If you want to try canning tomato sauce, there are important rules to keep in mind for safety. Here’s how to make tomato sauce that’s safe to can and super delicious.
Well, well, well. For anyone who doubted your potential to grow your own tomatoes, you sure showed them. But now you have a dump truck full of ripe, scrumptious, juicy fruit which is gonna go bad in (checks watch) a week or so from now. So, what to do with your bounty?
Prepare a sauce and can it!
“[Canning] is an enjoyable, easy, and economical way to preserve a surplus of ingredients at the peak of their freshness and nutrition,” says Hana van der Steur, Assistant Director of the Institute of Domestic Technology. The culinary ethos of the Southern California-based “food crafting think tank” is reflected in “The New Homemade Kitchen,” the recently released book exploring all manner of food preservation, written by the institute’s late founder Joseph Shuldiner.
The New Homemade Kitchen, $23.49 from Amazon
Institute of Domestic Technology founder Joseph Shuldiner offers his expertise on canning and other food preservation methods.
Below, van der Steur shares her expertise (with a hat tip to Shuldiner) when it comes to the art of cooking and canning tomatoes and tomato sauce.
Related Reading: 5 Tomato Plant Care Tips to Maximize Your Harvest
Heat and acid are two critical components to safely canning tomato sauce.
Starting with acid, whether they’re crops from your backyard garden or an impressive haul of heirlooms from the farmer’s market, tomatoes tend to contain too much alkaline for canning purposes. A lack of acidity and oxygen creates an environment that Clostridium botulinum finds quite hospitable. (Ingesting the bacterium leads to the deeply unpleasant form of food poisoning known as botulism.)
Van der Steur stresses that citric acid is necessary to ensure that your canned tomatoes have enough acidity to deter any bacterial growth. Another solution is commercially packaged lemon juice, which has acidity levels that must meet FDA standards and is appropriate for tomato canning purposes. Be advised that if you choose to use freshly squeezed lemon juice, there’s no guarantee that it will contain enough acidity to balance your recipe.
Simply sealing up cooked tomatoes and calling it a day just won’t do. You need to bring the heat.
“A boiling water bath helps to kill microorganisms that cause food spoilage by raising the temperature beyond what they can tolerate for an extended period of time,” notes van der Steur.
Related Reading: A Beginner’s Guide to Canning
Van der Steur recommends the following items as the bare essentials to a home canning system:
- Glass jars: It may be called canning, but glass jars are the container of choice to store your sauce. “Always inspect jars for chips and cracks before filling and submerging in boiling water,” van der Steur urges. She also notes that the jars themselves can be sanitized and reused many times, but recommends replacing the lids for each fresh batch. Decide whether a quart jar or pint jar makes the most sense for your sauce needs (you’ll need multiple jars of either size for this recipe, but think about how much you tend to use at a time).
Weck 19.6-Ounce Jars, 6 for $39.95 from Williams Sonoma
An alternative to the usual mason jar.
- Preserving pan: “You’ll need a wide, shallow, heavy-bottomed, and non-reactive pan for cooking down the tomatoes,” per van der Steur. While you can use a standard large stockpot to cook the tomatoes you intend to jar, the tall cylindrical shape isn’t as conducive for a quick process and can often impart an undesirable metallic flavor.
- Large stockpot: A full-sized water bath canner is ideal, but if you’re using a standard large stockpot, just be sure that it’s tall enough to accommodate your jars. You’ll need an inch of space on the bottom for the canning rack (see below) and several inches above the jars.
Water Bath Canner, $99.95 from Williams Sonoma
This model includes a double-sided rack, tempered glass lid with steam vent, and a built-in temperature indicator.
- Canning rack: This is placed at the bottom of your water bath to ensure an inch of space between the base of the container and your jars so that the boiling water can completely circulate all the way around the surface area.
- Jar lifter: Those jars are going to be hot, hot, hot. Jar lifters will help you remove them safely from the water bath.
- Food mill: A simple mechanical food mill will even out the texture of your tomato sauce by sifting out seeds and tenderizing pulpy flesh.
- Tomatoes!: Roma tomatoes are the standard, but throwing heirlooms into the mix will add more depth and complexity, truly setting your canned goods apart from what you’d find in the aisles of your local grocery store.
Related Reading: Essential Canning Supplies to Preserve All Your Summer Produce
If you’re new to canning, van der Steur recommends doing a test batch to become familiar with the process. It’s one thing to err with a few pounds of fruits or veggies. It’s quite another to botch an entire season’s harvest.
“We love to tinker in the kitchen and normally encourage our students to get creative with flavor profiles and ingredients—except when it comes to canning,” cautions van der Steur.
Related Reading: 17 Canning Recipes to Capture Peak Season Produce
Keep It Simple
While it may be tempting to season your sauce before jarring it, van der Steur advises against it. Adding herbs and spices will tweak those precious pH levels and potentially invite unwanted bacteria that would render the sauce inedible.
“We recommend ‘doctoring’ your home canned tomato sauce by simmering it with herbs and other aromatics just before using,” says van der Steur.
So, save the basil, garlic, olive oil, and all other add-ins until you’re ready to eat! (That includes meat too; if you want a canned spaghetti sauce with any of these ingredients already added, look for a specific recipe from a trusted source, and if you’re making a meaty spaghetti sauce recipe, be sure you have a pressure canner.)
Related Reading: What Is the Difference Between Pomodoro and Marinara Sauce?
Store It Properly
Van der Steur recommends keeping your sauce in a cool, dark place (like a pantry).
Be sure to inspect the jar before you open it to see if the seal has broken or if there are any visible signs of spoilage. If you’re even a little bit unsure, don’t eat it.
Once canned, you can store your homemade tomato sauce for up to a year, so you’ll have plenty of opportunities to enjoy the fruits of your labor until the next harvest.
Home Canned Tomato Sauce Recipe
Now that you have the knowledge and equipment, it’s time to make your own sauce. Just follow these simple steps and get cooking!
Note: You may notice there’s no mention of sterilized jars; since this canning recipe processes the sauce for more than 10 minutes, you don’t have to sterilize the mason jars ahead of time, but you should still be sure to wash tomatoes, hands, utensils, etc. before you begin.
Home Canned Tomato Sauce
- 2 tablespoons bottled lemon juice or ½ teaspoon citric acid
- 1 teaspoon kosher salt (optional)
- 6 1/2 to 7 pounds (3 to 3.2 kg) firm, ripe tomatoes
- Prepare the jars and canning equipment, fill the water bath canner with water, and begin heating.
- To each prepared 1 pint (500 ml) jar, add 1 tablespoon of the lemon juice (or ¼ teaspoon citric acid) and ½ teaspoon of the salt, if using. For a 1 quart (1 liter) jar, add 2 tablespoons of lemon juice (or ½ teaspoon citric acid) and 1 teaspoon of salt, if using.
- Use a sharp knife to remove any blemishes from the tomatoes and cut them into quarters, then place in a large, nonreactive saucepan over high heat, crushing the tomatoes with a potato masher to release their juices, and bring to a boil. Stir with a wooden spoon to prevent scorching. When the tomatoes come to a boil, reduce the heat to medium- low and simmer gently for 5 minutes to soften.
- Transfer the mixture to a food mill set over a large bowl and run it through the mill until only the peels and seeds remain. Discard the solids. Return the tomato juice to the saucepan and bring to a boil, then lower the heat and simmer until the sauce is very thick, and the volume has reduced by half. Stir frequently to prevent scorching.
- When the volume is reduced by half, pack the jars. Follow steps 6 through 8 of the tomato juice recipe, preceding, leaving ¼ inch (6 mm) of headspace. Process 35 minutes for pint (500 ml) jars or 40 minutes for quarts (1 liter).
Reprinted from “The New Homemade Kitchen” by Joseph Shuldiner with permission by Chronicle Books, 2020
Header image courtesy of fcafotodigital / E+ / Getty Images