I'm sure other forum members have insights on the food safety issues. I would guess that testing has simply not been done to determine safe times. Milk is low pH and there would also be issues with the fat in the milk, which affects heat-penetration.

But I'd approach it from another angle. Adding dairy to canned soups, assuming you could do it 1) takes up more space (more bulk=more jars=more processing time and increased storage needs) 2) in all likelihood would result in compromised flavor due to the high temperatures. I don't like commercially canned milk or ultra-pasteurized products and doubt it'd be any more appealing in a home-canned product.

You can certainly process vegetarian soups and it's very simple to add fresh milk when heating, so to me personally the greatest benefit lies in not adding it when canning.

The UGA National Center for Home Food Preservation provides basic information on canning of soups that you might find helpful. Then, if you have a specific recipe in mind but aren't sure about times, procedures, etc. just ask away. There are lots of people here glad to help.

Carol

Here is a link that might be useful: Canning Soups

I want to can some corn and crab chowder using low fat (2%) milk, no butter. How long should I process at 10 lbs. pressure?

I'm sorry. No safe processing times have been developed for soups containing dairy.

Dairy products contain fat which insulate botulism spores from heat.

Canning with dairy is a dangerous practice.

Carol

I agree with Carol. Using dairy products in canned soup recipes is dangerous. More importantly as Carol also said, it is easy enough to add those products to the canned base at preparation time (just as you would to a can of Campbell's ;).

The reason: The fats in oil and dairy products encapsulates any bacteria in the product including botulism and this encapsulation prevents the heat used in the canning process from killing the bacteria.

The soup canning link Carol provided above provides precise instructions for those soups that are safe to can with this proviso:

Caution: Do not add noodles or other pasta, rice, flour, cream, milk or other thickening agents to home canned soups. If dried beans or peas are used, they must be fully re-hydrated first.

Be safe in your canning.

Dave

Basically its the protien content of these dairy components. Because they are complex, they can support botulism as well as other dangerous toxins. Fats can also go rancid and affect flavor. Some people can meats and fish, and these are well cooked and done in pressure canners, because these are less complex and are treated with heat at the proper temperatures to kill botulism, they are considered easier safer to home can. The ONLY thickening agents that are allowed in home canning are things like modified food starches, which are a more stable starch copared to flour or regular corn starch. For canning dairy and such, your better off making batches and freezing it.

I can corn chowder omitting the milk and cheese. I add them when I open the jars. My recipe does not include meat or seafood; I use the chowder "base" and add whatever I have leftover; salmon, chicken, crab, halibut, etc.

I pretty much use the chowder to use up small portions of the fish/chicken so nothing goes to waste. I can this in pint jars because by the time I add the milk, cheese and leftovers, I've got almost a full quart jar which is plenty for me and DH.

From Elizabeth Andress:
Canning butter and milk
There are no established safe procedures to recommend for canning these products at home. The various procedures for "canning" butter at home on the Internet on personal sites are not always even canning, and they contain several safety concerns. They also have not been thoroughly challenged in microbiology studies to know you will always get a safe product.
Milk is not a good candidate for canning at home. The amount of heat that would have to be applied to kill harmful bacteria that would grown in this product in a sealed jar at room temperature would be extremely detrimental to quality. Therefore, no one has scientifically developed a canning process for milk to be used at home.
Milk is a finely balanced emulsion of proteins and fats in water. If the proteins are overheated, they drop out of suspension and the milk separates. Industry has special equipment and superheating as well as other methods available that protect quality and chemistry of the product which cannot be duplicated at home.
For further information, here is our notation on canning soups about thickening:
http://www.uga.edu/nchfp/how/can_04/soups.html
Here is a page on insuring safe canned foods:
http://www.uga.edu/nchfp/how/general/ensuring_safe_canned_foods.html
Elizabeth Andress
--------------------------------------
Elizabeth L. Andress, Ph.D.
Project Director, National Center for HFP
Professor and Extension Food Safety Specialist
Department of Foods and Nutrition
The University of Georgia
208 Hoke Smith Annex
Athens, GA 30602-4356
Phone: (706) 542-3773
FAX: (706) 542-1979

I made the expensive mistake of trying to can something with milk. I even went and bought a good pressure canner. After a trip down east, renewing my love for good seafood chowder, I spent a load of money on fresh seafood, and made up a huge stock pot full. It was perfect, almost as good as in the Maritimes.

My plan was then to can the rest, so I could enjoy a treat once a week or so. The milk separated, and the whole thing looks terrible. I haven't just tried eating it, or seeing how it tastes. Maybe I can still salvage it by pouring off the liquid and adding fresh cream when I heat it up.

As for the bacteria, I used the 20 psi weight, and processed the batches for over an hour, so I'm pretty certain most of the bacteria, even botulism, must be dead. While fat may encapsulate the bacteria, at some point everything in the canning jar, food, fat, and bacteria, reach about 260 degrees F, with that 20 psi weight, and I'm pretty sure even this encapsulated bacteria feels the heat, and dies.

I wasn't aware that anyone even made a 20 lb. weight for a pressure canner. 15 lbs. is the maximum weight available.

Salvageable? Possibly. Safe? Possibly not. It's your choice of course but I would toss it due to the risk.

Had you frozen it when made there would be no problem.

Dave

If you offered me 2:1 odds I'd bet money that there's botulism in there. Those spores are tough little bastards.

The problems with botulism are that it's undetectable, it affects people regardless of health status (some studies show a greater risk for healthy people than old/sick), and it's really bad (you could end up fully paralyzed but fully conscious on a ventilator for weeks). It's the only food bug that I think is never worth the risk.

You could try to salvage the soup by boiling it at a full boil for 10 minutes, but even then I'd be worried. An hour is about the regular time for canning soups, and if it's thick you probably weren't getting the most even heat penetration (which occurs mostly by convection in canned products). Plus the canning probably ruined the texture.

I'd continue to think of it as an expensive mistake, throw it away unopened (for the potential gross factor since it's separated), and as a consolation prize I'd treat myself to the ingredients required to make a new batch. And some good beer for the comfort that's in it.

Melissa

I would toss that soup, treat it as though it has botulism. I would suggest using the decontamination process, too. This really could be deadly. My advice, do not even open the jars !
I test pressure canner gauges and never have heard or seen a 20 lb. weight of any sort.
Please, buy yourself a current Ball Blue book and use the recipes in there or any of the USDA/extension books.
You can use the site online for free.

Thanks for all the replies, and the concern.

Yes, I swear, I have a 20 PSI weight that came with my Mirro pressure canner. It came with a 10, a 15, and a 20 PSI weight. I found a boiling point table online and found that 20 PSI above ambient atmospheric pressure results in a boiling point of 260 degrees F, far above the "recommended minimum" for killing bacteria.

Even on its' website, the Mayo Clinic says to can foods at 250 F for 30 minutes to kill botulism, and I exceeded that by over double. The 'Medicine.net' website says "Because botulism neurotoxin is destroyed by high temperatures (85 degrees C for five minutes)," .. again I am way over the deadly point in my canning, but I do appreciate the comment about boiling the stuff one more time before trying it.

As it happens, I am an inspector at Health Canada, though not under the Food & Drugs Bureau. I also have some connections with our CFIA (Canadian Food Inspection Agency). Although their main dealings are with commercially prepared foods sold at grocery stores, I'll see if I can arrange to drop off a couple of jars to them, to get a bacteria count, to satisfy both my own curiosity, and to be able to post some intelligent results here.

Meantime, I will ponder the situation, and, as Melissa so wisely suggested, do so over a cold pint or two. I like the way you think, girl. :)

Steve, remember that every molecule in the soup would have to be at 250°F for 30 minutes to kill the botulism. A thick soup with mediocre convection *might* take longer than 30 minutes to go from its own boiling point (below 212°F since milk boils at 180) up to 250°F. So I don't think you met the requirement. That combined with the no-oil-in-canning prohibition, and the fact that it separated and looks gross...new seafood and the energy to freeze this batch will be cheaper than that ventilator.

Given the time of year, I highly recommend you look for either Buffalo Bill's Orange Blossom Cream Ale or a maibock (malty spring beer). My local brewery (Legend in Richmond VA) has their maibock for about 2 weeks every spring. I had two pints today and have to get back there at least twice in the next week to get my fill till next year. They bottle most of their beers but not this one, and it's my favorite beer ever.

Melissa

I would have that regulator inspected and pressure tested. 20lb weights are unheard of. Something this important should be checked twice. If your regulator is miss-labeled then your 20# will be 15#, 15# 10#, 10# 5#... Very frightening. Be safe and have it checked or just buy a new one. The lives and health of people subject to your canning is just not worth the risk.

I have found two commercially available canned butter products. It is possible to can butter. Does anyone have any ideas how?

Well how in the world is clamchowder processed commercially? It can be done but how?

It seems odd to me that so many people claim that the problem with canning dairy is the fat. There is no evidence that fat is disallowed in recognized safe canning recipes. Organizations like the National Center for Home Food Preservation, who are very highly respected, publish recipes which call for pork fat to be added to ground lean meats prior to canning.
While there is truth in the shielding effect of fats on bacteria (look at the FDA recommended time and temperatures for milk and cream pasteurization) there has been no sited data which correlates the restriction of milk products to fat. If any of this information exists, please post a source for it. I have never heard of proteins shielding bacteria from heat damage, so I would love to see a source for that as well. Otherwise, it seems that milk may be perfectly safe to process in a pressure caner, and the problem is knowledge, not safety.

Great info from everyone, very good thread here. I have a similar chowder that I just pressure canned. I intend to keep in the refridge for only a month or so, so I think it should keep. What are your thoughts????? I know alot of poeple are asking why not just freeze it. But to be honest I love the convenience of a small jar ready to eat, just pull the top & dinners served. Not to mention freezing alters the taste more than canning in my opinion. But would love some expert advice, I'm a newby at this

I have talked to my cousin who has one half of her family being Mormon. She cans "everything" but she does not can milk for botulism reasons. She's also a nurse.

She has been helping me get back into the canning mode after being out for 20 years.

I have found a great corn/potato chowder recipe I was hoping to can. But, now I am afraid to. So, I am going to can everything EXCEPT the milk and add the milk when I open it to heat and eat.

Hope this idea helps.

Well - crikey. Campbell's has various soups that are loaded with fats and dairy. 3rd ingredient below: cream. So clearly there's some way to safely retort process food containing them. Just not at home. When I worked in a lab decades ago we sometimes autoclaved very large volumes of media - maybe up to 1L at times - and it never had a problem w/contamination. I can't remember how much longer the liquid cycle was...maybe about 10 minutes longer. Of course, I'm not saying this applies at home to everyone. I'm just saying you could conceivably do this safely at home, if you really knew what your were doing. The various safety bodies are probably wise to assume most people at home do not.

Here is a link that might be useful: http://www.amazon.com/Campbells-White-Sodium-Mushroom-10-5-Ounce/dp/B0009XQRUK

Irradiation of the foods, added stabilizers, preservatives, and misc. other additives aside, commercial canning equipment can do many things that the average home pressure canner canNOT do.

Dave

My advice would be to create the entire recipe with out the dairy. Can this recipe as is with out the dairy.

When you finally open the canned jar to cook, you then can add the dairy stuff.

The Amish can Milk and it is safe. The Government shut all canning of milk products because it wasn't good for the monopoly on the milk industry. pressure cook the butter w/milk solids for 70 min. just like you would meat. your welcome

I certainly don't espouse such a conspiracy theory. A time old excuse that rebel canners give is that other people have done such and such and they are still alive. That fallacy (I call it the Russian Roulette fallacy) does not address possible dangers. If a procedure has not been tested and found safe, I won't take a chance. There is so much one can safely can, why gamble with your life?