you intend to can foods or store sugar preserves or most types of pickles at room temperature, you’ll need to heat-process them in jars. Heat processing destroys harmful microbes that are naturally present in food and removes air from the jars, creating the vacuum seal that allows you to store the jars at room temperature until you open them.
There are two main processing methods available to the home cook—choosing the right one depends on the acid content of both the solid food and its surrounding liquid.
Boiling-Water Method
The boiling-water method is a good way to heat-process:
- Foods that are naturally high in acid, such as fruits, juices, and tomatoes
- Low-acid foods that are submerged in an acidic brine, such as acidified and fermented pickles
- Sugar preserves
In the boiling-water method, foods are sealed in glass jars, submerged in a boiling-water canner, and processed at a steady temperature of 212°F for 10–20 minutes or longer,
depending on the recipe. Jars are then removed from the canner and cooled rapidly to ensure that a strong seal forms under the lid. Follow these steps to use the boiling-water method:
- Fill your boiling-water canner half full with water (submerging your jars into the canner will cause the water level to rise, so don’t overfill it).
- Heat the water to 140° for raw-packed food or to 180° for hot-packed food.
- Place packed, filled, and sealed jars in the canner rack insert and lower the rack slowly into the water, making sure that the jars are covered by 2" of water. Add more hot water if needed.
- Bring the water to a boil, put the lid on the canner, start your timer, and process the jars for the time indicated in your recipe. (If you live more than 1,000 feet above sea level, see later in this section for information on altitude adjustments.)
- Using a jar lifter, remove the jars carefully from the canner and place them on a clean, folded towel on a flat surface to cool. Leave at least 2" between jars.
Steam-Pressure Method
Low-acid foods, such as meats and most vegetables, need higher temperatures and longer processing times to kill the bacteria and toxins present in them. Steam-pressure canners can achieve a temperature of 240°F and are used to heat-process such items for canning. Follow these steps:
- Put the canner on your stovetop, insert the canner rack in the canner, and pour 2–3" of water in the bottom.
- Place the packed, filled, and sealed jars in the canner rack and fasten the canner lid securely.
- Leave the vent pipe (called a petcock on some units) open, and turn your burner to medium-high or high until steam begins to flow from it. Allow the steam to release for 10 minutes.
- Using an oven mitt, close the vent or petcock. When the petcock starts to jiggle or the dial gauge shows the desired pressure, start your timer for the time indicated in your recipe. (If you live more than 1,000 feet above sea level, see later in this section for information on altitude adjustments.)
- Maintain a steady temperature by monitoring the dial gauge or making sure that the petcock either jiggles 2–3 times a minute or rocks slowly and steadily (different brands operate differently).
- When the time is up, turn off the heat and remove the canner carefully from the burner. Allow the canner to depressurize on its own—don’t remove the petcock. Cooldown periods for different brands range from 10–45 minutes. Follow the manufacturer’s instructions.
- Remove jars with a jar lifter and place them on clean, folded towels on a flat surface. Leave at least 2" between adjacent jars.
Altitude Adjustments
Since water and steam behave differently as altitude
increases, required processing times are longer if you live at high altitude. Follow the guidelines below.
Boiling-Water Method
If you’re using the boiling-water method at high altitudes, allow the following additional processing times:
Altitude (feet) |
Extra Processing Time Needed |
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1,000–3,000 |
5 minutes |
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3,001–6,000 |
10 minutes |
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6,001–8,000 |
15 minutes |
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8,001–10,000 |
20 minutes |
Steam-Pressure Method
If you’re steam-pressure canning at high altitudes, purchase a canner fitted with a dial gauge and adjust the pounds pressure according to the following guidelines:
Altitude (feet) |
Dial Reading (pounds of pressure) |
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0–2,000 |
11 |
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2,001–4,000 |
12 |
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4,001–6,000 |
13 |
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6,001–8,000 |
14 |
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8,001–10,000 |
15 |
How to Cool Jars
Once you’ve removed your jars to your towel-lined surface and placed them at least 2" apart, let them cool at room temperature for 12–24 hours. Moving or shaking the jars prematurely can cause seal failure, as can retightening bands that may have loosened slightly during processing. Resist the temptation to handle your jars, and instead allow them to cool undisturbed.
How to Check Seals and Store Jars
As your jars cool, you may hear a pinging sound of the lids sealing. This may occur within minutes of removing your jars from your canner or may take as long as several hours. It’s not a problem, though, if you don’t hear an audible ping.
The definitive method for checking seals is to wait until all of your jars have cooled thoroughly and press on the lids with your thumbs. If they feel taut and don’t bounce back when you release the pressure, they have sealed properly. If any jars have failed to seal, store them in your refrigerator or reprocess them by removing the contents and starting the entire process again from jar sterilization.
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