Pressure Canning

The only safe home method for low-acid foods: vegetables, meats, poultry, fish, beans, and soup. A boiling-water bath cannot reach the temperature needed to kill Clostridium botulinum spores in low-acid foods.

How it works

Pressure canning reaches about 116 °C — high enough to destroy botulism spores. A water-bath at 100 °C cannot. Skipping or shortcutting pressure canning on a low-acid food can be fatal.

When to use this method

Use pressure canning for: green and yellow beans, corn, peas, carrots, beets, mixed vegetables, meats, poultry, fish, broth and stock, dried beans, and low-acid soups (no thickeners or dairy).

Authority sources

How pressure canning preserves food (and why water-bath can't)

Every canned food carries a microbiological risk, and one organism above all sets the rules: Clostridium botulinum. Its spores live everywhere — in soil, on vegetables, on raw meat — and they survive boiling water indefinitely. In a sealed, low-oxygen, low-acid jar at room temperature, those spores germinate, multiply, and produce botulinum toxin, the most lethal substance Health Canada tracks. A teaspoon of jar liquid can be enough.

The only home-kitchen method that destroys C. botulinum spores is heat above 116 °C (240 °F), held for the full processing time of a tested recipe. Water at sea level boils at 100 °C and goes no higher no matter how hard the burner runs — that's why a boiling-water bath cannot make low-acid food safe. Steam under pressure does reach 116 °C, and a pressure canner is the only home appliance built and tested to hold that temperature accurately for an hour or more.

The line between "water-bath safe" and "must be pressure canned" is the food's natural pH. Below 4.6 (fruit, jam, vinegar pickles, properly acidified tomatoes) the acid itself blocks spore growth — water-bath works. At or above 4.6 (every vegetable, every meat, every bean, every plain broth, plain pumpkin) only pressure canning is safe. There is no edition of Grandma's recipe and no quantity of added lemon juice that turns a low-acid food into a water-bath candidate. See the pH rule, in full, and Health Canada's botulism backgrounder for the public-health side.

Pressure canner ≠ pressure cooker

This is the most important equipment distinction in home preserving. A pressure canner is purpose-built for the task: it holds 7 × 1 L jars or 16 × 500 mL jars upright on a rack, reaches and holds the high pressures needed to destroy botulism spores, and has a regulator (weight or dial) calibrated for canning.

A pressure cooker — including the Instant Pot — is not a pressure canner. Most reach lower peak pressures, hold them less precisely, and have not been tested by Bernardin or Health Canada as canning equipment. Some Instant Pot models advertise a "canning" function; Bernardin and Health Canada do not recommend them for canning low-acid foods. Treat the canner and the cooker as two separate purchases. Our Presto vs All American buying guide walks through the two genuine pressure canners worth owning in Canada.

Equipment you need

A genuine pressure canner — common Canadian-available models are Presto (23-quart or 16-quart) and All American (cast aluminum, weighted gauge, lifetime warranty). 23-quart canners hold a full case of 500 mL jars in one batch.
Dial gauge or weighted gauge? Weighted-gauge canners hiss when the pressure is right and require no annual calibration. Dial-gauge canners give a more precise reading but must be tested for accuracy every year at your provincial extension service or a small-appliance repair shop. An out-of-calibration dial gauge is the most common cause of pressure-canning safety failures.
Bernardin jars — most pressure recipes use 500 mL or 1 L. Verify the recipe specifies your jar size; pressure times depend on it. Wide-mouth jars make packing chicken pieces, fish chunks, and stew much easier — see wide-mouth vs regular-mouth.
Fresh SNAP lids for every batch — same single-use rule as water-bath. See SNAP lid reuse rules.
Jar lifter, headspace tool, funnel — same as water-bath canning.
A timer with an alarm. Pressure-canning times can run 25–90 minutes at pressure; do not eyeball it.

See the Canadian canning equipment guides for canner, jar, and tool comparisons in Canadian sizes and prices.

What to pressure can

Every food on this list is low-acid and unsafe for water-bath canning. Pressure canning is the only safe home method.

Plain meats — chicken (raw-pack or hot-pack), beef, pork, ground meat, game.
Stew and soup — beef stew without thickener, chunky vegetable soup. The no-thickener rule (no flour, cornstarch, pasta, or rice) is universal — thickeners block heat penetration and make the process unsafe.
Stocks and broths — bone broth (chicken, beef, or fish). Strained clear broths process faster than chunky soups.
Fish and shellfish — pressure-canned salmon (Pacific or Atlantic), trout, char, tuna. Fish processes longer than meat.
Dried beans — navy, kidney, pinto, black, romano, all Canadian-grown varieties. A jar costs a fraction of a commercial can.
Plain vegetables — green beans, corn, peas, carrots, beets (without vinegar), mixed vegetables.
Plain pumpkin or winter squash — cubes only — never puree. Puree is too dense for safe heat penetration; Bernardin specifies cube-pack as the only safe form.

Not on this list and not in a Bernardin or Health Canada pressure recipe? Default to freezing instead. A chest freezer holds a season of low-acid prep at zero food-safety risk.

The pressure-canning process at a high level

Read the tested recipe in full. Verify jar size, headspace, and processing time. Pressure canning has zero room for improvisation.
Prep food and pack jars. Hot-pack is standard for most low-acid foods. Follow the recipe's headspace exactly.
Apply fresh SNAP lids and bands fingertip-tight.
Add 5–7 cm of water to the canner (per the canner's manual — not enough to cover the jars; you want steam, not a water bath).
Vent the canner. Lock the lid, heat on high. Let steam exhaust through the open vent for a full 10 minutes — this purges air, which would otherwise lower the internal temperature and make the process unsafe. Do not skip this step.
Apply the regulator (the weight or the dial gauge cover). The canner will pressurize.
Reach and hold pressure. Once the gauge reads the recipe's required pressure (typically 10 lb or 15 lb depending on altitude — see below), start the timer. Adjust heat to maintain pressure; if it drops, you must restart the timer once it returns.
Process for the full recipe time. Do not lower the pressure to "save time."
Cool naturally. Turn off heat, leave the canner closed and the regulator in place until the pressure returns to zero on its own. Never force-cool a pressure canner — sudden depressurization breaks seals and can crack jars violently.
Remove jars, cool 12–24 hours, check seals.

Altitude: change the pressure, not the time

For water-bath canning, altitude adds minutes. For pressure canning, altitude raises the pressure.

The Bernardin and Health Canada rule is:

Dial-gauge canners: a defined PSI step per altitude band. Below 305 m typically 11 lb; above, increases per band.
Weighted-gauge canners: two settings (typically 10 lb and 15 lb). Below 305 m use the lower setting; above, switch to 15 lb.

The processing time stays the same. Open your Bernardin edition for the exact PSI table — do not use US numbers, because Canadian elevation cut-offs differ. The Canadian altitude-adjustments guide lists every Canadian city and its band.

Shelf life of pressure-canned food

Health Canada and Bernardin recommend consuming home pressure-canned food within one year for best quality. Sealed and stored properly, it remains safe longer, but colour, texture, and flavour all degrade past 12 months — and pressure-canned meat is especially prone to texture loss after the second year.

Storage rules:

Cool, dark, dry — pantry or basement shelf. Not above the stove, not in a freezing unheated garage.
Remove the bands after the seal sets. Bands trap moisture against the lid edge and can mask a failed seal.
Label every jar with the date and contents. By February you will not remember which jar of broth is chicken and which is beef.
Inspect before opening. Bulging lid, off smell, mould, discolouration, or a hissing release of pressure all mean discard. The full discard checklist.

See our full shelf-life guide for category-by-category breakdowns.

Common failures

Skipping the vent. The 10-minute steam vent purges air from the canner. If air is left inside, the canner reads "pressure" without reaching the temperature that makes pressure canning safe. This is the most dangerous shortcut in low-acid canning.
Out-of-calibration dial gauge. If your gauge reads 11 lb but the canner is actually at 8 lb, the contents do not reach the temperature that kills botulism spores. Annual check at an extension office.
Pressure drops during processing. The recipe assumes steady pressure. If it drops below the target, the timer restarts. Don't be tempted to "make up the time" by adding to the back end — restart fully when pressure returns.
Force-cooling. Cracking the lid or running cold water on the canner to speed cooling is dangerous and ruins seals.
Adding thickeners. Flour, cornstarch, pasta, rice, or dairy in a pressure recipe block heat penetration. Thicken in the pot when you reheat — never in the jar.
Using untested recipes. Mixed recipes (chili, spaghetti sauce with meat, soup with thickener) require a Bernardin-tested formulation, not a Pinterest one. The pH rule, explained.

First-time pressure canner FAQ

Is a pressure canner loud? Yes. A weighted-gauge canner jiggles audibly — that's its way of telling you the pressure is right. A dial-gauge canner is quieter but still hisses steam. Plan for a kitchen that sounds like a small steam engine for 60–90 minutes.

Can I run a smaller batch than the canner holds? Yes. Maintain the minimum water level the manual specifies (typically 5–7 cm); you can process as few as two jars in a 23-quart canner as long as they're upright on the rack.

Can I leave the canner unattended? No. You need to be in the kitchen the entire processing time to adjust heat if pressure drops or climbs. Pressure canning is not a set-and-forget appliance.

Why does the recipe specify 1 L jars only? Heat penetration depends on jar dimensions. A jar size not listed in the recipe has not been tested at that time and pressure — using a different size is improvising on safety.

What if I lose pressure for 30 seconds during processing? Re-establish pressure and restart the timer from zero. Adding "the missing 30 seconds" to the end does not work — heat penetration depends on continuous time at temperature.

Can I pressure can in glass-top stoves? Check both the canner manufacturer and the stove manufacturer. Some glass-top stoves restrict the weight or footprint a burner can support; some pressure canners have flat enough bottoms to qualify, others don't. Manufacturers publish lists.

When to use pressure canning vs alternatives

Pressure-can when you want shelf-stable low-acid food: green beans, corn, plain meat, broth, dried beans, vegetable soup (no thickener), Bernardin's pressure-tested meat sauces.
Freeze when you have low-acid food and don't want to invest in a pressure canner. Freezing is the safer, lower-equipment alternative for most home cooks. A chest freezer holds a season of bean and meat preparation easily.
Acidify and water-bath only when a tested Bernardin recipe specifies the exact acidification (lemon juice, vinegar, citric acid) and processing time. Pickles, salsa, pizza sauce, and acidified tomatoes fit here. See the water-bath canning pillar.

Every guide in this method

Sources

Bernardin — Home Canning Guide (pressure canning chapter)
Health Canada — Home food preservation
Health Canada — Botulism