Canning safety

Nearly everyone arriving at this hub is asking a version of the same question, and it deserves a direct answer rather than reassurance. The answer is that the danger is real, it is narrow, and it is entirely avoidable by following rules that were established by testing and are published free.

Why this hub cites everything

In a category where getting it wrong can hurt someone, an opinion is worth very little. Every processing time and safety claim on this site traces to the National Center for Home Food Preservation, the USDA Complete Guide to Home Canning, or a named university extension service — and we link the source next to the claim so you can check us rather than trust us.

That is not a formality. Most of what circulates about canning online — thickening a recipe, halving the salt, canning in an oven, sealing jars with hot paraffin, reusing lids, inverting jars to seal them — is either untested or has been tested and rejected. The habit of asking "who tested this, and where can I read it" is the single most useful thing to take away from this hub, and it is exactly what how to find safe canning recipes teaches.

The four things that actually matter

• Acidity decides the method. High-acid food, pH 4.6 or below, can be water bathed. Low-acid food must be pressure canned. See botulism and home canning.
• Altitude changes the numbers. Water boils cooler as you go up, so processing times and pressures change. This is not optional and it is not a rounding error. See altitude adjustment.
• A recipe is a tested process. Substituting ingredients, thickening, or reducing acid invalidates the tested time. Follow it exactly.
• Check the seal, then check it again. A lid that flexes has not sealed. See how to tell if a jar sealed.

What we will not do

We will not tell you a shortcut is probably fine. Where guidance has changed — steam canning is a good example, now sanctioned for high-acid foods under specific conditions after USDA-funded research — we say what the conditions are rather than reporting the headline. And where a popular practice is unsafe, we say so plainly even when it is the thing people are searching for.

That last one has a cost. Some of the highest-volume searches in this category are for methods that are not safe, and the honest page is the one that ranks for the query and then corrects it. We would rather do that than take the traffic on its own terms.

Start with the fear you actually have

If it is botulism, read botulism and home canning. If it is the general question of whether any of this is a good idea, read is home canning safe. If it is a specific jar on your counter right now, how to tell if a jar sealed is the fastest answer.