If you want to know how to can diced tomatoes with a pressure cooker, the process is simpler than you might think. Diced tomatoes processed in a pressure cooker retain firmer texture than water bath versions and allow you to skip the added lemon juice if you prefer. That makes them a great choice for soups, stews, and casseroles where you want the tomatoes to hold there shape.
Pressure canning uses higher temperatures than boiling water. This kills bacteria and spores that water bath canning cannot reach. For low-acid foods, pressure canning is the only safe option. But tomatoes sit in a middle ground. They are acidic, yet not always acidic enough on their own.
With a pressure cooker, you get more flexibility. You also get a faster total time once the canner is up to pressure. This guide walks you through every step, from choosing tomatoes to checking the seals.
Why Use A Pressure Cooker For Diced Tomatoes
Tomatoes have a pH that usually falls between 4.0 and 4.6. The safe cutoff for water bath canning is 4.6. Some tomatoes, especially overripe ones or those grown in cooler climates, can creep above that line. A pressure cooker eliminates that worry because it reaches 240°F (116°C).
Another benefit is texture. Water bath canning cooks tomatoes longer at a lower heat, which can turn them mushy. Pressure canning gets the job done faster, so the diced pieces stay more firm. You also do not need to add lemon juice or citric acid if you pressure can, though you still can if you like the taste.
Equipment You Will Need
- A pressure canner, not just a pressure cooker. Most modern electric pressure cookers are not approved for canning. Check your manual.
- Glass canning jars (pint or quart) with new lids and bands.
- A jar lifter, funnel, and bubble remover.
- A large pot for blanching tomatoes.
- A bowl of ice water.
- Sharp knives and a cutting board.
If you only have a stovetop pressure cooker, make sure it holds at least 4 quart jars and has a pressure gauge or weighted regulator. Never use a slow cooker or a multi-cooker that lacks a canning setting.
How To Can Diced Tomatoes With A Pressure Cooker
Follow these steps in order. Do not skip the prep work. Clean jars and proper headspace are just as important as the pressure time.
Step 1: Pick And Prep Your Tomatoes
Use firm, ripe tomatoes. Roma or paste varieties work best because they have less water and fewer seeds. Wash them well under running water. Remove any stems or bruised spots.
To peel them easily, cut a small X on the bottom of each tomato. Drop them into boiling water for 30 to 60 seconds. Then move them straight into ice water. The skins will slip right off.
Core the tomatoes and cut them into quarters. Remove excess seeds if you want a thicker product. Now dice the quarters into pieces about half an inch thick. Set them aside in a large bowl.
Step 2: Prepare The Jars And Lids
Wash your jars in hot soapy water. Rinse them well. You do not need to sterilize jars if you will process them for 10 minutes or more, but many people still do. Keep them hot until you fill them. Simmer the lids in a small pan of water, but do not boil them hard.
Step 3: Fill The Jars With Diced Tomatoes
Pack the diced tomatoes into hot jars using a funnel. Leave 1 inch of headspace at the top. Add 1/2 teaspoon of salt per pint or 1 teaspoon per quart if you like. Salt is for flavor only, not safety.
You can add a tablespoon of bottled lemon juice per pint if you want extra insurance. But with pressure canning, it is not required. Use a bubble remover or a plastic knife to remove air pockets. Wipe the jar rims with a clean, damp cloth.
Place the lids on and screw the bands until they are fingertip tight. Do not force them.
Step 4: Load The Pressure Canner
Put 2 to 3 inches of hot water in the bottom of your pressure canner. Place the rack inside. Use a jar lifter to set the jars on the rack. Leave space between them so steam can move around.
Lock the lid on the canner. Turn the heat to high. Let steam escape for a full 10 minutes before you put the weight on or close the petcock. This step removes air from the canner and is critical for safety.
Step 5: Bring To Pressure And Process
After the 10-minute venting, add the weighted gauge or close the petcock. Watch the gauge. For pints of diced tomatoes, process at 11 pounds of pressure (psi) for 15 minutes if you are below 2,000 feet elevation. For quarts, process for 20 minutes. If you live higher, adjust the pressure according to a canning chart.
Start your timer only when the correct pressure is reached. Keep the pressure steady. Small movements are fine, but do not let it drop below the target.
Step 6: Cool Down And Check Seals
When the time is up, turn off the heat. Let the canner cool on its own. Do not rush this. Do not run cold water over it. Wait until the pressure gauge reads zero and the lid unlocks easily.
Open the canner and let the jars sit inside for 5 more minutes. Then remove them with a jar lifter. Set them on a towel or rack, away from drafts. Let them cool for 12 to 24 hours.
Press the center of each lid. If it does not pop up and down, the jar is sealed. Remove the bands. Wipe the jars clean. Label them with the date.
Common Mistakes To Avoid
- Using a pressure cooker that is not rated for canning. This is unsafe.
- Forgetting to vent steam for 10 minutes. Skipping this traps air and lowers the temperature.
- Packing tomatoes too tightly. Leave that 1 inch of headspace.
- Changing the pressure or time. Follow tested guidelines from a trusted source.
- Cooling the canner too fast. Cracked jars or broken seals can result.
Storage And Shelf Life
Store your sealed jars in a cool, dark place. A pantry or basement works well. Keep them between 50°F and 70°F. Properly canned diced tomatoes last 12 to 18 months. After that, they are still safe but the quality drops.
If a jar loses its seal, smells off, or shows any mold, throw it out. Do not taste it to check. When in doubt, toss it out.
Now you know how to can diced tomatoes with a pressure cooker. The process takes some time, but the result is worth it. You get firm, flavorful tomatoes that are ready for any recipe. Start with a small batch of pints to practice. Then scale up when you feel comfortable.