How to Can Tomato Paste in Canada (Bernardin Method)
To safely can tomato paste in Canada, acidify every jar with bottled lemon juice or citric acid, the same as any tomato recipe, and use the small jar size (usually 125 mL) and processing time your tested Bernardin recipe lists. Paste is very thick, so heat penetrates slowly — the small jar and the tested time are what keep it safe. Cook sieved tomatoes down for a few hours until spreadably thick, add lemon juice to each jar, leave 1 cm headspace, and water-bath process per your Bernardin recipe. The easiest alternative is to skip canning and freeze the paste in tablespoon portions.
Tomato paste is the most concentrated thing you can make from a tomato — and the most divisive to can. Some Canadian preservers love a shelf full of little jars; plenty of others decide, halfway through the third hour of stirring, that they’ll just freeze it next time. Both camps are right. This guide covers the water-bath method following Bernardin, and the freezer shortcut, so you can pick.
Per our food-safety policy, we cite Bernardin for the exact acidifier amount, jar size, and processing time rather than reprinting them — keep your edition open beside this page.
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Two safety points, not one
Every tomato recipe needs acidifying, and paste is no exception:
Add bottled lemon juice (or citric acid) to every jar — the amount your tested recipe lists.
But paste adds a second wrinkle the thinner tomato products don’t have: it’s dense, so heat travels through it slowly. Bernardin’s tested paste recipe handles this by using a small jar (usually 125 mL) and a specific, longer processing time. Both matter:
- Don’t size up to bigger jars — the centre may not reach a safe temperature in the tested time.
- Don’t shorten the processing time to save the stove.
If either of those makes you nervous, that’s a fair instinct — jump to the freezer method below, which sidesteps both.
What you need
- About 5.5 kg (12 lb) ripe paste tomatoes — Roma or San Marzano; you’ll get only 4–5 small jars from this, because paste is mostly evaporated water
- A food mill or fine sieve, and a wide, heavy-bottomed pot (thin pots scorch)
- 125 mL Bernardin jars with new SNAP lids
- Bottled lemon juice OR food-grade citric acid
Sieves the skins and seeds out for a smooth paste, no peeling. Three discs also handle applesauce and berry jam. The default Canadian pick for a tomato glut.
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The method (a slow afternoon)
- Sieve. Simmer quartered tomatoes until soft, then run through a food mill to remove skins and seeds.
- Reduce — slowly. Return the purée to a wide pot and simmer gently, stirring often, until it’s thick enough to mound and hold its shape on a spoon. Budget 2–4 hours; stir more the thicker it gets. A low oven finishes it without scorching.
- Acidify each jar. Bottled lemon juice or citric acid into every hot 125 mL jar, in the amount your recipe lists.
- Fill. Pack the hot paste in, pressing out air pockets, leaving 1 cm (½ inch) headspace. Wipe rims, apply fresh SNAP lids fingertip-tight.
- Process in the boiling water bath for the time in your Bernardin edition for tomato paste, at your altitude band. Time starts at a full rolling boil.
- Cool and check. Rest 5 minutes in the canner, lift to a towel, and leave 12–24 hours before checking seals.
Freeze it instead
The honest shortcut: freeze the paste and skip canning entirely. Since you use paste a spoonful at a time, this is often the better call.
- Reduce the tomatoes to paste exactly as above.
- Spoon into an ice-cube tray (about 1 tbsp per well) and freeze solid.
- Pop the cubes into a labelled freezer bag. Grab one cube per recipe.
No canner, no acidification math, no heat-penetration worry — see how to freeze tomatoes for the full freezing approach.
Related tomato guides
Frequently asked questions
Is it safe to water-bath can tomato paste?
Yes, with a tested recipe — but paste has two safety wrinkles. First, like all tomatoes it must be acidified: bottled lemon juice (or citric acid) in every jar. Second, paste is dense, so heat penetrates slowly; Bernardin's tested recipe uses a small jar (usually 125 mL) and a specific, longer processing time to compensate. Don't scale up to bigger jars or shorten the time — both can leave the centre under-processed. If that feels fussy, freezing is the safe, simple alternative.
Isn't it easier to just freeze tomato paste?
For most households, yes. Paste is used a tablespoon or two at a time, so freezing it in an ice-cube tray and popping the cubes into a freezer bag is faster, needs no canner, and skips the acidification and heat-penetration concerns entirely. Can paste if you want shelf-stable jars and no freezer space; freeze it if you just want it handy. Both are legitimate.
How many tomatoes does it take to make paste?
A lot — paste is the most concentrated tomato product there is. Expect roughly 5–6 kg (11–13 lb) of tomatoes to cook down to only 4–5 small jars, because you're evaporating most of the water. Start with paste tomatoes (Roma, San Marzano) rather than watery field tomatoes; they have more flesh and less water, so the reduction is shorter and the yield higher.
Why is my paste scorching on the bottom?
As tomato paste thickens it sticks and scorches easily. Use a wide, heavy-bottomed pot, keep the heat gentle, and stir often as it reduces — more often the thicker it gets. Some Canadian canners finish the reduction in a low oven (spread on a large pan, stirred occasionally) to avoid stovetop scorching. Whichever way, it's a slow project — budget a few hours.
Sources
- Bernardin Complete Book of Home Preserving (latest edition)
- Health Canada — Food safety for home canning