A tomato basil soup canning recipe is safe only when the jar holds a tested, pourable tomato base and the cream, butter, and thickener stay on the stove until serving day. Once onions, garlic, stock, and basil go in with the tomatoes, the mixture is a low-acid soup. Boiling-water canning does not get hot enough to control Clostridium botulinum in that jar. A pressure canner does.
The recipe below follows the roasted tomato basil soup process published from The All New Ball Book of Canning and Preserving. Processing time and pressure are the safety controls. They are not adjustable for a thicker soup or a shorter afternoon.
Why this soup cannot go in a boiling-water canner
Tomatoes sit near the acid boundary used in home canning. A pH of 4.6 or lower keeps botulism bacteria from growing, which is why plain crushed tomatoes and tomato juice can be boiling-water canned after bottled lemon juice or citric acid is added to every jar. Modern varieties, overripe fruit, and tomatoes from frost-killed vines can land above that line, so extension guidance treats acidification as required for those plain products.
Soup is a different product. Onion, garlic, and broth dilute the tomato acid. Ball’s tested roasted tomato basil soup is written for a pressure canner for that reason, and the published process does not call for lemon juice or vinegar in the jar. The compensating control is temperature: a pressure canner holds the food around 240–250°F (116–121°C), which boiling water at 212°F (100°C) cannot do.
Water-bath times from a family recipe, or from a sauce recipe, do not transfer to this soup. A basil-garlic tomato sauce that is acidified and processed as a sauce is not the same formula as a stock-based soup.
What belongs in the jar, and what does not
USDA soup directions and university extensions draw a hard line around ingredients that slow heat moving to the center of the jar. Dairy and starches are the usual problems. Cream can also separate or curdle under long pressure processing, so the jar fails on quality even before the safety question.
| Ingredient | In the canning jar? | Why |
|---|---|---|
| Ripe, sound tomatoes | Yes, in the tested amount | The base of the formula |
| Onion, garlic, basil | Yes, only in the tested amounts | Extra low-acid vegetables change the formula |
| Stock or the wine swap listed below | Yes | Part of the tested liquid |
| Salt and black pepper | Yes, salt to taste | Seasoning does not replace processing |
| Milk, cream, half-and-half, cheese, butter | No | Add when you heat the jar to serve |
| Flour, cornstarch, roux, rice, pasta | No | Thickens the jar and slows heat penetration |
| A fully pureed, pudding-thick soup | No | Can the base pourable; blend or reduce after opening if you want it heavier |
Dried basil can stand in for fresh if that is all you have, but do not increase the herb load to “make up for” dried flavor. Ball’s published notes on this recipe treat basil as optional and allow another mild green herb such as parsley. That is a flavor swap, not a license to add peppers, celery, or carrots.
Tomato basil soup canning recipe
This is the roasted tomato basil soup formula associated with The All New Ball Book of Canning and Preserving, as republished with the book’s processing times. Yield is about 6 pints or 3 quarts. Use plum or paste tomatoes if you can. Slicing or heirloom tomatoes work in the same process if you start with 10 to 12 pounds instead of 8, because they carry more water.
Ingredients
- 8 pounds plum tomatoes, cored and halved (or 10 to 12 pounds slicing or heirloom tomatoes)
- 5 teaspoons salt, divided
- 2 teaspoons ground black pepper, divided
- 1 tablespoon olive oil
- 2 cups diced onion
- 4 cloves garlic, minced
- 1 cup dry white wine
- 4 cups vegetable stock or chicken stock
- 1 cup fresh basil leaves, tightly packed
Wine is for flavor. An equal amount of broth, or water plus 1 tablespoon vinegar, can replace it. Do not add cream at this stage.
Equipment
Pressure canner with a rack, not a pressure cooker and not a boiling-water canner. Dial-gauge canners should be tested for accuracy. You also need pint or quart jars, new lids, bands, a jar lifter, a canning funnel, a bubble remover, and clean towels. An immersion blender is the simplest way to finish the soup. If you use a countertop blender, vent the lid and blend in small batches so hot soup does not erupt.
Method
- Heat the oven to 375°F (190°C). Core the tomatoes, halve them, and scoop out the seed cavities. Place them cut side up, season with part of the salt and pepper, and roast about 45 minutes, until soft and the cut surfaces look dry at the edges. Slip off the skins and chop the flesh coarsely. Juicier tomatoes may need longer roasting so the soup does not finish thin.
- Warm the olive oil in a large pot. Cook the onion, garlic, and remaining salt and pepper over medium heat for 8 to 10 minutes, until fragrant and soft but not browned.
- Add the wine and simmer about 10 minutes, until most of it has cooked off. Add the roasted tomatoes, stock, and basil. Cook about 20 minutes, until heated through. Start preheating the pressure canner while the soup cooks, with the water level your canner manual specifies. Jars should be hot.
- Blend until smooth. Return the soup to the pot and bring it back to a simmer. It should be pourable, not a paste.
- Ladle hot soup into hot jars, leaving 1 inch (2.5 cm) headspace. Slide a bubble remover through the jar, adjust headspace with more hot soup if needed, wipe the rims, and set lids and bands fingertip-tight.
- Load the canner, lock the lid, and vent steam for 10 minutes before you put the weight on or close the petcock. Bring the canner to the pressure in the table below. Start the timer only when that pressure is stable. Process pints 50 minutes or quarts 60 minutes. When time is up, turn off the heat and let the canner drop to zero on its own. Do not run cold water over it or open the vent early. Wait a few minutes after the pressure is gone, then remove the lid away from your face.
- Set jars on a towel with space between them. Leave them 12 to 24 hours. A sealed lid is firm and does not flex. Remove bands, wipe jars, label with the date, and store in a cool, dark place. Refrigerate after opening and use within a few days. Ball’s notes on this recipe cite a quality window of about 12 to 18 months for sealed jars.
If a jar does not seal, refrigerate it and use it within a few days, or reprocess within 24 hours with a new lid for the full original time.
Processing pressure by altitude
Time stays the same at higher elevations. Pressure goes up, because water boils at a lower temperature as elevation increases and the canner needs more pounds to reach a safe internal temperature.
| Elevation | Dial-gauge canner | Weighted-gauge canner |
|---|---|---|
| 0–1,000 ft | 11 lb | 10 lb |
| 1,001–2,000 ft | 11 lb | 15 lb |
| 2,001–4,000 ft | 12 lb | 15 lb |
| 4,001–6,000 ft | 13 lb | 15 lb |
| 6,001–8,000 ft | 14 lb | 15 lb |
Weighted-gauge canners generally jump from 10 pounds to 15 pounds above 1,000 feet. There is no 12-pound setting on a standard three-piece weight. If your gauge reads between marks, use the next higher pressure the canner can hold, not a lower one.
How to turn the jar into the soup you actually want
The canned soup is a concentrated tomato-basil base, not a finished bisque. That is the useful part of the method. One pint plus a little liquid is enough for two bowls.
Heat the soup gently with a splash of stock or water if it thickened in the jar. For a cream-style bowl, warm milk, cream, or a spoon of butter in a separate pan and stir the hot tomato base into the dairy, not the other way around, which reduces curdling. A teaspoon of sugar balances a sharp batch. Cooked rice, croutons, or a grilled cheese sandwich belong on the plate, not in the canning jar.
Mistakes that make an otherwise careful batch unsafe
Changing the solid-to-liquid ratio is the most common drift. Extra onions, a cup of carrots, or a can of beans means you are no longer on the tested formula. The USDA mixed-soup process is a different recipe: jars filled only halfway with solids, liquid to 1 inch headspace, and longer times (60 minutes for pints, 75 minutes for quarts, at the same altitude pressures). It is not a shortcut for this pureed tomato soup.
Other failures show up often in unpublished recipes:
- Processing 20 or 25 minutes because a blog used a short time. This Ball process is 50 minutes for pints and 60 for quarts.
- Packing the soup thicker than the recipe so it “looks like restaurant soup” in the jar.
- Skipping the 10-minute vent. Trapped air keeps the canner from reaching true pressure.
- Force-cooling the canner. Jars can lose liquid, and seals can fail.
- Using tomatoes from dead vines, or fruit with mold or soft rot. Acid and texture are both unpredictable, and damaged tissue is a poor starting point for a shelf-stable food.
- Treating an electric pressure cooker as a pressure canner. Most are not rated for home canning. Use a canner the manufacturer approves for this process, and follow that manual for venting and water level.
Before you store the jars
Check every lid. A broken seal, seepage, rising bubbles, a spurting jar, or an off smell is a discard. Boiling will not reliably make a suspect low-acid jar safe to eat. When in doubt, throw it out without tasting.
Keep jars where they will not freeze and where the temperature stays cool. Heat over time fades basil flavor and can darken the tomatoes. That color change alone is not spoilage. A bulging lid is.
Questions people ask after the first batch
Can I freeze this instead of canning it? Yes. Freezing skips the acidity and heat-penetration limits. Cool the soup, leave headspace in freezer containers, and add cream only after thawing. Frozen tomato soup keeps good quality for several months at 0°F (−18°C).
Can I water-bath can it if I add lemon juice? Not this formula. Added acid does not make an untested broth-and-onion soup safe for a boiling-water canner. Acidified tomato products have their own tested recipes, with their own vegetable limits and times. Use one of those if you do not have a pressure canner, or freeze the soup.
Why does Ball’s process skip lemon juice? Because this specific recipe was developed for pressure canning. That exception belongs to the tested process. It is not a reason to skip acid in crushed tomatoes, tomato juice, or a boiling-water tomato sauce.
The soup separated in the jar. Is it spoiled? Liquid on top and solids below is common in home-canned tomato products. Stir when you heat it. Separation is not the same as a broken seal or an off odor.
Can I double the batch? Yes, if every jar still gets the full processing time and you do not change ratios. Do not fill the canner so tightly that steam cannot move. A partial second load is safer than an overloaded first one.