How to Can Tomatoes Using a Blender: A Complete Guide

Canning tomatoes at home is a rewarding way to preserve the taste of summer and ensure a supply of fresh, flavorful tomatoes throughout the year. While traditional methods involve peeling and chopping, using a blender can streamline the process, making it faster and easier. This guide will walk you through every step, from selecting the right tomatoes to safely sealing the jars, ensuring a successful and delicious canned tomato product.

Table of Contents

Understanding the Basics of Canning Tomatoes

Canning is a method of preserving food by heating it in sealed jars to destroy microorganisms that cause spoilage. This process also creates a vacuum seal, preventing air and other contaminants from re-entering the jar. Proper canning techniques are essential for food safety, as improperly canned food can harbor harmful bacteria, such as Clostridium botulinum, which produces botulism toxin.

Why Use a Blender for Canning Tomatoes?

Using a blender offers several advantages over traditional methods. It simplifies the process by:

Reducing prep time: Blending eliminates the need for tedious peeling and chopping. The blender essentially does that labor intensive task for you.
Creating a smoother texture: Blending results in a consistently smooth sauce or puree, perfect for soups, sauces, and other recipes.
Extracting more flavor: Blending helps release more flavor from the tomatoes, resulting in a richer and more vibrant end product.

Choosing the Right Tomatoes for Canning

The variety of tomato you choose greatly affects the flavor and texture of your canned product. It is best to use tomatoes with a high acidity level to ensure safe canning.

Best Tomato Varieties for Canning

Roma tomatoes: These are meaty, have low moisture content, and a good balance of sweetness and acidity, making them ideal for canning.
San Marzano tomatoes: Known for their rich flavor and meaty texture, San Marzano tomatoes are another excellent choice for canning.
Paste tomatoes: Varieties like Amish Paste and Italian Gold are also suitable due to their low water content and dense flesh.

Tomatoes to Avoid

Avoid using low-acid tomatoes, such as some heirloom varieties, unless you add an acidifying agent like lemon juice or citric acid. Always prioritize food safety when canning. Check the pH of the tomatoes using pH strips to ensure it falls within the recommended range (below 4.6 pH).

Essential Equipment for Canning Tomatoes

Having the right equipment is crucial for safe and efficient canning. Here’s a list of essentials:

Water bath canner: A large pot with a rack for holding jars during processing.
Canning jars: Mason jars designed specifically for canning, with lids and bands.
Jar lifter: A tool for safely lifting hot jars out of the canner.
Lid wand: A magnetic tool for lifting lids out of hot water.
Wide-mouth funnel: For easily filling jars without spilling.
Blender: A high-speed blender is preferred for creating a smooth puree.
Kitchen scale: For accurately measuring ingredients.
pH strips or meter: To test the acidity of your tomatoes.

Preparing Your Tomatoes for Blending

Before you start blending, there are a few key steps to prepare your tomatoes.

Washing and Core Removal

Thoroughly wash your tomatoes under cool running water to remove any dirt or debris. Remove the cores from the tomatoes, as they can be bitter. You can use a paring knife or a tomato corer for this step.

Peeling Tomatoes (Optional)

Peeling tomatoes before blending is optional, but it can result in a smoother final product. If you choose to peel them, here’s how:

Bring a large pot of water to a rolling boil.
Score an “X” on the bottom of each tomato.
Drop the tomatoes into the boiling water for 30-60 seconds, or until the skins start to loosen.
Transfer the tomatoes to a bowl of ice water to stop the cooking process.
Peel the skins off the tomatoes.

If you are skipping this step, the blended peel will add additional nutrients and fiber to your canned tomatoes.

Blending the Tomatoes

Now that your tomatoes are prepared, it’s time to start blending.

Blending Process

Place the prepared tomatoes in the blender in batches, being careful not to overfill.
Pulse the blender a few times to break down the tomatoes, then blend on high speed until smooth.
If you prefer a chunkier texture, blend for a shorter amount of time, leaving some small pieces.
Continue blending until all the tomatoes are processed.

Dealing with Seeds

Some people prefer to remove tomato seeds before canning. If you want to remove the seeds, you can strain the blended tomatoes through a fine-mesh sieve or a food mill. However, removing seeds is not necessary for food safety, and many people prefer to leave them in for added flavor and nutrients.

Preparing Your Jars and Lids

Proper jar preparation is essential for creating a good seal.

Sterilizing Jars

While not always necessary, sterilizing jars is recommended, especially for recipes with shorter processing times. Here’s how to sterilize jars:

Place the jars in a water bath canner with enough water to cover them by at least 1 inch.
Bring the water to a boil and boil for 10 minutes.
Keep the jars hot until you are ready to fill them.

Alternatively, you can sterilize the jars in a dishwasher with a sanitizing cycle.

Preparing Lids and Bands

New canning lids are essential for a proper seal. Follow these steps:

Wash the lids in hot, soapy water.
Place the lids in a small saucepan with water, and heat to a simmer (do not boil).
Keep the lids hot until you are ready to use them.
The bands do not need to be sterilized but should be washed in hot, soapy water.

Canning the Blended Tomatoes

Now that your tomatoes are blended and your jars are prepared, it’s time to start canning.

Adding Acidifying Agents

To ensure safe canning, especially with lower-acid tomatoes, you must add an acidifying agent to each jar. The USDA recommends the following:

Lemon juice: Add 2 tablespoons of bottled lemon juice per quart jar, or 1 tablespoon per pint jar.
Citric acid: Add ¼ teaspoon of citric acid per quart jar, or ⅛ teaspoon per pint jar.

Never reduce the amount of acidifying agent, as this can compromise the safety of your canned tomatoes.

Filling the Jars

Remove a hot jar from the canner using a jar lifter.
Place the jar on a towel-lined surface.
Use a wide-mouth funnel to carefully pour the blended tomatoes into the jar, leaving ½ inch of headspace (the space between the top of the tomatoes and the rim of the jar).
Remove any air bubbles by gently tapping the jar on the counter or using a non-metallic spatula to release trapped air.
Wipe the rim of the jar with a clean, damp cloth to remove any food residue.
Center a hot lid on the jar and screw on the band until it is fingertip tight (snug, but not overly tight).

Processing the Jars

Place the filled jars into the water bath canner, ensuring they are covered by at least 1 inch of water.
Bring the water to a rolling boil.
Process the jars according to the recommended time for your altitude and jar size. Refer to a reliable canning guide like the USDA Complete Guide to Home Canning for specific processing times. This resource is a very important key to success.
Once the processing time is complete, turn off the heat and remove the lid of the canner.
Let the jars sit in the hot water for 5 minutes before removing them.

Cooling and Checking the Seals

Carefully remove the jars from the canner using a jar lifter and place them on a towel-lined surface, leaving at least 1 inch of space between the jars.
Let the jars cool completely for 12-24 hours. Do not disturb the jars during this time.
After the jars have cooled, check the seals by pressing down on the center of the lid. If the lid does not flex, it is properly sealed.
Remove the bands and check for proper seals again. If a jar is properly sealed, the lid should remain firmly attached even without the band.
If any jars did not seal properly, you can reprocess them with new lids within 24 hours, or store them in the refrigerator and use them within a few days.

Labeling and Storage

Label each jar with the date and contents. Store the canned tomatoes in a cool, dark, and dry place. Properly canned tomatoes can be stored for up to 1 year.

Troubleshooting Common Canning Issues

Even with careful attention to detail, canning can sometimes present challenges. Here are some common issues and how to address them:

Siphoning

Siphoning occurs when liquid is lost from the jars during processing. This can be caused by:

Overfilling the jars: Ensure you leave the correct amount of headspace.
Fluctuating temperatures: Maintain a consistent boil during processing.
Removing jars too quickly: Let the jars sit in the canner for 5 minutes after processing before removing them.

While a small amount of siphoning is normal, excessive siphoning can lead to food spoilage. Jars with significant siphoning should be reprocessed or refrigerated.

Cloudy Liquid

Cloudy liquid in canned tomatoes can be caused by several factors, including:

Hard water: Use filtered water for canning.
Starch: Overripe tomatoes can release starch during processing.
Sediment: Tiny particles of tomato pulp can settle at the bottom of the jar.

Cloudy liquid does not necessarily indicate spoilage, but it can affect the appearance of the product.

Mold Growth

Mold growth in canned tomatoes is a sign of spoilage and can be caused by:

Improper sealing: Ensure jars are properly sealed before storage.
Insufficient processing: Follow recommended processing times for your altitude and jar size.
Contamination: Use clean jars and utensils.

Never consume canned tomatoes that show signs of mold growth. Discard them immediately.

Adding Flavor to Your Canned Tomatoes

While canned tomatoes are delicious on their own, you can enhance their flavor by adding herbs, spices, and other ingredients during the canning process.

Popular Additions

Herbs: Basil, oregano, thyme, and rosemary are popular choices. Add dried herbs directly to the jars before filling.
Spices: Garlic, onion, and chili flakes can add depth of flavor. Add dried spices to the jars before filling.
Vegetables: Diced onions, peppers, and celery can be added to the blended tomatoes before canning. Be sure to follow approved recipes for adding vegetables to canned tomatoes.
Salt: Add salt to taste. It helps to preserve color and flavor.

Conclusion

Canning tomatoes using a blender is a simple and efficient way to preserve the taste of summer. By following these steps and adhering to proper canning techniques, you can enjoy a supply of delicious, homemade canned tomatoes year-round. Remember to prioritize food safety, use reliable recipes, and enjoy the rewarding experience of home canning. Always consult a trusted canning resource like the USDA Complete Guide to Home Canning for the most up-to-date information and safety guidelines. Happy canning!

Why should I use a blender when canning tomatoes?

Using a blender simplifies the process of canning tomatoes significantly, especially for those who prefer a smoother consistency in their final product. Instead of manually peeling, seeding, and chopping tomatoes, the blender quickly purees them, streamlining the initial preparation stages. This method also helps to ensure a more uniform texture throughout your canned tomatoes, eliminating chunks or large pieces, which can be particularly desirable for sauces, soups, or other recipes where a smooth base is preferred.

Furthermore, blending tomatoes before canning allows for better heat penetration during the processing stage. By breaking down the tomato tissue, the heat can more easily reach the center of the jars, ensuring proper sterilization and reducing the risk of spoilage. This is particularly beneficial for larger batches or when using larger jars, as it ensures a more thorough and consistent canning process, leading to a safer and more shelf-stable final product.

Can I can tomato sauce made in a blender using a water bath canner?

Yes, you can safely can tomato sauce made in a blender using a water bath canner, but it’s crucial to follow specific guidelines for processing times and acidity. Blended tomato sauce can be denser than crushed tomatoes, which can affect heat penetration. Therefore, it’s vital to acidify the sauce properly by adding lemon juice or citric acid to each jar according to recommended recipes to ensure a safe pH level, typically below 4.6.

After adding the acid, carefully fill the jars, leaving the appropriate headspace as specified in your canning recipe (usually ½ inch). Wipe the jar rims clean, place sterilized lids and rings on the jars, and process them in a boiling water bath canner for the time recommended in your recipe. These processing times will vary depending on jar size and your altitude, so always consult a reliable canning resource from a source like the USDA or your local extension office for accurate instructions.

Do I need to remove the tomato skins and seeds before blending for canning?

Whether or not you remove the skins and seeds before blending for canning is largely a matter of personal preference. Leaving them in will slightly affect the final texture and can make the canned tomatoes a bit more fibrous. However, blending with the skins and seeds included can save time and effort during the preparation process, as it eliminates the need for pre-peeling or seeding.

If you choose to leave the skins and seeds, be aware that the blending process will break them down, making them less noticeable in the finished product. However, if you prefer a smoother, seedless sauce, you can easily strain the blended tomatoes through a food mill or fine-mesh sieve before canning. This will remove the skins and seeds, resulting in a smoother texture and a more refined final product.

What type of blender is best for canning tomatoes?

While almost any blender can be used for canning tomatoes, a high-powered blender or immersion blender (also known as a stick blender) is typically the most efficient. High-powered blenders can quickly and easily pulverize large quantities of tomatoes, creating a smooth puree in a matter of seconds. This is particularly helpful when processing large batches for canning, as it significantly reduces preparation time.

An immersion blender offers the advantage of blending directly in the pot, minimizing cleanup and making it easier to process large batches of tomatoes. It is especially useful when blanching tomatoes, as you can blend them directly in the hot water, reducing the risk of splashes and burns. However, regardless of the type of blender you choose, ensure it is clean and in good working condition before beginning the canning process.

How do I acidify my blended tomato mixture for canning?

Acidifying your blended tomato mixture is crucial for safe canning, as it lowers the pH level and inhibits the growth of harmful bacteria, such as Clostridium botulinum. The recommended method is to add either bottled lemon juice or citric acid to each jar before filling them with the tomato mixture. Bottled lemon juice is preferred over fresh lemon juice because its acidity level is consistent, whereas the acidity of fresh lemons can vary.

The amount of lemon juice or citric acid needed depends on the size of the jar and the specific recipe you are using. Generally, for pint jars, you would add 1 tablespoon of bottled lemon juice or ¼ teaspoon of citric acid. For quart jars, use 2 tablespoons of bottled lemon juice or ½ teaspoon of citric acid. Always add the acid directly to the jar before adding the tomato mixture to ensure thorough mixing and proper acidification.

What are some common mistakes to avoid when canning blended tomatoes?

One common mistake is failing to properly acidify the tomato mixture. As mentioned earlier, adding lemon juice or citric acid is essential for safety. Another common mistake is not leaving enough headspace in the jars. Insufficient headspace can lead to siphoning during processing, where the liquid leaks out of the jars, potentially causing seal failures or creating a mess in your canner. Always leave the recommended headspace specified in your canning recipe.

Another error is not processing the jars for the correct time. Insufficient processing can result in incomplete sterilization and potentially lead to spoilage. Always consult a reputable canning resource like the USDA Complete Guide to Home Canning for the appropriate processing times based on your altitude and the size of your jars. Finally, using damaged or improperly sealed jars can compromise the safety of your canned tomatoes. Ensure your jars are free of cracks and chips and that the lids are new and properly fitted before processing.

How long will canned blended tomatoes last?

Properly canned blended tomatoes, processed according to approved guidelines, should last for at least one year, and potentially longer if stored in a cool, dark, and dry place. It’s important to note that while the tomatoes might still be safe to eat after a year, their quality may start to decline in terms of flavor and texture. Therefore, it’s best to use them within 12-18 months for optimal quality.

Always visually inspect the jars before using your home-canned tomatoes. Look for signs of spoilage, such as bulging lids, leaking seals, or any unusual discoloration or cloudiness in the contents. If you notice any of these signs, discard the jar without tasting the contents. If everything looks normal, listen for a whooshing sound when you open the jar, indicating a proper vacuum seal. If there’s no whoosh, or if anything seems off, err on the side of caution and discard the contents.