Sources

Every document this site rests on is listed at the foot of this page, with its own date, the date somebody last opened it, and — where there is one — a note about what makes it awkward.

The list is not typed out here in prose. It is generated from the same registry the rest of the site reads, which is the only version that cannot quietly fall out of step with the pages. If a check date changes in the registry, it changes here and on every page that rests on that document, in the same edit. A hand-written source list on a site that claims to know which text is current would be the first thing to rot.

How to read an entry

Each entry gives you four things.

What the document is. Named in full, not as "the USDA" or "Extension". Those are organisations, and organisations publish more than one text. Several of the longest-running arguments in home canning are two people quoting two different documents from what they think is one source.

The date the document carries. Its revision year, its "last reviewed" stamp, or an honest statement that it carries no date at all. One source here has no printed date anywhere on it, and saying so is more useful than inventing one.

The date this site last opened it. This is the one nobody else publishes. It does not mean the document was published then. It means a person went to that URL on that date and confirmed the words quoted on these pages still read that way, in that place. It is a claim about the site's own diligence, and it is deliberately falsifiable: if a document changed last month and the check date here is older than that, you have caught the site out and should say so.

A note, where the document needs one. Supersession, a live contradiction with another entry, a scope that is narrower than people assume, or a caution about what the document may and may not be cited for.

Three kinds of entry, and they are not equal

They sit in one registry so that every quotation gets a document, a date and a check date. They are not interchangeable.

Research-tested guidance. The USDA Complete Guide to Home Canning, the National Center for Home Food Preservation, and the land-grant Extension services. Processing figures come from here and nowhere else.

Federal health guidance. CDC's botulism material, which is written to a different reader than the canning guidance and updates on its own schedule. Worth knowing that CDC's three botulism pages carry three different review dates; they were briefly held under one key on this site, which put one date stamp on three texts, and were split apart the moment that was noticed. On a site whose claim is that it knows which text is current, that is exactly the mistake it cannot make.

Documents that are not tested guidance at all. Two manufacturers, one independent ad-supported site, and one piece of journalism. Each is here for a specific and limited reason — a free public service, a disclosed provenance for numbers that circulate without one, on-the-record quotes from named food scientists — and each is marked with what it is. No processing figure on this site is ever taken from one of them. A manufacturer validating its own guidance in-house is a real process; it is not the same category of evidence as a published thermal-process study, and the people who maintain the USDA guide will say so on the record.

What this list is not

It is not a reading list of everything consulted. It is the set of documents pages here actually quote or rest on, which is a smaller and more accountable thing.

It is also not a claim that these documents agree with each other. Several of them disagree, in writing, today — that is what the notes are for, and it is the subject of a whole section of this site. See where the guidance stops, or, for the cleanest single case, steam canning: what changed, and when.

If you find one out of date

Say so. A message that reads "this page changed on such-and-such a date and your check date is older than that" is the most useful thing this site can be sent, and it is more valuable than a compliment. Contact has what to include. The standards these dates are held to are set out on how this site works.