Peel washed tomatoes, pack hot into jars with bottled lemon juice, seal, and process at 11 PSI (dial) or 10 PSI (weighted) for 25 minutes.
Preserving the summer harvest lets you enjoy rich flavors all winter long. Many home cooks ask, “how do you can tomatoes with a pressure cooker?” because this method is faster and more water-efficient than the traditional water bath method.
Using a pressure canner allows the internal temperature to exceed boiling, which kills potential bacteria effectively. However, tomatoes occupy a unique middle ground in acidity. Even when you use a pressure unit, specific rules regarding acid and timing apply to keep the food safe.
This article details the exact equipment, preparation methods, and processing times required. You will learn safe operating procedures for your pressure canner to prevent jar breakage and spoilage.
Pressure Canner Vs Pressure Cooker: A Critical Safety Note
Before starting, we must distinguish between a standard pressure cooker and a pressure canner. Most multi-cookers or small sauce-pan style pressure cookers are not safe for canning. They heat up and cool down too quickly, which interferes with the thermal process needed to kill bacteria.
Safe equipment — Use a dedicated stovetop pressure canner. These large pots can hold at least four quart jars standing upright. They have heavy lids with clamps or locking mechanisms, a pressure gauge (dial or weighted), and a vent pipe.
Electric models — Avoid electric multi-cookers unless the manufacturer explicitly sells them as “canners” with USDA-tested approval. Most electric units fluctuate in pressure too much to guarantee a safe seal for low-acid adjustments.
For the purpose of this guide, when we discuss the process of how do you can tomatoes with a pressure cooker, we refer to the large, stovetop pressure canner designed for preservation.
Essential Equipment For Canning Tomatoes
You need more than just the canner and the produce. Gathering the right tools beforehand prevents panic when handling hot jars.
Jars And Lids
Mason jars specifically made for canning are mandatory. Reusing mayonnaise or pasta sauce jars is risky because the glass is often too thin to withstand the pressure shifts.
- Inspect glass — Check rims for chips or cracks. Even a hairline fracture can cause a jar to shatter inside the canner.
- Prep lids — Wash new flat lids with warm soapy water. You no longer need to boil them, as modern sealing compound works best at room temperature.
- Check bands — Ensure screw bands are rust-free and fit the jar threads smoothly.
Acid Source
Tomatoes vary wildly in pH. Some modern varieties are less acidic than heirloom types. To guarantee safety against botulism, you must acidify every jar, even when pressure canning.
- Bottled lemon juice — This is the standard choice. It has a consistent acidity level that fresh lemons lack.
- Citric acid — A white powder available in canning aisles. It does not alter the flavor as much as lemon juice.
- Vinegar — You can use 5% acidity vinegar, but it may change the flavor profile of your tomatoes significantly.
Jar Lifting Tools
Handling jars at 240°F requires specialized tongs. A “jar lifter” grabs the neck of the jar securely. Do not use standard kitchen tongs, as they slip easily on wet glass. A canning funnel also helps keep rims clean during the packing stage.
Preparing Tomatoes For The Pressure Canner
Great texture starts with proper prep. Leaving skins on creates a tough, papery product, so peeling is the standard first step.
Washing And Blanching
Bacteria live on the skin of the fruit. Wash every tomato under cool running water and remove any bruised areas or stems.
- Boil water — Bring a large stockpot of water to a rolling boil.
- Score fruit — Cut a shallow “X” on the bottom of each tomato. This helps the skin split.
- Dip tomatoes — Lower them into boiling water for 30 to 60 seconds until skins begin to curl.
- Shock them — Transfer immediately to a bowl of ice water. The thermal shock stops cooking and makes skins slip off easily.
Acidification Rules
You must add the acid directly to the jar before filling it with tomatoes. Do not mix it into the main pot of tomatoes, as distribution might be uneven.
- Pints — Add 1 tablespoon of bottled lemon juice or ¼ teaspoon of citric acid.
- Quarts — Add 2 tablespoons of bottled lemon juice or ½ teaspoon of citric acid.
- Taste balance — If the lemon juice makes the tomatoes too tart, you can add a small pinch of sugar to offset the sourness.
How Do You Can Tomatoes With A Pressure Cooker?
This section covers the core process. Precision here ensures a vacuum seal that lasts for years. We will focus on the “Hot Pack” method, as it removes air from the fruit and prevents floating, but “Raw Pack” is also an option.
Step 1: Heating The Tomatoes
Boil the fruit — Place peeled, cored, and quartered tomatoes in a large pot. boil gently for 5 minutes. This releases air trapped in the tomato tissues and helps prevent spoilage.
While the tomatoes simmer, keep your jars hot. You can run them through a dishwasher cycle or leave them in hot water. Putting hot food into cold glass causes breakage.
Step 2: Filling The Jars
Add acid — Place the required lemon juice or citric acid at the bottom of the hot jar.
Pack tomatoes — Ladle hot tomatoes into the jar. Leave 1 inch of headspace at the top. This gap is vital. If filled too high, food boils out and ruins the seal. If too low, the jar may not seal properly.
Remove bubbles — Slide a plastic spatula or chopstick down the sides of the jar to release trapped air pockets. Adjust the headspace if the level drops.
Clean rims — Wipe the rim of the jar with a clean, damp paper towel. Any tomato seeds or juice on the rim will prevent the lid from sticking.
Apply lids — Place the flat lid on top. Screw the band on until “fingertip tight.” Do not wrench it down. Air needs to escape during processing.
Step 3: Operating The Pressure Canner
Now we address the specific mechanics of the query: how do you can tomatoes with a pressure cooker correctly?
- Add water — Pour 2 to 3 inches of hot water into the bottom of your pressure canner. Check your manual, as some brands require specific amounts.
- Load jars — Place jars on the rack inside the canner. Jars should not touch the bottom metal directly.
- Lock lid — Secure the canner lid. Leave the vent pipe open (do not put the weight on yet).
- Turn up heat — Use high heat to bring water to a boil.
- Vent steam — Watch for a steady stream of steam escaping the vent pipe. Let it vent continuously for 10 minutes. This purges air pockets that create cold spots.
- Pressurize — After 10 minutes, place the weighted gauge on the vent or close the petcock. Watch the dial gauge rise.
Step 4: Timing The Process
Start your timer only when the pressure gauge reaches the target PSI. You must maintain this pressure for the entire duration. If pressure drops below the target, you must bring it back up and restart the timer from zero.
Standard timing — Process both pint and quart jars for 25 minutes. This time applies if you are using the hot pack method without added vegetables.
Pressure And Altitude Adjustments
Water boils at lower temperatures at higher elevations. To compensate, you must increase the pressure. Using the standard 10 PSI at high altitudes is unsafe because the internal temperature won’t kill the necessary bacteria.
Dial Gauge Canners
Dial gauges offer precision but need annual testing for accuracy. Read the dial carefully.
- 0 – 2,000 ft — 11 PSI
- 2,001 – 4,000 ft — 12 PSI
- 4,001 – 6,000 ft — 13 PSI
- 6,001 – 8,000 ft — 14 PSI
Weighted Gauge Canners
Weighted gauges rock or spin to release excess pressure. They are durable and do not lose calibration.
- 0 – 1,000 ft — 10 PSI
- Above 1,000 ft — 15 PSI
Note that weighted gauges usually only come in 5, 10, and 15 PSI increments. If you live at 1,200 feet, you must jump to 15 PSI.
Cooling And Storage Procedures
The process does not end when the timer beeps. How you handle the cool-down phase affects the quality of the seal.
Natural Release
Turn off heat — Slide the canner off the hot burner gently. Do not open the lid. Do not run water over the canner.
Wait for zero — Let the pressure drop naturally to zero PSI. This takes 30 to 45 minutes for a full load. Opening the vent too early causes “siphoning,” where liquid is sucked out of the jars.
Remove jars — Once pressure is zero, wait 10 more minutes, then unlock the lid. Lift jars straight up (do not tilt them) and place them on a towel or wooden board. Do not place hot jars directly on a cold stone counter.
Checking Seals
Leave the jars undisturbed for 12 to 24 hours. You will hear “pings” as lids suck down. After cooling, press the center of each lid. It should be concave and firm. If a lid pops up and down, the seal failed. Put that jar in the fridge and eat it within a few days.
Common Canning Mistakes To Avoid
Even experienced canners slip up. Watch out for these errors that compromise safety.
Quick note: The most frequent error is skipping the venting step. If you trap air inside the canner, the temperature inside might be 212°F instead of the required 240°F, even if the gauge reads 11 PSI.
- Overfilling — Leaving less than 1 inch of headspace leads to food trapped under the rim.
- Cooling too fast — Force-cooling the canner warps lids and breaks jars.
- Old ingredients — Use firm, ripe tomatoes. Overripe or decaying fruit has higher pH levels that are harder to preserve safely.
- Omitting acid — Never assume your tomatoes are acidic enough on their own. Always add lemon juice.
Why Choose Pressure Canning Over Water Bath?
Many beginners start with a water bath canner, which simply boils jars. So, why learn how do you can tomatoes with a pressure cooker instead? The primary benefit is efficiency and versatility.
Water bath canning tomatoes often requires 45 to 85 minutes of boiling time depending on your altitude and pack style. A pressure canner finishes the job in 25 minutes. This saves gas or electricity and keeps your kitchen cooler in the summer.
Additionally, if you want to add low-acid ingredients like peppers, onions, or mushrooms to your tomato sauce, you must use a pressure canner. A water bath cannot safely process these mixtures.
Key Takeaways: How Do You Can Tomatoes With A Pressure Cooker?
➤ Always use a dedicated stovetop pressure canner, not a multi-cooker.
➤ Add bottled lemon juice to every jar to ensure safe acidity levels.
➤ Vent the canner for 10 minutes before pressurizing to remove air.
➤ Process pints and quarts for 25 minutes at the correct PSI for your altitude.
➤ Let pressure drop naturally to zero to prevent liquid loss from jars.
Frequently Asked Questions
Do I have to peel tomatoes before pressure canning?
Yes, peeling is highly recommended. Tomato skins carry a heavy load of bacteria from the soil. They also become tough and stringy during processing, which ruins the texture of sauces or salsas. Blanching them makes removal easy.
Can I pressure can tomatoes without lemon juice?
No, you should not skip the acid. While pressure canning reaches higher temperatures, tomatoes are on the borderline of pH safety. Adding lemon juice provides a necessary buffer against botulism spores, regardless of the canning method used.
What happens if the pressure drops during canning?
If the dial drops below your target PSI (11 PSI or 10 PSI), you must bring the heat back up until proper pressure is reached. Then, you must restart your 25-minute timer from the beginning to ensure sterilization.
Can I mix different tomato varieties in one jar?
Yes, mixing varieties like Roma, Beefsteak, or Paste tomatoes is fine. Just ensure all are firm and disease-free. The processing time remains the same regardless of color or variety, provided you acidify the jars correctly.
Is it safe to use an Instant Pot for canning tomatoes?
Generally, no. Most Instant Pot models are not approved for pressure canning because they cannot sustain the precise pressure required for long durations. Only use models specifically designed and tested for canning, or stick to stovetop units.
Wrapping It Up – How Do You Can Tomatoes With A Pressure Cooker?
Mastering the pressure canner opens up a new level of kitchen efficiency. Once you understand the mechanics of venting, pressurizing, and cooling, the process becomes rhythmic and satisfying.
Remember that safety relies on adherence to the rules. Always acidify your jars, check your altitude requirements, and inspect your seals after cooling. With these steps, your pantry will be stocked with high-quality, shelf-stable tomatoes ready for soups, stews, and sauces whenever you need them.