Butter, milk and cheese

Sources last opened 2026-08-26.

The short version

There is no research-tested home canning process for butter, milk, cream or cheese. That is the answer, and the shape of it matters: nobody tested dairy and found it dangerous. Nobody ran the thermal process work at all, which is why there is no time and no pressure for anyone to give you [F-9.1] [F-9.2].

The low-acid part is settled. Milk is named in the USDA guide's own list of low-acid foods, and Penn State states that dairy foods are low acid and support the growth of Clostridium botulinum spores at room temperature [F-9.1]. What was never filled in is the process.

NCHFP has looked at the butter directions circulating online and its finding is more interesting than a refusal: what those directions describe is not canning. No heat is applied to the filled jar at all [F-9.2].

Why dairy is the hardest one to argue about

Every other item in this hub has something visible going for the "no". Green beans have a pH you can look up. Pumpkin butter has a measurement attached. Bread in a jar has an Extension service using unusually blunt language.

Dairy has an absence. There is no study to point at, because there is no study. What there is instead is a research centre describing, in careful prose, the specific thing it does not know — and that is a harder thing to link in a comment thread than a scary number.

It is also the strongest position on the page, once you see it for what it is. A source that will tell you what it does not know is a source you can believe when it tells you what it does.

The three live pages, and what each one actually claims

These are named because they are checkable, not to score points. Each was open and unchanged when this page was written, on 26 August 2026. The point is what the pages say, not who wrote them.

A milk procedure with no hold time at all. One page walks the reader through venting a pressure canner and then, at the moment the gauge reaches the target, turning the heat off and letting the canner cool [F-13.2]. That is the whole process. The hold at pressure is zero.

This is worth understanding as a mechanism rather than as a wrong number. A process time is the time the jars spend at the target temperature. The USDA guide states that at 240° to 250°F, destroying bacteria in low-acid canned food takes somewhere between 20 and 100 minutes depending on the food, the pack and the jar size [F-1.3]. Zero is not a short time in that range. It is outside it.

The obvious objection is that the canner stays hot for a long while afterwards, and that is true — cool-down really does contribute heat, and NCHFP says so. It also says there is no way at present to know what percentage of the lethality each canning recommendation gets from cooling [F-14.9]. An unquantified contribution cannot be substituted for a process time. There is nothing here to reconstruct.

The same page is candid with its reader, and that deserves recording: it says most modern research holds that canning milk at home is not safe, and frames it as a personal decision [F-13.2]. A reader who reads to the end is not being deceived. A reader who follows the numbered steps is still following a procedure with no hold time in it.

Water-bath butter with a one-to-two-year claim. Another page gives a boiling water bath time for pint and quart jars and states that the result keeps for one to two years, framed as optional but recommended for maximum shelf life. No source is cited anywhere on the page [F-13.5].

Two things are wrong independently. The food is low-acid, and low-acid food needs 240° to 250°F, which a boiling water canner cannot produce [F-1.2] [F-6.3]. And there is no tested process for butter by any method [F-9.2], so there is no correct number that could be substituted for the one given.

Pressure-canned butter on the boneless meat schedule. A third page applies USDA's boneless meat times to butter and claims about five years of shelf life [F-13.6]. Meat schedules were calculated for meat. Fat behaves differently in a jar and, per NCHFP, can protect spores from heat during processing [F-9.2], which is one of the two reasons NCHFP will not extrapolate a butter process itself.

That page says outright that canning butter is not an approved method [F-13.6]. That is more honesty than several better-ranked pages manage, and it is the difference between a page that is wrong and a page that misleads.

What a reader is actually supposed to do with all this

Notice what none of the three pages could have given you, however carefully written: a validated process. Not one of them cites a thermal process study for dairy, because none exists to cite.

That is the test worth carrying away from this page, and it works on any canning recipe. Not "does this look professional" — all three of these do. Not "does the author sound confident" — all three do. The question is: where did this time and this pressure come from, and can I open the document it came from?

For dairy the honest answer is that it did not come from anywhere. That is not an accusation about anybody's motives. It is the reason the freezer is the answer.

Butter: no tested process

Never tested — which is not the same as tested and found dangerous.

No laboratory has run the thermal process work for this. That is an absence of research, not a finding of danger, and the honest thing to say is that nobody knows. Without the research there is no safe time or pressure to give you, so there is nothing to follow.

No laboratory has run the thermal process work for butter in a jar, so there is no schedule to follow and nothing to adjust for altitude.

NCHFP's answer has three parts and they are worth keeping separate. First, the directions in circulation since 2006 are not a canning process: jars are preheated, melted butter is poured in, lids go on, and the filled jar is never heat processed [F-9.2]. Second, NCHFP names two specific reasons it will not guess at a process — butter is low-acid, and fat can protect spores from heat when the fat is in the product during processing [F-9.2]. Third, it states plainly that it does not know what the microbiological concerns would be for butter stored sealed at room temperature, because no database exists in home food processing that would tell anyone [F-14.11].

Note what none of that says. It does not say butter in a jar has been shown to cause harm. It says the question has not been answered and will not be guessed at.

What to do with the food instead.

Freeze it. Butter freezes for months in its own wrapper inside a bag or a tub, and comes out unchanged. This is the entire answer for a long-term supply and it costs nothing but freezer space.

Refrigerate what you are using. Salted butter keeps for weeks in a fridge.

Clarify it if you want something that sits out. Ghee keeps at room temperature far better than butter because the water and the milk solids have been removed, and it makes no claim that depends on a jar seal. It is a cooking technique rather than a preservation process, and the botulism question does not arise because there is no sealed, moist, low-acid food sitting warm.

Buy it tinned if you want it shelf-stable. Commercially canned butter exists. It is made with process controls, additives and validation that a home kitchen does not have, which is the same reason commercially canned bread exists and home-canned bread does not.

Milk, cream, evaporated milk, cheese and cheese sauces: no tested process

Never tested — which is not the same as tested and found dangerous.

Two separate facts, and pages that get this wrong usually merge them.

The classification is settled and comes from the primary source: milk is on the USDA guide's list of low-acid foods, alongside red meats, seafood, poultry and all fresh vegetables except most tomatoes [F-9.1]. Penn State puts the consequence in one sentence — dairy foods are low acid and support the growth of Clostridium botulinum spores at room temperature [F-9.1].

The process is the part that does not exist. There is no USDA or NCHFP schedule for canning milk, cream or cheese at home, in a boiling water canner or a pressure canner. Any page that offers you one has taken the numbers from somewhere else — usually from a schedule written for a different food — or invented them.

One page in wide circulation lists dairy among the things a pressure canner handles safely, next to low-acid fruits, vegetables and meats [F-13.4]. It is a plausible-looking sentence on a plausible-looking page. It is also the only item in that list with no tested process behind it.

What to do with the food instead.

Freeze milk and cream. Both freeze; both separate a little on thawing and come back together with a shake or a whisk. Cream that has been frozen whips poorly but cooks fine.

Freeze cheese in cooking quantities. Hard cheeses freeze grated with almost no loss for cooking. The texture change matters on a cheeseboard and not in a sauce.

Refrigerate, and buy the shelf-stable versions. Commercially processed UHT milk and tinned evaporated milk are made with validated processes and equipment that home canning does not have access to. Wanting shelf-stable dairy is reasonable; the tested route to it is the shop.

Make yoghurt or cultured buttermilk if what you want is a longer fridge life. Culturing acidifies the milk, which is a different preservation mechanism entirely, and it is a refrigerator food rather than a shelf one.

First: what those directions actually are, in NCHFP's terminology

Most of what we have seen are not really canning, as they do not have Boiling Water or Pressure Canning processes applied to the filled jar. Jars are preheated, the butter is melted down and poured into the jars, and the lids are put on the jars… This is merely storing butter in canning jars, not 'canning'.

National Center for Home Food Preservation, live site, University of Georgia

Opened and read by this site on 2026-08-26.

This is a definitional point and it does most of the work on this page. The methods in circulation do not apply a heat process to the filled jar. They warm the jar, put warm food in it, and close it.

NCHFP's own term for that pattern is open-kettle canning, which it describes as really no canning at all, because the jar with the product in it is never heat processed before storage [F-9.2]. The lid will very often pull down and hold. That is a vacuum forming as the contents cool, and it is not evidence that anything inside reached a temperature.

Note what this quote does not claim. It makes no assertion about how risky the resulting jar is. It is a statement about what the procedure is and is not, and the risk question comes next.

Second: the risk question, answered honestly

Although mostly fat, butter is a low-acid food… It is not clear what the botulism risk is from such a high-fat product, but to store a low-acid moist food in a sealed jar at room temperature requires processing to destroy spores. A normal salted butter has about 16-17% water… We have no kind of database in the home canning/food processing arena to know what the microbiological concerns would be in a butter stored at room temperature in a sealed jar. In the absence of that, given that it is low-acid and that fats can protect spores from heat if they are in the product during a canning process, we cannot recommend storing butter produced by these methods under vacuum sealed conditions at room temperature.

National Center for Home Food Preservation, live site, University of Georgia

Opened and read by this site on 2026-08-26.

Read the second sentence twice. "It is not clear what the botulism risk is from such a high-fat product." That is a research centre telling you it does not know, on a page where it would have been easier to write something firmer.

Then it gives you the reasoning it does have. Butter is low-acid. Salted butter carries roughly a sixth of its weight as water [F-9.2], so it is a moist food rather than a dry one. Storing a moist low-acid food sealed at room temperature requires a process that destroys spores. No such process has been developed for butter. And fat is not neutral in this — it can shield spores from heat during processing, so a schedule borrowed from a leaner food would not transfer even if somebody tried.

The conclusion is the same page's last word on it: with no testing having been conducted to validate these methods, NCHFP would not recommend or endorse them as a safe home-canning process [F-9.2].

That is what a Category B "no" looks like when it is written carefully. Nobody claims a finding they do not have.

Third: dairy's classification, which is not in doubt at all

Dairy foods are low acid and support the growth of Clostridium botulinum spores at room temperature.

Penn State Extension, foods that are not safe to can, live

Opened and read by this site on 2026-08-26.

Penn State Extension, last updated 30 August 2023. One sentence, and it settles the half of the question that is settled.

This is a classification, and it matches the primary source: the USDA guide's list of low-acid foods names milk explicitly [F-9.1]. Low-acid means a pH above 4.6, and it means a boiling water canner is the wrong tool no matter how long you run it.

What this sentence does not do is supply a pressure process. Knowing a food is low-acid tells you which category of process it would need. It does not tell you the time, and for dairy nobody has calculated one.

What people ask next

People have been canning butter for generations. Does that count for nothing?

It counts for something, and it is worth being precise about what. NCHFP dates the specific directions now circulating to around 2006 [F-9.2], so the "generations" framing is doing more work than the history supports for this particular method.

More importantly, a track record of jars that did not make anyone ill is weak evidence about a hazard that is rare, sporadic and depends on whether a spore happened to be present and whether the jar happened to sit warm. Absence of harm across a small number of jars is consistent with both a safe method and a risky one. That is precisely why thermal process development exists and why it is done in a laboratory rather than a kitchen.

None of which means the people doing it are careless. It means the question is not one that personal experience can settle in either direction.

What about the pages that give a pressure canning time for butter?

One such page borrows the USDA schedule for boneless meat and applies it to butter [F-13.6]. The numbers are real numbers; they were calculated for a different food with different density, different fat behaviour and a different heat penetration profile.

That page is also, to its credit, open about the fact that the method is not approved and that everyone does it differently [F-13.6]. That is a meaningful difference from a page that presents an invented schedule as though it were tested, and it is worth saying so.

Its cooling instruction is a separate problem. It tells the reader to shake the jars at intervals as they cool, to mix the fat back in [F-13.6]. The guide's instruction is to let jars sit undisturbed while they cool [F-11.2], because the seal is forming during that period.

Is 'canned' cheese in the shops the same thing?

No, and the difference is the whole point. Commercially canned dairy is produced with validated thermal processes, continuous monitoring, and in some cases formulation changes that are not available to a home canner. A commercial process is designed by process authorities for one specific product in one specific container.

The existence of a shelf-stable commercial product is never evidence that a home version is possible. NCHFP makes the same point about bread and cake in jars: commercial versions use additives, preservatives and processing controls not available for home recipes [F-9.5].

Can I water-bath butter if I just want it to last a year?

There is a live page offering exactly that, with a claimed shelf life of one to two years and no source cited anywhere on it [F-13.5]. The mechanism problem is straightforward: a boiling water canner works at the temperature of boiling water, which is 212°F at sea level [F-6.3], and low-acid food is sterilised at 240° to 250°F, temperatures reached with a pressure canner operated at 10 to 15 PSIG [F-1.2].

So the method is the wrong category of process for the food, before you even get to the absence of a tested schedule. Freezing gives you the year you wanted, with better butter at the end of it.

I have jars of home-canned butter or milk in the cupboard already. What now?

Do not taste them to find out. Tasting is the one check that cannot be undone, and the organism at issue does not reliably announce itself by smell or appearance.

A held seal is not the reassurance it looks like. Forming a vacuum is listed last among the things canning does, and it is a consequence of the process rather than the mechanism that makes food safe [F-1.9]. Jars closed by the open-kettle pattern seal routinely.

If you want the reasoning laid out in full, the mechanism page in this hub covers what each unsafe method does and does not accomplish: open kettle, oven, inversion, dishwasher, sun.

What this page rests on, and when it was last checked

National Center for Home Food Preservation

live site, University of Georgia · checked 2026-08-26

Maintains the USDA guide but is not identical to it. Where they differ, this site shows both and says so.

Penn State Extension, foods that are not safe to can

live · checked 2026-08-26

USDA Complete Guide to Home Canning

2015 revision · checked 2026-08-26

Still the current revision. It is a fixed 2015 document and the live NCHFP site has moved past it on at least three separate subjects, so the two are cited separately here and never treated as one text. (On one of those subjects the two texts differ in at least five specific places within a single panel. The counts measure different things and both are stated precisely on the pages that use them.)

Read these yourself

NCHFP — canning FAQs, including the butter answer quoted above
nchfp.uga.edu

Penn State Extension — Foods That Are Not Safe to Can
extension.psu.edu

USDA Complete Guide to Home Canning, 2015 revision
nchfp.uga.edu

NCHFP — Equipment and Methods Not Recommended
nchfp.uga.edu