Canning Tomatoes in Your Instant Pot: A Simple and Safe Guide

Canning tomatoes is a fantastic way to preserve the bounty of your garden or a great deal from the farmer’s market, allowing you to enjoy fresh, flavorful tomatoes all year round. While traditional water bath canning can seem daunting, using your Instant Pot as a pressure canner makes the process significantly easier and quicker. This comprehensive guide will walk you through the steps of safely canning tomatoes in your Instant Pot, ensuring you create shelf-stable, delicious preserves.

Table of Contents

Understanding Pressure Canning and Safety

Before we dive into the specifics, it’s crucial to understand the importance of pressure canning, particularly for low-acid foods like tomatoes. Tomatoes are considered a borderline low-acid food, especially modern varieties. This means they require a pressure canning method to reach a high enough temperature to kill harmful bacteria, specifically Clostridium botulinum, which causes botulism. Water bath canning is only safe for high-acid foods like jams, jellies, and some properly acidified fruits.

Pressure canning achieves higher temperatures than boiling water, typically around 240°F (116°C), which is necessary to eliminate the risk of botulism. Using an Instant Pot for pressure canning requires careful attention to safety guidelines and ensuring your model is approved for this purpose. Always consult your Instant Pot’s manual for specific instructions and pressure canning guidelines. Not all Instant Pots are designed for pressure canning, so this step is essential.

Is Your Instant Pot Suitable for Pressure Canning Tomatoes?

The first step is to confirm that your specific Instant Pot model is suitable for pressure canning. Refer to your Instant Pot’s user manual for confirmation. Many newer, larger models are specifically designed for pressure canning and will have clear instructions and safety features for this purpose. If your manual doesn’t explicitly mention pressure canning or recommends against it, it is best to stick to traditional water bath canning or other approved canning methods.

Check for specific features, such as a high-pressure setting and the ability to maintain consistent pressure throughout the canning process. Look for information regarding the pot’s capacity for canning jars. Some smaller Instant Pots might only be suitable for very small batches, while larger models can accommodate several jars at once.

Acidification is Key for Safety

Because modern tomatoes are often lower in acid than heirloom varieties, it’s vital to add acid to your tomatoes before canning, regardless of the canning method you use. This ensures that the pH level is low enough to prevent the growth of botulism. Adding bottled lemon juice, citric acid, or vinegar will lower the pH and make your canned tomatoes safe to consume.

The USDA recommends adding 1 tablespoon of bottled lemon juice or 1/4 teaspoon of citric acid per pint jar of tomatoes. For quart jars, double these amounts. You can also use 4 tablespoons of 5% acidity vinegar per quart. Do not reduce the amount of acid; this is a crucial safety measure.

Gathering Your Supplies

Before you begin, gather all the necessary supplies. Having everything ready will make the canning process smoother and more efficient. Here’s a list of what you’ll need:

Fresh Tomatoes: Choose ripe, firm tomatoes that are free from bruises or blemishes.
Canning Jars: Use proper canning jars (Mason or Ball jars) with two-piece lids (lids and bands). Ensure the jars are free of chips or cracks.
New Lids: Always use new lids for each canning session to ensure a proper seal.
Canning Bands: These are reusable and hold the lid in place during processing.
Bottled Lemon Juice or Citric Acid: For acidification. Do not use fresh lemon juice, as the acidity can vary.
Salt (Optional): For flavor. Use canning or pickling salt, which doesn’t contain additives that can cloud the brine.
Canning Utensils: Jar lifter, wide-mouth funnel, bubble popper/headspace tool.
Clean Kitchen Towels: For wiping jars and surfaces.
Instant Pot with Pressure Canning Function: Make sure it is clean and in good working order.
Instant Pot Trivet: To elevate the jars above the water.

Preparing Your Jars and Lids

Proper preparation of your jars and lids is essential for achieving a good seal.

Washing the Jars: Wash your canning jars in hot, soapy water and rinse them thoroughly. You can also run them through the dishwasher on a hot cycle.
Sterilizing the Jars: While not strictly necessary for pressure canning if the processing time is long enough (10 minutes or more), sterilizing the jars ensures the freshest possible product. Place the clean jars in a large pot of boiling water for 10 minutes. Remove them with a jar lifter and keep them warm until ready to fill. Keep the jars hot until they are filled with the hot tomato mixture.
Preparing the Lids: Follow the manufacturer’s instructions for preparing the lids. Generally, this involves simmering the lids in hot (not boiling) water to soften the sealing compound. Do not boil the lids, as this can damage the sealing compound.

Preparing the Tomatoes for Canning

The next step is to prepare the tomatoes for canning. There are several ways to do this, depending on your preference and the type of tomato product you want to make (whole, crushed, or sauce).

Choosing Your Tomato Preparation Method

Whole Peeled Tomatoes: This method involves removing the skins and canning the tomatoes whole. It’s ideal for preserving the tomatoes’ shape and texture.
Crushed Tomatoes: This method involves crushing the tomatoes before canning. It’s a good option for a chunkier tomato product.
Tomato Sauce: This method involves cooking and pureeing the tomatoes into a smooth sauce before canning. This requires a longer cooking time to achieve the desired consistency.

Peeling the Tomatoes

To peel the tomatoes, you can use the blanching method:

Bring a large pot of water to a rolling boil.
Cut a shallow “X” on the bottom of each tomato.
Carefully lower the tomatoes into the boiling water for 30-60 seconds, or until the skins start to crack.
Remove the tomatoes with a slotted spoon and immediately transfer them to a bowl of ice water.
The skins should now slip off easily with your fingers.

Preparing Whole or Crushed Tomatoes

Whole Tomatoes: After peeling, you can leave the tomatoes whole or cut them in half or quarters, depending on their size.
Crushed Tomatoes: After peeling, crush the tomatoes with your hands or a potato masher.

Making Tomato Sauce

After peeling, chop the tomatoes coarsely.
Cook the chopped tomatoes in a large pot over medium heat, stirring frequently, until they break down and release their juices.
Simmer the tomatoes, uncovered, until the sauce reaches your desired consistency. This may take several hours.
Use an immersion blender or food mill to puree the sauce until smooth.

Canning Tomatoes in the Instant Pot: Step-by-Step

Now that you’ve prepared your jars, lids, and tomatoes, you’re ready to start canning in your Instant Pot.

Filling the Jars

Place a warm jar on a protected surface (like a cutting board with a towel).
Use a wide-mouth funnel to carefully fill the jar with the prepared tomatoes, leaving the recommended headspace (usually ½ inch for tomatoes). Headspace is the space between the top of the food and the top of the jar.
Add the appropriate amount of bottled lemon juice or citric acid to each jar (1 tablespoon lemon juice or ¼ teaspoon citric acid per pint, double for quarts).
Add salt, if desired (usually ½ teaspoon per pint, 1 teaspoon per quart).
Use a bubble popper or plastic utensil to remove any air bubbles from the jar. Gently tap the jar on the counter to help release trapped air.
Wipe the rim of the jar with a clean, damp cloth to remove any food residue. This is essential for a proper seal.

Sealing the Jars

Place a prepared lid on the jar, centering it on the rim.
Screw on a canning band until it is fingertip tight. This means the band should be snug but not forced. Overtightening can prevent the jar from sealing properly.

Pressure Canning in the Instant Pot

Place the trivet in the bottom of your Instant Pot.
Add the recommended amount of water to the Instant Pot. Refer to your Instant Pot’s manual for the specific amount of water needed for pressure canning. It’s usually around 2-3 cups.
Carefully lower the filled and sealed jars into the Instant Pot, making sure they don’t touch each other or the sides of the pot. You may need to do multiple batches depending on the size of your Instant Pot.
Close the lid of the Instant Pot and ensure the pressure release valve is set to the “sealing” position.
Select the “Pressure Cook” or “Manual” setting on your Instant Pot.
Set the cooking time according to the chart below, based on your altitude and jar size:

Adjust the pressure setting according to your Instant Pot’s manual and the USDA guidelines. Generally, the recommended pressure for canning tomatoes is 11 PSI.
Once the cooking time is complete, allow the pressure to release naturally. Do not quick release the pressure, as this can cause the jars to break or the seals to fail. Let the pressure release naturally until the float valve drops. This can take 20-30 minutes or longer.
Once the pressure is fully released, carefully open the lid of the Instant Pot.
Use a jar lifter to carefully remove the jars from the Instant Pot. Place them on a towel-lined surface, leaving space between them.
Let the jars cool completely for 12-24 hours. You should hear a “pop” sound as the jars seal.

Checking the Seals and Storing Your Canned Tomatoes

After the jars have cooled completely, check the seals. The lid should be concave (curved inward) and should not flex when pressed. If a jar did not seal, you can either reprocess it with a new lid within 24 hours or store it in the refrigerator and use it within a few days.

Remove the canning bands from the sealed jars. Washing and drying the jars and bands before storing them helps prevent rust. Label the jars with the date and contents and store them in a cool, dark, and dry place. Properly canned tomatoes can be stored for up to 18 months.

Troubleshooting Common Issues

Canning can sometimes present challenges. Here are some common issues and how to address them:

Jars Not Sealing: This can be caused by several factors, including:
- Warped or damaged jar rims.
- Using old or improperly prepared lids.
- Not leaving enough headspace.
- Overtightening the canning bands.
- Insufficient processing time.
If a jar doesn’t seal, reprocess it with a new lid and ensure all steps are followed correctly.
* Siphoning (Liquid Loss from Jars): This can happen during processing if the pressure fluctuates too much or if the jars are overfilled. Ensure consistent pressure and proper headspace.
* Cloudy Liquid: This can be caused by minerals in your water or starch from the tomatoes. It doesn’t necessarily indicate spoilage, but it can affect the appearance of your canned tomatoes. Using distilled water can help prevent cloudiness.
* Mold Growth: This is a clear sign of spoilage. Discard any jars with mold growth without tasting the contents.
* Bulging Lids: This indicates that the contents of the jar are producing gas, which is a sign of spoilage. Discard any jars with bulging lids without tasting the contents.

Enjoying Your Home-Canned Tomatoes

Once you’ve mastered the art of canning tomatoes in your Instant Pot, you’ll have a delicious and versatile ingredient on hand for all sorts of culinary creations. Use your home-canned tomatoes in sauces, soups, stews, chili, salsa, and more. The possibilities are endless! Enjoy the satisfaction of knowing you’ve preserved the taste of summer and created a healthy, homemade pantry staple.

Can I can whole tomatoes in my Instant Pot?

While the Instant Pot is excellent for many cooking tasks, it is not recommended or safe for canning whole tomatoes. Pressure canning requires reaching and maintaining specific high temperatures for extended periods to eliminate botulism spores, and the Instant Pot’s pressure and temperature control during canning have not been scientifically validated for this purpose for whole tomatoes. Therefore, using an Instant Pot for processing whole tomatoes poses a significant health risk.

Instead, focus on recipes specifically designed for Instant Pot canning, such as crushed tomatoes or tomato sauce, following tested and approved guidelines. These recipes often involve adding an acid like lemon juice or citric acid to ensure a safe pH level. Always prioritize safety when canning and rely on reputable sources like the USDA Complete Guide to Home Canning for accurate and reliable information.

What size jars should I use when canning tomatoes in my Instant Pot?

For most Instant Pot canning recipes, pint-sized jars are generally recommended. Their smaller size allows for more even heating and consistent processing within the Instant Pot. Quart jars may not reach the required temperature uniformly, potentially leading to unsafe canned goods.

Before starting, verify your Instant Pot model’s capacity and manufacturer’s instructions regarding suitable jar sizes for canning. Adhering to these guidelines is crucial for ensuring adequate heat penetration and a safe final product. Check if the recipe you’re following has specific jar size recommendations that override the general guidelines.

How much headspace should I leave in the jars when canning tomatoes?

Leaving the correct headspace, typically about ½ inch for tomato products, is vital for proper sealing. Headspace refers to the space between the top of the food and the lid of the jar. This allows for expansion of the contents during processing and creates a vacuum seal as the jars cool.

Insufficient headspace may cause the contents to bubble out during processing, preventing a proper seal. Conversely, excessive headspace can leave too much air in the jar, which might result in oxidation and affect the product’s quality over time. Use a headspace tool or a clean ruler to accurately measure and adjust the headspace before sealing the jars.

Do I need to add lemon juice to the tomatoes when canning them in the Instant Pot?

Yes, adding an acid, such as lemon juice or citric acid, is essential when canning tomatoes, even in an Instant Pot. Tomatoes are naturally borderline in acidity, and adding acid ensures a safe pH level below 4.6, which is required to prevent the growth of botulism spores.

The amount of lemon juice needed depends on the recipe and whether you are using crushed tomatoes, sauce, or pieces. Always follow a tested and approved recipe from a reliable source, such as the USDA Complete Guide to Home Canning, for accurate measurements. Freshly bottled lemon juice is recommended for consistent acidity.

How long should I process the tomato jars in the Instant Pot?

Processing time depends on several factors, including the size of the jars, the type of tomato product (crushed, sauce, etc.), and your altitude. It’s essential to follow a tested and approved recipe for the correct processing time to ensure the elimination of harmful bacteria.

Never shorten the processing time, as this could lead to unsafe canned goods. For instance, crushed tomatoes in pint jars at low altitudes might require 25 minutes of processing at the appropriate pressure. Always adjust the processing time based on your altitude, as higher altitudes require longer processing times. Consult reliable resources like the National Center for Home Food Preservation for altitude adjustments.

How do I know if the jars have sealed properly after canning?

After processing the tomato jars in the Instant Pot, allow them to cool completely undisturbed for 12-24 hours. As the jars cool, the lids should seal, creating a vacuum. A properly sealed jar will have a concave lid that does not flex when pressed.

To check the seal, gently press down on the center of the lid. If the lid flexes or pops up and down, it has not sealed correctly. Sealed jars can be stored in a cool, dark place for up to a year. Unsealed jars should be reprocessed using new lids within 24 hours or refrigerated and used within a few days.

What kind of Instant Pot is best for canning tomatoes?

While many Instant Pot models have a “canning” button or setting, not all are suitable or recommended for pressure canning. The USDA does not endorse pressure canning in electric multi-cookers, including Instant Pots, due to inconsistencies in pressure and temperature regulation. The most crucial aspect is consistent pressure maintenance throughout the entire canning process.

If you choose to use an Instant Pot, it’s best suited for water bath canning of high-acid tomato products like jams, jellies, and certain types of sauces, and only if the recipe specifically states it’s safe to do so. Always consult your Instant Pot’s manual for any manufacturer recommendations or warnings related to canning. If you’re uncertain, consider using a traditional stovetop pressure canner for added safety.