Canning tomatoes at home is a time-honored way to preserve summer’s bounty, ensuring you have delicious, ripe tomatoes on hand all year round. While traditional water bath or pressure canning methods require special equipment, many home cooks wonder if they can use their Instant Pot for canning. This guide explains how to use your Instant Pot for preparing tomatoes for canning and walks you through the safe steps for canning tomatoes at home. Note: The Instant Pot is not approved as a substitute for a pressure canner for low-acid foods, but it can be used for water bath canning of high-acid foods like tomatoes (with added acid). You’ll also learn what supplies you need, common mistakes, tips, troubleshooting, and answers to frequently asked questions.
What You’ll Need
- Fresh, ripe tomatoes (Roma or other canning varieties are best)
- Lemon juice or citric acid (to ensure safe acidity)
- Non-iodized salt (optional, for flavor)
- Instant Pot (6-quart or larger)
- Canning jars (pint or quart size), lids, and bands
- Jar lifter or tongs
- Large bowl for ice water
- Slotted spoon
- Large pot for blanching (optional, but makes peeling easier)
- Funnel and bubble remover (optional but helpful)
- Clean towels
Step-by-Step
- Prepare Your Workspace: Wash your hands and clear a large, clean work area. Gather all your supplies and sterilize your canning jars and lids by washing them in hot, soapy water and rinsing well. You can sterilize jars by placing them in the Instant Pot on the steam rack with 1 cup of water and using the ‘Steam’ function for 10 minutes, then keeping them hot until ready to use.
- Wash and Blanch Tomatoes: Rinse tomatoes thoroughly. To easily peel, bring a large pot of water to a boil. Score a small “X” on the bottom of each tomato, then drop them into boiling water for 30-60 seconds until skins start to split. Immediately transfer to a bowl of ice water. Peel off skins and remove cores.
- Prepare Tomatoes for Canning: Decide if you want to can whole, halved, or crushed tomatoes. For whole or halved, cut tomatoes as desired. For crushed, place pieces in a pot, mash slightly, and heat until boiling for 5 minutes.
- Add Acid: To ensure safe acidity, add 2 tablespoons of bottled lemon juice (or 1/2 teaspoon citric acid) per quart jar, or 1 tablespoon lemon juice (or 1/4 teaspoon citric acid) per pint jar. This step is essential, as tomatoes are borderline in acidity and must be acidified for safe canning.
- Fill Jars: Pack tomatoes into hot jars, leaving 1/2-inch headspace. If desired, add 1 teaspoon salt per quart for flavor. Use a funnel to keep rims clean. For crushed tomatoes, ladle hot tomatoes and juice into jars.
- Remove Air Bubbles: Slide a bubble remover or a non-metallic spatula around the inside of the jar to release air bubbles. Adjust headspace if needed by adding more tomatoes or juice.
- Wipe Rims and Seal: Wipe jar rims with a clean, damp cloth to remove residue. Place lids on jars and screw bands on until fingertip tight.
- Set Up the Instant Pot: Place the trivet or steam rack in the bottom of the Instant Pot. Add 1-2 cups of water (as per your model’s minimum liquid requirement). Arrange jars on the rack, making sure jars do not touch the sides or each other. Depending on your model, you may only be able to fit 2-4 jars at a time.
- Process the Jars: Secure the Instant Pot lid and set the valve to ‘Venting’ (for water bath-style canning, you want to avoid pressure buildup). Use the ‘Steam’ function. Process pint jars for 40 minutes or quart jars for 45 minutes. Note: The USDA does not currently recommend using an Instant Pot for pressure canning, but for water bath canning of high-acid foods, this method is acceptable. Always check your Instant Pot’s manual for any specific warnings.
- Cool and Check Seals: When processing time is up, carefully lift jars out using a jar lifter and place them on a towel. Let cool undisturbed for 12-24 hours. Once cool, check seals by pressing the center of each lid. If the lid does not flex up and down, the jar is sealed. If a jar did not seal, refrigerate and use within a few days.
- Label and Store: Label jars with the date and contents. Store sealed jars in a cool, dark place. Properly sealed jars can last up to a year; always check for spoilage before use.
Common Mistakes
- Skipping Acid Addition: Not adding lemon juice or citric acid can result in unsafe jars, as tomatoes alone may not be acidic enough to prevent botulism.
- Overfilling Jars: Filling jars past the recommended headspace can cause jars to leak or not seal properly.
- Poor Jar Sealing: Not wiping jar rims or overtightening bands can prevent proper sealing.
- Using Damaged Jars: Cracks or chips in jars can cause breakage during processing.
- Processing at Pressure: Using the Instant Pot’s pressure setting for canning tomatoes is not USDA approved and can be unsafe for home canning.
- Not Following Processing Times: Shortening processing times increases the risk of spoilage and foodborne illness.
Tips
- Use Bottled Lemon Juice: Bottled lemon juice has a consistent acidity, whereas fresh lemons can vary. This ensures safer canning.
- Choose the Right Tomatoes: Paste varieties like Roma yield thicker sauces and fewer seeds.
- Work in Batches: If you have lots of tomatoes, process in small batches for best results and to avoid rushed, unsafe steps.
- Keep Jars Hot: Hot jars help prevent cracking when filled with hot tomatoes.
- Date Your Jars: Always label with the date so you use the oldest first.
- Store in a Cool, Dark Place: Light and heat can degrade quality and shorten shelf life.
- Check Seals Before Storing: Never store unsealed jars at room temperature; refrigerate and use them promptly.
Troubleshooting
- Jars Didn’t Seal: If lids do not pop down and seal after cooling, refrigerate and use within a few days. Do not attempt to reprocess using the Instant Pot, as repeated heating can degrade quality and does not guarantee safety.
- Liquid Loss in Jars: Some liquid loss is normal. Excessive loss may mean jars were overfilled or bands were too tight. As long as the jars are sealed and tomatoes are covered, the contents are safe.
- Cloudy Liquid: This can be caused by using table salt or hard water. As long as there is no foul odor or signs of spoilage, it is safe to eat.
- Tomatoes Float: Floating tomatoes are common and not a safety issue. Next time, pack tomatoes more tightly and remove air bubbles thoroughly.
- Jars Cracked or Broke: This usually happens if jars were cold when filled or had chips/cracks. Always use hot jars and inspect for damage before use.
- Signs of Spoilage: If you notice bubbling, leaking, mold, or off smells, discard the jar contents immediately. Never taste food from a jar with these signs.
Frequently Asked Questions
- Can I use my Instant Pot for pressure canning tomatoes?
- No. The Instant Pot is not approved for pressure canning because it does not reliably reach or maintain the temperatures needed to safely can low-acid foods. Only use it for water bath canning high-acid foods, with added acid.
- Is it safe to can tomatoes without lemon juice or citric acid?
- No. Tomatoes must have added acid to ensure safety. This step prevents the growth of Clostridium botulinum, which causes botulism.
- How long do home-canned tomatoes last?
- Properly processed and sealed jars can last up to one year when stored in a cool, dark place. Always check for spoilage before use.
- Can I reuse canning lids?
- No. Always use new lids for each canning session. Used lids may not seal properly, risking spoilage.
- What if I see bubbles in the jar after canning?
- Some small bubbles are normal if they are not moving. If bubbles are rising or the jar is leaking, discard the contents.
- Can I add herbs, garlic, or onions to my canned tomatoes?
- It’s safest to can plain tomatoes and add herbs or vegetables when you open the jar to use them. Added vegetables can lower acidity and may make the product unsafe for water bath canning.
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