Canning tomatoes is a rewarding way to preserve the vibrant flavors of summer and enjoy them throughout the year. This comprehensive guide provides everything you need to know about safely canning fresh tomatoes using the water bath method. We’ll cover everything from selecting the right tomatoes to ensuring proper sealing for long-term storage.
Understanding the Importance of Acidity
Tomatoes, while seemingly acidic, often require an added acid during the canning process to ensure safety. This is because the acidity of tomatoes can vary depending on the variety and growing conditions. Low-acid foods, when not properly processed, can create an environment conducive to the growth of Clostridium botulinum, the bacteria that causes botulism.
To prevent this, we add either lemon juice, citric acid, or vinegar to each jar before processing. The amount of acid added depends on the type of acid used and the size of the jar. It is critical to follow recommended guidelines for acidification to ensure the safety of your canned tomatoes.
Essential Equipment for Water Bath Canning
Before you begin, gather all the necessary equipment. Having everything on hand will make the canning process smoother and more efficient. Investing in quality equipment is a worthwhile investment if you plan to can regularly.
- Water Bath Canner: This is a large pot with a rack that fits inside. The rack is essential to keep the jars off the bottom of the pot, allowing for even heat distribution.
- Canning Jars: Use only jars specifically designed for canning. These jars are tempered to withstand the high temperatures of the canning process. Choose the appropriate size for your needs (pints or quarts).
- Lids and Rings: New lids are required for each canning session to ensure a proper seal. Rings can be reused as long as they are in good condition.
- Jar Lifter: This tool is essential for safely lifting hot jars in and out of the canner.
- Lid Wand: This magnetic wand helps you lift sterilized lids from the hot water.
- Wide-Mouth Funnel: A funnel makes it easier to fill the jars without making a mess.
- Bubble Remover/Headspace Tool: This tool is used to release trapped air bubbles from the jars and measure the headspace (the space between the top of the food and the lid).
- Large Pots: For blanching tomatoes and heating the lids.
- Sharp Knife: For prepping the tomatoes.
- Clean Kitchen Towels: For wiping jars and cleaning up spills.
Selecting and Preparing Your Tomatoes
The quality of your canned tomatoes starts with the tomatoes you choose. Select ripe, firm, and unblemished tomatoes for the best results. Avoid using tomatoes that are bruised, damaged, or show signs of spoilage.
Consider using varieties specifically bred for canning, such as Roma, San Marzano, or Amish Paste. These varieties have a lower water content and a higher solids content, resulting in a thicker and more flavorful canned product.
Before you begin, wash the tomatoes thoroughly under cool running water. Remove any stems or leaves.
Peeling the Tomatoes: Two Effective Methods
Peeling tomatoes is essential for a smooth and appealing canned product. Here are two common methods for peeling tomatoes:
- Blanching: Bring a large pot of water to a boil. Cut a shallow “X” on the bottom of each tomato. Carefully drop the tomatoes into the boiling water for 30-60 seconds, or until the skin starts to split. Immediately transfer the tomatoes to a bowl of ice water to stop the cooking process. The skins should slip off easily with a paring knife.
- Freezing (for later use): Place unpeeled tomatoes in freezer-safe bags or containers and freeze. When ready to use, thaw the tomatoes slightly. The skins will slip off easily. This method works well if you don’t have time to can the tomatoes immediately.
Preparing the Tomatoes for Canning
After peeling, you can choose to leave the tomatoes whole, quarter them, or crush them. The method you choose will depend on your personal preference and how you plan to use the canned tomatoes.
If you are using larger tomatoes, you may want to remove the core. To do this, simply cut a cone-shaped piece from the top of the tomato.
The Water Bath Canning Process: Step-by-Step
Now that you have your equipment and your tomatoes are prepped, it’s time to start the canning process.
Step 1: Sterilizing the Jars
Sterilizing the jars is crucial to eliminate any bacteria or microorganisms that could cause spoilage.
Place the jars in the water bath canner, ensuring they are completely submerged in water. Bring the water to a boil and boil for 10 minutes. If you live at an altitude above 1,000 feet, add one minute of boiling time for each 1,000 feet of altitude.
Keep the jars hot until you are ready to fill them. You can leave them in the hot water or remove them and place them on a clean towel-lined surface.
Step 2: Preparing the Lids and Rings
While the jars are sterilizing, prepare the lids and rings.
Follow the manufacturer’s instructions for preparing the lids. Typically, this involves simmering the lids in hot (not boiling) water for a few minutes to soften the sealing compound. Do not boil the lids, as this can damage the sealing compound.
Keep the lids hot until you are ready to use them.
Step 3: Adding Acid to the Jars
Before filling the jars with tomatoes, add the appropriate amount of acid to each jar. This is a critical step for safety.
- Lemon Juice: Use bottled lemon juice, as the acidity level is consistent. Add 2 tablespoons of lemon juice to each quart jar or 1 tablespoon to each pint jar.
- Citric Acid: Add 1/2 teaspoon of citric acid to each quart jar or 1/4 teaspoon to each pint jar.
- Vinegar: Use 5% acidity white vinegar. Add 4 tablespoons of vinegar to each quart jar or 2 tablespoons to each pint jar. Vinegar can slightly alter the taste of the tomatoes.
Step 4: Filling the Jars
Using a wide-mouth funnel, fill the jars with the prepared tomatoes, leaving the recommended headspace. Headspace is the space between the top of the food and the lid. For tomatoes, the recommended headspace is 1/2 inch.
Pack the tomatoes loosely in the jars. You can add additional ingredients, such as salt, herbs, or spices, at this stage.
- Salt: Optional, but adds flavor. Use canning or pickling salt. Add 1 teaspoon per quart jar or 1/2 teaspoon per pint jar.
- Herbs and Spices: Add dried or fresh herbs and spices to your preference.
Step 5: Removing Air Bubbles and Adjusting Headspace
After filling the jars, use a bubble remover or a clean utensil to release any trapped air bubbles. Gently run the tool around the inside of the jar to dislodge the bubbles.
If necessary, adjust the headspace by adding more tomatoes or removing some of the liquid.
Step 6: Cleaning the Jar Rims
Using a clean, damp cloth, wipe the rims of the jars to remove any food particles or residue. This is essential for ensuring a proper seal.
Step 7: Placing the Lids and Rings
Using a lid wand, carefully place a lid on each jar, ensuring it is centered. Screw on a ring until it is fingertip tight. This means tightening the ring until you feel resistance, then backing off slightly. Do not overtighten the rings.
Step 8: Processing the Jars in the Water Bath Canner
Carefully lower the filled jars into the water bath canner using a jar lifter. Ensure the jars are not touching each other and that they are completely submerged in water. The water level should be at least 1 inch above the tops of the jars.
Bring the water to a rolling boil. Once the water is boiling, begin timing the processing time. The processing time will vary depending on the size of the jars and your altitude.
| Jar Size | Processing Time (0-1,000 ft) | Processing Time (1,001-3,000 ft) | Processing Time (3,001-6,000 ft) | Processing Time (6,001+ ft) |
|---|---|---|---|---|
| Pints | 85 minutes | 90 minutes | 95 minutes | 100 minutes |
| Quarts | 85 minutes | 90 minutes | 95 minutes | 100 minutes |
Adjust processing times according to your altitude. It is crucial to follow recommended processing times to ensure the safety of your canned tomatoes. Underprocessing can lead to spoilage and the risk of botulism.
Step 9: Cooling and Sealing the Jars
After processing for the recommended time, turn off the heat and carefully remove the lid of the canner. Let the jars sit in the hot water for 5 minutes before removing them. This helps to prevent siphoning (the loss of liquid from the jars).
Using a jar lifter, carefully remove the jars from the canner and place them on a towel-lined surface, leaving at least one inch of space between the jars. Avoid placing the jars on a cold surface, as this can cause them to break.
Let the jars cool undisturbed for 12-24 hours. As the jars cool, you should hear a popping sound as the lids seal.
Step 10: Checking the Seals
After the jars have cooled completely, check the seals. The lids should be concave (curved downwards) and should not flex when pressed in the center.
To test the seal, you can also remove the ring and lift the jar by the lid. If the lid stays securely attached, the jar is properly sealed.
Step 11: Labeling and Storing
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 18 months.
Troubleshooting Common Canning Problems
Even with careful attention to detail, canning problems can sometimes occur. Here are some common issues and how to address them:
- Jars Didn’t Seal: If a jar doesn’t seal, you can reprocess it within 24 hours using a new lid. Alternatively, you can refrigerate the tomatoes and use them within a few days.
- Siphoning: Siphoning is the loss of liquid from the jars during processing. This can be caused by overfilling the jars, not removing air bubbles properly, or fluctuations in pressure during processing.
- Cloudy Liquid: Cloudy liquid can be caused by hard water, starch from the tomatoes, or mineral deposits. While cloudy liquid doesn’t necessarily indicate spoilage, it can affect the appearance of the canned tomatoes.
Creative Ways to Use Your Canned Tomatoes
Once you have a pantry full of home-canned tomatoes, the possibilities are endless! Here are just a few ideas:
- Pasta Sauce: Use your canned tomatoes as the base for homemade pasta sauce.
- Soup: Add canned tomatoes to soups and stews for a rich and flavorful base.
- Chili: Canned tomatoes are a staple ingredient in chili recipes.
- Salsa: Make your own fresh salsa using canned tomatoes, onions, peppers, and cilantro.
- Braised Meats: Use canned tomatoes to braise meats for a tender and flavorful dish.
Canning tomatoes is a rewarding skill that allows you to enjoy the taste of summer all year long. By following these guidelines carefully, you can safely and successfully can your own fresh tomatoes and create a delicious and healthy pantry staple. Remember to always prioritize safety and follow recommended procedures to prevent spoilage and ensure the well-being of yourself and your family.
Why is acidity important when canning tomatoes?
Tomatoes are a borderline high-acid food, meaning their natural acidity might not be high enough to prevent the growth of Clostridium botulinum, the bacteria that causes botulism. Botulism is a serious and potentially fatal illness, so ensuring proper acidity is crucial for safe home canning. Adding an acid, such as bottled lemon juice, citric acid, or vinegar, lowers the pH level of the tomatoes, creating an environment where botulism spores cannot grow.
Adding acid is a critical step in the canning process and should not be skipped or altered. Always use the recommended amount of acid specified in tested canning recipes from reputable sources like the USDA or your local extension office. Using the correct amount and type of acid ensures that your canned tomatoes are safe to consume and free from the risk of botulism.
What types of tomatoes are best for canning?
Roma, San Marzano, and other paste-type tomatoes are excellent choices for canning because they have a meaty texture, fewer seeds, and a lower water content compared to other varieties. These characteristics result in a thicker, richer sauce or canned tomato product. Avoid using tomatoes from dead or frost-killed vines as their acidity may be compromised.
However, you can also use other tomato varieties for canning, but it’s important to adjust the processing time accordingly. When using other varieties, consider removing excess water and seeds before canning to improve the texture and prevent the sauce from becoming too thin. Regardless of the variety you choose, ensure the tomatoes are ripe, firm, and free from blemishes or bruises.
How do I prepare my canning jars and lids?
Properly preparing your canning jars and lids is essential for creating an airtight seal, preventing spoilage, and ensuring the long-term safety of your canned tomatoes. Start by thoroughly washing your jars in hot, soapy water and rinsing them well. Then, sterilize the jars by submerging them in boiling water for 10 minutes. Keep the jars hot until you are ready to fill them.
While jars require sterilization, modern canning lids only need to be simmered in hot (not boiling) water before use. This softens the sealing compound and helps create a good seal. Always follow the manufacturer’s instructions for preparing your lids. Never reuse lids, as the sealing compound may be compromised, leading to seal failures.
What does “headspace” mean in canning and why is it important?
Headspace refers to the empty space between the top of the food in the jar and the lid. It’s crucial for creating a proper vacuum seal during the canning process. As the jars cool after processing, the food shrinks, creating a vacuum that pulls the lid down tightly against the jar, forming a seal.
Insufficient headspace can cause the food to expand during processing, pushing the contents out and preventing a proper seal. Too much headspace can result in insufficient vacuum formation, leading to spoilage. Follow the recipe’s specific headspace recommendations (usually 1/2 inch for tomatoes) for optimal results and safe preservation.
How do I know if my canned tomatoes have sealed properly?
After the jars have cooled completely (usually 12-24 hours after processing), check each one to ensure a proper seal. The easiest way to check is by pressing down on the center of the lid. If the lid doesn’t flex or give and remains concave (slightly indented), it’s likely sealed.
Another method is to tap the lid with a spoon. A clear, high-pitched sound indicates a good seal, while a dull, thudding sound suggests the jar didn’t seal properly. If a jar hasn’t sealed, you can either reprocess it with a new lid within 24 hours, store it in the refrigerator and use it within a few days, or freeze the contents.
How long can I store home-canned tomatoes?
Home-canned tomatoes, when processed and sealed correctly, can be safely stored for at least 12-18 months in a cool, dark, and dry place. Over time, the quality of the tomatoes may deteriorate slightly in terms of color and flavor, but they should still be safe to eat as long as the seal remains intact.
Always check the lids for any signs of bulging, leakage, or rust before opening a jar. If any of these are present, discard the jar without tasting the contents. When you open a jar, check for any unusual odors, mold, or discoloration. If anything seems amiss, err on the side of caution and discard the tomatoes.
Can I add herbs and spices to my canned tomatoes?
While adding herbs and spices to your canned tomatoes can enhance the flavor, it’s crucial to follow tested recipes and guidelines for safety. Adding too many ingredients or ingredients that are not specifically approved for canning can affect the acidity and processing time required, potentially leading to spoilage.
It is generally safe to add dried herbs and spices to canned tomatoes, but it’s important to measure them accurately and follow a reputable recipe. Fresh herbs, on the other hand, should be used with caution as they can introduce bacteria and affect the pH level. Always prioritize safety and consult reliable canning resources before experimenting with additions.