How to Can Plain Tomato Sauce in Canada (Bernardin Method)

If how to can tomatoes is the September gateway recipe, tomato sauce is the gateway recipe’s smarter, denser sibling. Same tomatoes, same lemon juice rule, but you strain out skins and seeds and reduce the pulp down to something that drops off a spoon. The result: jars of plain tomato sauce that go into chili, soup, pasta, shakshuka, braises — anywhere “1 can of tomato sauce” appears in a recipe all winter.

This is plain tomato sauce only. The moment you add onions, garlic, herbs, oil, peppers, or meat, the recipe is no longer water-bath safe — that’s the pH rule from the spaghetti sauce article. Pasta sauce with stuff in it = pressure canning. Plain tomato sauce = water-bath canning with lemon juice.

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What you’ll end up with

• About 7 × 500 mL jars from 10 kg (22 lb) of paste tomatoes
• A 50% reduction from raw tomato volume to finished sauce
• Smooth texture — no skins, no seeds
• Sauce thick enough to coat a spoon but still pourable
• Shelf-stable for 12 months in a cool, dark place

10 kg sounds like a lot. A single bushel from a tomato U-pick farm is ~25 kg ($30–40 in late August / September), so think of one canning session as a third of a bushel. Two sessions and your pantry is set.

Equipment you’ll need

The strainer is the part that makes this project realistic. Without it you’re scooping seeds and peeling skins one tomato at a time.

• A food strainer or mill — the single biggest time-saver. Options below.
• A boiling water bath canner (any tall stockpot with a rack)
• 7 × 500 mL Bernardin jars (or 3–4 × 1 L jars) + fresh SNAP lids + bands
• Standard canning kit — jar lifter, headspace tool, funnel, ladle
• A wide heavy-bottomed pot (8 L+) for cooking the sauce down
• Bottled lemon juice — about 120 mL per batch
• A large bowl of ice water for the peel-loosening dip (if not using a Victorio-style strainer)

Three strainer paths, from fastest to slowest

Tool	Type	Blanching needed?	Time for 10 kg	Cost
Victorio Food Strainer (or KitchenAid attachment)	Mechanical, hand-cranked or motor-driven	No — eats raw tomatoes	30 min	$80–250
Manual food mill (OXO, Mouli)	Hand-cranked, cone-shaped	Yes — blanch + peel first	60 min	$40–80
Fine-mesh sieve + wooden spoon	Manual, no moving parts	Yes — blanch + peel first	2+ hours	$15–25

If you can plan ahead and you’re going to can sauce more than one season, the Victorio is worth it. Costs ~$120 in Canada at the Canadian Tire / Lee Valley / Bass Pro tier. Pays itself off in time saved during a single tomato season.

Choose the right tomatoes

• Paste / Roma varieties are the right call: San Marzano, Amish Paste, Roma, Plum. Less juice, more pulp, less reduction needed.
• Beefsteak and slicing tomatoes work but yield 30–40% less sauce per kilo. Use them if that’s what you have, just plan on a longer simmer.
• Cherry and grape tomatoes — skip. Tiny, lots of seeds, terrible yield-to-effort ratio.
• Bruised or split is fine if you cut out the bad spots. Mouldy is not — discard those.

For 10 kg of paste tomatoes you get about 3–4 L of sauce after reduction → ~7 × 500 mL jars.

The method

Step 1: Heat the canner

Fill your water-bath canner with enough water to cover the jars by 2.5 cm. Bring to a simmer. Warm your empty Bernardin jars in the simmering water so they’re hot when you fill them.

Step 2: Process the tomatoes

With a Victorio-style strainer:

1. Wash tomatoes, cut into quarters
2. Feed them into the strainer hopper, crank the handle
3. Pulp drips into one bowl, skins-and-seeds extrude out the other end
4. Done in 20–30 minutes for 10 kg

With a manual food mill:

1. Score each tomato with a shallow X on the bottom
2. Blanch in batches: drop into boiling water for 30–60 seconds until skins crack
3. Plunge into ice water
4. Slip off skins
5. Quarter and core, removing any bruised flesh
6. Run the cores-and-flesh through the food mill into your cooking pot
7. Compost the skins

Either way, you end up with about 5 L of raw, smooth tomato pulp.

Step 3: Reduce the sauce

Tip the pulp into your wide heavy pot. Bring to a gentle simmer (medium-low heat) and reduce uncovered for 1–2 hours, stirring every 10–15 minutes to prevent scorching. The sauce should:

• Reduce by about half (5 L → ~2.5 L)
• Thicken to coat a spoon
• Concentrate to a deep red-orange
• Still pour smoothly (not paste-thick)

You can reduce more if you want a thicker sauce — just don’t add anything else. Plain tomato + heat is the recipe.

Step 4: Acidify each jar

This is the food-safety step that makes plain tomato sauce water-bath safe. Every jar, every time:

• 500 mL jar: 1 tbsp bottled lemon juice
• 1 L jar: 2 tbsp bottled lemon juice

Alternative: ¼ tsp citric acid per 500 mL or ½ tsp per 1 L. Bernardin-approved either way.

Add the lemon juice directly to each empty hot jar before filling. Don’t try to add it to the cooking pot — the per-jar measurement is what guarantees the pH.

Bottled lemon juice only. Fresh lemon juice varies in acidity from lemon to lemon and is not safe here.

Step 5: Fill the jars

Ladle hot sauce into each acidified jar through a wide-mouth funnel. Leave 2 cm (¾ inch) headspace — Bernardin’s standard for tomato products. (More than the 1 cm used for jams; the denser pulp needs the extra room.)

Step 6: Debubble and wipe

Run a non-metallic spatula or chopstick around the inside of each jar to release trapped air. Re-check headspace; top up if needed. Wipe each rim clean with a damp cloth — sticky residue kills the seal.

Step 7: Apply lids and process

Centre a fresh SNAP lid on each jar, apply a band fingertip-tight. Lower jars into the canner with the jar lifter; ensure they’re covered by 2.5 cm of water.

Process for the time printed in your Bernardin recipe at your altitude band. Tomato sauce in 500 mL jars at sea level is typically ~35 minutes; 1 L jars typically ~40 minutes. Use the actual number from your Bernardin edition, and add for altitude per our altitude-adjustments guide. Start timing when the water returns to a full rolling boil.

Step 8: Cool and check seals

Turn off the heat, wait 5 minutes, then transfer jars to a towel-lined counter. Leave undisturbed 12–24 hours. Lids should “ping” as they seal. After cooling, press the centre of each lid — firm and concave means sealed.

If a jar didn’t seal, the 24-hour rule applies.

Storage and use

• Pantry (unopened): 12–18 months best quality
• Opened: refrigerate, use within a week
• Date every jar with a Sharpie on the lid

Plain tomato sauce is the most-used canned good in our test kitchen, behind crushed tomatoes:

• Pasta — heat the sauce, add fresh garlic and basil at the end, toss with pasta
• Chili base — start with sauce, brown beef, add beans and spices
• Shakshuka — sauce + onions + peppers (in the pan, not the jar) + poached eggs
• Soup — tomato soup with sauce + cream + basil
• Braises — add to short ribs, lamb shanks, chicken cacciatore
• Pizza sauce — reduce further with herbs in the pan when you’re making pizza

Common questions

”Can I just use canned grocery-store tomatoes for sauce?”

Yes for the recipe (better flavour for “homemade” sauce in winter from grocery cans than from sad winter tomatoes). No for the canning project — there’s no point canning already-canned tomatoes. The whole point is preserving the fresh August/September harvest.

”My sauce separated in the jar — water on top, pulp on the bottom”

Normal. Stir when you open. Combined with a bulging lid, foam, or off smell, discard the jar.

”Is the lemon juice flavour going to come through?”

No. The 1 tbsp per 500 mL is below the taste threshold once the sauce is finished. You won’t notice it. The pH change matters; the flavour change is invisible.

”What if I want to add basil?”

Add fresh basil when you open and serve the jar, not before canning. Fresh herbs added to the jar pre-canning won’t kill you (basil isn’t pH-destabilizing the way onion is) but they go grey-brown during processing and add nothing to the finished product. Save the basil for the pan.

When to make this

Late August through late September in Canada. Tomato U-pick farms peak around Labour Day; grocery store tomato prices drop in early September. Plan two canning sessions: one for crushed/whole tomatoes (the parent recipe) and one for sauce. The two together stock a household for the year.

Next steps

• How to can tomatoes (crushed and whole) — the chunky parent recipe.
• The pH rule — why you can’t add onions or meat to canned sauce.
• Salsa — the structured exception to that rule.
• Water-bath canning pillar — full method context.
• Canning altitude adjustments — for the minute math.