Do I have to boil my home-canned vegetables

Three separate claims are packed in here and they are usually quoted one at a time, which is how this passage gets misread in both directions.

What boiling does. Ten minutes of boiling should destroy the toxin when it is present, with a minute added for each additional 1,000 ft of elevation. The toxin is heat-labile. That is a real and useful property and it is why this instruction exists at all.

What boiling is for. The caution is aimed at low-acid and tomato foods not canned to the recommendations — the jar of uncertain provenance, the batch you now suspect, the method you have since found out was not tested. It applies even when you can see nothing wrong.

What boiling is not. Read the last two sentences slowly, because they are the ones that get cut. This is explicitly not offered as a way to make significantly underprocessed food edible, and it is explicitly not a guarantee that boiling overcomes the hazards of other methods. The guide is offering a defence, and telling you in the same breath that it is not a rescue.

This is the passage that gets summarised as "USDA says you don't have to boil it." What USDA actually says is that you may skip the boil when you are sure of all eight of these, and the eight are not decorative.

Four of them are about the process and they are settled at canning time: it went in a pressure canner, the gauge was accurate, the times and pressures were current and matched to the jar size, pack style and food, and the altitude adjustment was applied. If you cannot personally vouch for all four, you are not in the exemption, and no inspection of the jar can put you back in it.

Four of them are about the jar in front of you now: sealed and concave, nothing leaked, no liquid spurts when you open it, no unnatural odour.

The word doing the work is "sure". This is a checklist for someone who canned the food themselves by a tested schedule and remembers doing it. It is not a checklist for a jar you were given, a jar from a batch you have doubts about, or a jar canned before you knew what an accurate gauge was.

Note also which condition is not in the list: nothing here says a seal proves the food was heated. The seal condition sits alongside four process conditions precisely because it cannot do their job.

Read the last line first, because it is the one that makes the rest matter. NCHFP's live "For Safety's Sake" page says it was extracted from the 2015 guide. Set the two side by side and they differ in at least five places [F-11.4].

It adds a CDC note the printed guide does not contain, dated July 2013, saying CDC's recommendation is to discard any home-canned food that might contain botulism toxin. That note is the bridge to the third text below, and it has been sitting on the page for years.

It defines boiling, which the print guide does not. Large foamy bubbles breaking all over the surface. That sounds trivial and is not: a pan at a lazy simmer, lid on, with a few bubbles at the edge, is not boiling, and the ten minutes is measured on the real thing.

It rewrites three of the eight conditions. Condition one gains "operated according to the procedures in the USDA guidelines". Condition five changes from "firmly sealed and concave" to "firmly sealed and indicates a vacuum seal is present". Condition eight gains "No mold is present."

None of these changes is announced. There is no revision note, no changelog and no date on the edits. A page that quotes "the USDA guide" while copying from this web version is quoting a text that has quietly moved, and will not know it. That is not a scandal. It is just what happens when a fixed document and a living website carry the same title, and it is worth knowing about before you referee an argument between two people who each have one of them open.

That is the whole rule as CDC gives it. A heading that says boil some foods for 10 minutes before eating them, a list of what those foods are, and the altitude adjustment.

There is no eight-condition exemption. There is no "unless you pressure canned it properly". The list says all low-acid home-canned foods, and home-canned tomatoes are named separately at the top of it.

The page was last reviewed in May 2024 and last updated in February 2026, so this is not an old document nobody has looked at [F-11.5]. It is the most recently touched of the three texts on this page.

What CDC does not do is explain the difference from USDA, or cite USDA at all. USDA does not cite CDC either [F-14.7]. Two federal bodies, two live answers, no conversation between them on the page.

Worth its own slab because if you do decide to boil, this is the part that determines whether the ten minutes counted.

Large foamy bubbles, breaking all over the surface, not just at the rim of the pan. In a saucepan, uncovered or partly covered, stirred so the heat reaches the middle of a thick food rather than hammering the bottom.

Start the clock when the whole surface is doing that, not when the pan begins to steam. Ten minutes at a genuine boil is a small job. Ten minutes at a simmer is a different job that you did not mean to do.