Home canning is a fantastic way to preserve the delicious taste of summer tomatoes and enjoy them year-round. However, safety is paramount, and proper processing times are crucial to prevent spoilage and, more importantly, botulism, a severe form of food poisoning. Understanding how long to water bath your tomatoes is the cornerstone of safe and successful home canning. This comprehensive guide will walk you through everything you need to know to ensure your canned tomatoes are both delicious and safe to eat.
Understanding the Importance of Processing Time
The goal of water bath canning is to heat the food inside the jars to a temperature high enough to destroy harmful microorganisms, including Clostridium botulinum spores, which can thrive in anaerobic environments like sealed jars. Processing time is the duration for which you maintain this high temperature. Insufficient processing can leave these microorganisms alive, leading to spoilage or, worse, botulism.
The acidity of the food plays a significant role in determining the processing method and time. Tomatoes, while often considered acidic, can vary significantly in their acidity levels. Therefore, it’s essential to treat them as low-acid foods requiring acidification.
Factors Affecting Processing Time
Several factors influence the necessary processing time for water bath canning tomatoes:
- Acidity Level: The natural acidity of your tomatoes is the most critical factor.
- Jar Size: Larger jars require longer processing times to ensure the heat penetrates to the center.
- Altitude: At higher altitudes, water boils at lower temperatures, requiring longer processing times.
- Recipe: Different recipes, especially those including low-acid ingredients, may necessitate longer processing times.
- Whether tomatoes are whole, crushed, or sauced: Different densities require different processing times.
Acidifying Your Tomatoes: A Critical Step
Because the acidity of tomatoes can vary, it’s essential to add acid to each jar before processing to ensure safety. This can be done using lemon juice, citric acid, or vinegar. This acidification process is non-negotiable for safe water bath canning of tomatoes.
How to Acidify Tomatoes
The recommended amounts of acid to add per jar are:
- Lemon Juice: Use bottled lemon juice for consistent acidity. Add 2 tablespoons to each quart jar or 1 tablespoon to each pint jar.
- Citric Acid: Add ¼ teaspoon to each quart jar or ⅛ teaspoon to each pint jar.
- Vinegar: Use 5% acidity vinegar (either white distilled or apple cider vinegar). Add 4 tablespoons to each quart jar or 2 tablespoons to each pint jar. Note that vinegar can alter the flavor of your tomatoes more noticeably than lemon juice or citric acid.
Always add the acid directly to the jar before adding the tomatoes.
Water Bath Canning Essentials: Equipment and Preparation
Before you begin, gather all the necessary equipment and prepare your ingredients. Having everything ready will make the process smoother and safer.
Essential Equipment
- Water Bath Canner: A large pot with a rack to keep jars from sitting directly on the bottom.
- Canning Jars: Use jars specifically designed for canning. Inspect them for chips or cracks.
- Lids and Bands: Use new lids each time and inspect bands for rust or damage.
- Jar Lifter: A tool for safely lifting hot jars.
- Wide-Mouth Funnel: Helps prevent spills when filling jars.
- Ladle: For transferring hot tomatoes into jars.
- Bubble Remover/Headspace Tool: A plastic or wooden utensil for removing air bubbles and measuring headspace.
Preparing Your Tomatoes
Wash your tomatoes thoroughly under running water. Remove any blemishes or bruised spots. Depending on your recipe, you may need to peel the tomatoes.
To peel tomatoes easily:
- Bring a large pot of water to a boil.
- Score an “X” on the bottom of each tomato.
- Place the tomatoes in the boiling water for 30-60 seconds, or until the skins begin to crack.
- Immediately transfer the tomatoes to a bowl of ice water to stop the cooking process.
- The skins should now slip off easily.
Processing Times for Water Bath Canning Tomatoes
The following processing times are based on using acidified tomatoes in a water bath canner. Always refer to a tested and approved canning recipe from a reputable source like the USDA Complete Guide to Home Canning or your local extension office.
Processing times vary depending on whether tomatoes are whole, crushed, or made into sauce, and also depend on the jar size. The tables below provide general guidance, but always consult a specific recipe for the most accurate information.
Processing Times for Whole or Halved Tomatoes (Acidified)
| Jar Size | 0-1,000 ft | 1,001-3,000 ft | 3,001-6,000 ft | 6,001+ ft |
|———-|————-|—————–|—————–|————|
| Pint | 85 minutes | 90 minutes | 95 minutes | 100 minutes|
| Quart | 85 minutes | 90 minutes | 95 minutes | 100 minutes|
Processing Times for Crushed Tomatoes (Acidified)
| Jar Size | 0-1,000 ft | 1,001-3,000 ft | 3,001-6,000 ft | 6,001+ ft |
|———-|————-|—————–|—————–|————|
| Pint | 40 minutes | 45 minutes | 50 minutes | 55 minutes |
| Quart | 45 minutes | 50 minutes | 55 minutes | 60 minutes |
Processing Times for Tomato Sauce (Acidified)
| Jar Size | 0-1,000 ft | 1,001-3,000 ft | 3,001-6,000 ft | 6,001+ ft |
|———-|————-|—————–|—————–|————|
| Pint | 35 minutes | 40 minutes | 45 minutes | 50 minutes |
| Quart | 40 minutes | 45 minutes | 50 minutes | 55 minutes |
Altitude Adjustments: It is very important to adjust processing times for altitude. As altitude increases, the boiling point of water decreases. This means that the water will not reach as high a temperature as it would at sea level, so it is important to process for a longer period of time to properly kill harmful bacteria.
Step-by-Step Water Bath Canning Process
Follow these steps carefully to ensure safe and successful water bath canning:
- Prepare Jars and Lids: Wash jars in hot, soapy water and rinse well. Keep jars hot until ready to fill. You can sterilize them by boiling them for 10 minutes, but it’s not always necessary if you’re processing for 10 minutes or more. Heat lids in hot (not boiling) water to soften the sealing compound.
- Fill Jars: Add the appropriate amount of acid (lemon juice, citric acid, or vinegar) to each jar. Fill jars with prepared tomatoes, leaving the specified headspace (usually ½ inch).
- Remove Air Bubbles: Use a bubble remover or plastic utensil to release trapped air bubbles. Gently tap the jar on the counter.
- Adjust Headspace: If necessary, add more tomatoes to achieve the correct headspace.
- Wipe Jar Rims: Clean the jar rims with a damp cloth to ensure a good seal.
- Place Lids and Bands: Center a lid on each jar and screw on a band until fingertip tight (not too tight).
- Load Canner: Place jars in the water bath canner on the rack. Ensure the water covers the jars by at least 1 inch.
- Process: Bring the water to a rolling boil. Once boiling, start the timer and process for the required time according to your recipe and altitude.
- Turn Off Heat and Cool: Turn off the heat and remove the lid. Let the jars sit in the canner for 5 minutes. This helps prevent siphoning.
- Remove Jars: Using a jar lifter, carefully remove the jars from the canner and place them on a towel-lined surface, leaving space between them.
- Cool and Check Seals: Let the jars cool undisturbed for 12-24 hours. As they cool, you should hear a popping sound as the lids seal.
- Test Seals: After 24 hours, check the seals. Press down on the center of each lid. If the lid doesn’t flex or pop back up, it’s sealed. You can also remove the band and lift the jar by the lid. If the lid stays on tight, it’s sealed.
- Store Properly: Remove the bands (you can reuse them). Wash the jars and label them with the date and contents. Store in a cool, dark, and dry place.
Troubleshooting Common Canning Issues
Even with careful preparation, canning issues can arise. Here are some common problems and their solutions:
- Siphoning: This occurs when liquid escapes from the jar during processing. Ensure proper headspace, avoid overfilling, and allow the jars to cool in the canner for 5 minutes after processing.
- Seal Failure: This can be caused by improper headspace, dirty jar rims, damaged lids, or insufficient processing time. Use new lids each time, ensure clean jar rims, and follow processing times carefully. If a jar doesn’t seal, you can reprocess it with a new lid within 24 hours or refrigerate it and use the contents within a few days.
- Cloudy Liquid: This can be caused by minerals in hard water or starch from the tomatoes. It doesn’t necessarily mean the food is unsafe, but using distilled water and removing excess starch can help.
- Mold: If you see any signs of mold, discard the contents immediately. Never taste or use food from a jar with mold.
Safety First: Recognizing and Preventing Botulism
Botulism is a severe and potentially fatal illness caused by the bacterium Clostridium botulinum. It’s crucial to understand how to prevent botulism when home canning.
Preventing Botulism:
- Always acidify tomatoes: As mentioned earlier, adding acid is crucial for safe water bath canning.
- Follow tested recipes: Use recipes from reputable sources and follow them precisely.
- Process for the correct time: Ensure you process jars for the recommended time based on jar size, altitude, and recipe.
- Check for signs of spoilage: Before opening a jar, inspect it for signs of spoilage, such as bulging lids, leaking, or unusual odors.
Signs of Botulism:
Do not consume food from jars showing any of the following signs of spoilage:
- Bulging lid
- Unusual odor
- Mold growth
- Liquid spurting out when opened
If you suspect botulism, discard the food immediately without tasting it. Contact your local health department or seek medical attention.
Beyond the Basics: Tips for Successful Tomato Canning
- Use high-quality tomatoes: Choose ripe, firm tomatoes for the best flavor and texture.
- Consider adding herbs and spices: Enhance the flavor of your canned tomatoes with herbs like basil, oregano, or thyme, or spices like garlic, onions, or peppers.
- Don’t overpack jars: Leave the specified headspace to allow for proper expansion during processing.
- Keep accurate records: Label your jars with the date and contents. Keep a record of your canning batches, including the recipe used, processing time, and any issues encountered.
Enjoying Your Home-Canned Tomatoes
Once you’ve successfully canned your tomatoes, you can enjoy them in a variety of ways:
- Pasta sauce: Use canned tomatoes as the base for homemade pasta sauce.
- Soups and stews: Add canned tomatoes to soups, stews, and chili.
- Salsa: Make fresh salsa with canned tomatoes.
- Pizza sauce: Use canned tomatoes to make homemade pizza sauce.
- Tomato juice: Blend canned tomatoes for a refreshing tomato juice.
By following these guidelines and paying close attention to detail, you can safely and successfully water bath can your tomatoes and enjoy the taste of summer all year long. Remember to always prioritize safety and consult reliable sources for accurate information.
Why is water bath canning necessary for tomatoes?
Tomatoes are a borderline high-acid food, and their acidity levels can vary depending on the variety and growing conditions. Water bath canning, which uses boiling water to create a vacuum seal, is essential for eliminating molds, yeasts, and enzymes that can cause spoilage in these higher-acid foods. If the acidity is not high enough, dangerous bacteria like Clostridium botulinum, which causes botulism, can survive and thrive in the sealed jars.
Water bath canning works because the high heat of boiling water effectively destroys these spoilage organisms in acidic environments. By properly processing tomatoes in a boiling water bath, you create a safe, shelf-stable product that can be enjoyed for months to come without the risk of foodborne illness.
How do I determine the correct processing time for water bath canning tomatoes?
The correct processing time depends primarily on two factors: the size of the jars you are using and your altitude. Smaller jars will require less processing time than larger jars because the heat penetrates more quickly. Similarly, higher altitudes require longer processing times because water boils at a lower temperature, making it less effective at killing bacteria.
Consult a reliable source, such as the USDA Complete Guide to Home Canning, for specific processing times based on jar size and altitude. It is crucial to follow these guidelines precisely to ensure that the tomatoes are adequately processed and safe for consumption. Never deviate from the recommended times.
What happens if I under-process my tomatoes during water bath canning?
Under-processing tomatoes during water bath canning can lead to several problems, the most serious of which is the potential for botulism. If the tomatoes are not heated to a high enough temperature for a sufficient amount of time, Clostridium botulinum spores can survive and produce a deadly toxin in the sealed jars.
In addition to the risk of botulism, under-processing can also result in spoilage caused by other microorganisms. This can manifest as mold growth, bulging lids, or an off-putting odor or appearance when the jar is opened. Discard any jars of tomatoes that show signs of spoilage, even if they are not visibly spoiled, if you suspect they were under-processed.
Can I reduce the processing time if I add lemon juice or citric acid to my tomatoes?
Adding lemon juice or citric acid to tomatoes is recommended to ensure sufficient acidity for safe water bath canning, especially with modern hybrid varieties that may have lower acidity. These additions do not, however, allow you to reduce the recommended processing time.
The processing time is determined by factors such as jar size, altitude, and the overall density of the food being canned. While the added acidity ensures that the environment is hostile to Clostridium botulinum, the full processing time is still necessary to achieve proper heat penetration and eliminate other spoilage organisms. Always follow the recommended processing times for your jar size and altitude, regardless of the acidity adjustments you make.
What size pot should I use for water bath canning tomatoes?
You need a pot large enough to completely submerge your jars by at least 1-2 inches of water. The pot should also have a rack at the bottom to prevent the jars from sitting directly on the heat source, which can cause them to break.
A designated canning pot is ideal, but any large stockpot that meets these requirements will work. Ensure the pot is wide enough to accommodate the number of jars you plan to process at one time, allowing for adequate space between them to ensure even heating. Crowding the jars can impede water circulation and lead to uneven processing.
How do I know if my tomato jars have sealed properly after water bath canning?
After the jars have cooled completely (usually 12-24 hours), check the lids to ensure they have sealed properly. A properly sealed lid will be concave, meaning it curves slightly downward in the center. When you press on the center of the lid, it should not flex or make a popping sound.
If a lid does not seal, you have a few options. You can either reprocess the tomatoes with a new lid within 24 hours, or you can refrigerate the tomatoes and use them within a few days. Do not store unsealed jars at room temperature, as they are not shelf-stable and are susceptible to spoilage.
What if my tomatoes are floating in the jar after processing?
Tomato separation and floating are common occurrences in home-canned tomatoes and do not necessarily indicate spoilage or a safety issue. This can happen due to variations in tomato density and the release of moisture during processing.
While floating tomatoes may not be aesthetically pleasing, they are still safe to eat as long as the jars have sealed properly and show no other signs of spoilage. To minimize floating, avoid overfilling the jars, pack tomatoes firmly but gently, and ensure adequate headspace. You can also try shaking the jar gently before using the tomatoes to redistribute them.