Steaming Tomatoes: How Long For Perfect Results?

How Long Does It Take to Steam Pressure Cook Tomatoes?

Steam pressure cooking tomatoes can take anywhere from 15 to 85 minutes, depending on the method used.

Boiling-Water Bath

The boiling-water bath method involves submerging jars of tomatoes in a large pot of boiling water. The processing time for this method is typically around 85 minutes.

Pressure Canner

When using a pressure canner, the processing time is significantly reduced. For example, the processing time for pints or quarts of tomatoes in a pressure canner is only 25 minutes at 10 psi.

Factors Affecting Processing Time

It's important to note that the processing time may vary depending on factors such as altitude and the specific type of canner being used. For instance, at higher altitudes, the processing time for a boiling-water bath may need to be increased by 5 minutes for every 1,000 feet above sea level.

Additionally, different types of pressure canners, such as dial-gauge and weighted-gauge canners, may have slightly different processing times and procedures. It's always important to follow the specific instructions for your canner and adjust the processing time as needed.

Selecting the tomatoes

Selecting the right tomatoes is a crucial step in the canning process. Here are some tips to help you choose the best tomatoes for pressure cooking or canning:

Choose High-Quality Tomatoes:

Start by selecting fresh, vine-ripened tomatoes that are at their peak ripeness. Avoid over-ripe tomatoes as they have lower acidity levels. The ideal tomatoes for canning are those that are slightly under-ripe or just fully ripe. Look for bright, vibrant colours and avoid any with soft spots, bruises, or damage.

Avoid Damaged Tomatoes:

Do not use damaged tomatoes or those from dead or frost-killed vines. These tomatoes may have extra pathogens, and the standard canning processing time may not be sufficient to kill all disease-causing organisms. This could lead to spoilage and potentially unsafe food.

Consider the Variety:

Plum or Roma tomatoes are often recommended for canning because they have a firmer texture and fewer seeds. However, you can also use other varieties such as San Marzano, Big Mama, or Jersey Giant. Meaty tomato varieties tend to work best for canning.

Amount of Tomatoes:

As a general rule of thumb, you'll need about 1.5 pounds of fresh tomatoes to fill a pint jar and 3 pounds for a quart jar. If you're making a large batch, you can pre-order from a local farm or farmer's market.

Taste and Texture:

Look for tomatoes with a balance of sweetness and acidity. Firmer, less ripe tomatoes tend to hold their shape better during the canning process. Avoid tomatoes that are too soft as they may fall apart.

Wash and Inspect:

Before canning, wash the tomatoes thoroughly and inspect them for any imperfections or cracks. Remove any stems or leaves. You want your tomatoes to be clean and free of dirt or debris.

Remember, choosing the right tomatoes is essential for the best results and to ensure food safety. Always select high-quality, ripe tomatoes, and avoid any that are damaged or past their prime. With these tips in mind, you'll be well on your way to selecting the perfect tomatoes for pressure cooking or canning!

Sanitising the jars

Step 1: Sterilise the Jars and Lids

Wash your empty canning jars in hot, soapy water, and rinse them thoroughly. Place the jars in a boiling-water canner and cover them with hot water. Bring the water to a simmer over medium heat and let the jars simmer for 10 minutes. Keep the jars in the simmering water until you are ready to fill them. When you are ready, remove one jar at a time from the water and place it on a clean kitchen towel to prevent slipping.

Step 2: Prepare the Lids

While the jars are simmering, place the lids in a separate bowl and pour over some hot water from the sterilising pot. Do not boil the lids, and keep in mind that the screw bands do not need to be sterilised.

Step 3: Acidify the Jars

For each quart jar, add two tablespoons of bottled lemon juice or half a teaspoon of citric acid. If using pint jars, use half these amounts. This step is crucial to ensure a safe acidity level.

Step 4: Add Salt (Optional)

If desired, add a teaspoon of pure sea salt or kosher salt to each jar. This is for flavour only and can be omitted.

Step 5: Fill the Jars

Gently pack the tomatoes into the jars, taking care not to squish them. Leave a 1/2-inch headspace at the top of each jar. Remove any air pockets and use the remaining liquid from the tomatoes (or water) to cover the tomatoes if needed.

Step 6: Wipe the Jars

Use a damp towel to wipe the rims of the jars, removing any food residue. This step is important to ensure a proper seal.

Step 7: Place the Lids

Place the lids on top of the jars and screw on the rings until they are finger-tight. Over-tightening the lids can interfere with the canning process.

Now your jars are sanitised and ready for the next steps of the canning process!

Removing the tomato skins

Removing the skins from tomatoes is a crucial step in the canning process. It not only improves the taste and texture of the final product but also ensures safety by reducing the bacterial load. Here are some detailed instructions on how to effectively remove tomato skins:

Method 1: Using a Large Pot of Boiling Water

• Wash the tomatoes thoroughly and remove any leaf or stem remnants.
• Using a paring knife, carefully score the skin of each tomato by making a small 'X' at the top.
• Bring a large pot of water to a boil.
• Carefully lower the tomatoes into the boiling water using a slotted spoon or tongs.
• Let the tomatoes remain in the boiling water for about 30 to 60 seconds, or until you see the skins starting to loosen or wrinkle around the edges of the score marks.
• Using the slotted spoon or tongs, transfer the tomatoes to a large bowl of ice water to stop the cooking process and allow them to cool.
• Once the tomatoes are cool enough to handle, gently pull and slide off the skins and discard them. Alternatively, you can reserve the skins for dehydrating or making tomato powder.

Method 2: Using an Instant Pot or Pressure Cooker

• Place 1 1/2 cups of hot or boiling water into your Instant Pot or pressure cooker.
• Place a steamer basket inside the pot.
• Remove the stems from the tomatoes and place them into the steamer basket.
• Secure the lid on the pot, ensuring that the valve is set to sealing.
• Set the manual/pressure cook button to 0 (zero) minutes. The pot will build up pressure and then immediately turn to the keep warm setting.
• Once the pot beeps, carefully move the valve to venting to release the pressure.
• When the pressure is fully released, carefully remove the lid.
• Use tongs to transfer the tomatoes to an ice bath to cool them down.
• Once the tomatoes are cool to the touch, the skins should slide off easily.

Additional Tips:

• It is recommended to remove the skins from all varieties of tomatoes, including cherry tomatoes, before canning.
• If you are short on time, you can freeze tomatoes with their skins on. When you're ready to can, simply thaw the tomatoes, and the skins will slip off easily.
• Removing the skins is important not only for safety but also for improving the texture and taste of your canned tomatoes. Tomato skins can leave chewy bits in the final product and impart a bitter flavour due to the presence of flavonols.

Filling the jars

Step 1: Prepare the Tomatoes

Before filling the jars, you must first prepare the tomatoes. Wash the tomatoes and remove any stems or leaves. To easily remove the skins, create a small cut or an 'X' on the top of each tomato. This will help the skin peel off smoothly. Place the tomatoes in a pot of boiling water for about 30 seconds to 1 minute, and then immediately transfer them to a bowl of ice water. The skin should now slide off easily. You can also use a paring knife to remove any remaining skin and cut off any bruises or tough parts.

Step 2: Prepare the Jars

It is essential to sanitise your jars before filling them. You can do this by washing them with hot soapy water and rinsing them thoroughly. Alternatively, you can run them through a dishwasher with a sanitise cycle. Prepare enough jars to fit your tomatoes, usually pint or quart-sized jars.

Step 3: Add Acid and Salt (Optional)

Adding acid to your tomatoes is a critical step to ensure their safety during long-term storage. The acidity prevents the growth of harmful bacteria. For each quart jar, add 2 tablespoons of bottled lemon juice or 1/2 teaspoon of citric acid. If using pint jars, add 1 tablespoon of lemon juice or 1/4 teaspoon of citric acid. You can also add 1 teaspoon of salt per quart or 1/2 teaspoon per pint for flavour, but this is optional and can be omitted.

Step 4: Pack the Jars

Now it's time to fill your jars with tomatoes! Gently pack the tomatoes into the jars, ensuring they are tight but not squished. Leave about 1/2 inch of headspace at the top of each jar. If using whole tomatoes, you may need to cut them into halves or quarters to fit comfortably in the jar.

Step 5: Remove Air Bubbles

Use a thin, flat utensil, such as a plastic knife or spoon, to remove any air bubbles from the jars. Gently slide the utensil up and down around the inside edge of the jar to release trapped air.

Step 6: Wipe the Jar Rims

Before placing the lids on the jars, use a damp cloth or paper towel to wipe the rims of the jars. This step is important to ensure there are no food bits or residue that may interfere with the sealing process.

Step 7: Place the Lids and Rings

Place the lids on top of the jars and screw on the rings snugly, but not too tight. Over-tightening the lids can affect the canning process. The contact surfaces between the jar and lid should be clean to ensure a good seal.

Your jars are now filled and ready for the next steps in the canning process! Remember to follow safe canning procedures and adjust processing times according to your altitude.

Adding lemon juice and liquid

Tomatoes are very close to the safety borderline for pH levels. To prevent the growth of Clostridium botulinum bacteria, which causes botulism, it is recommended that you acidify your tomatoes before canning. Lemon juice, citric acid, or vinegar can be used to acidify your tomatoes. However, vinegar may impact the taste of the tomatoes, so lemon juice or citric acid are preferable.

The amount of lemon juice or citric acid you add to your tomatoes depends on the quantity of tomatoes you are canning. For quart-sized jars, add two tablespoons of lemon juice or half a teaspoon of citric acid. For pint-sized jars, use one tablespoon of lemon juice or a quarter of a teaspoon of citric acid.

It is important to use bottled lemon juice rather than fresh lemon juice, as bottled lemon juice has a known acidity level and will ensure consistency across jars.

In addition to acidifying your tomatoes, you should also add salt for flavour. This is optional and can be omitted if desired. Generally, you will add one teaspoon of salt per pint and two teaspoons of salt per quart.

Frequently asked questions