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owly 09-10-2021 18:52

Retort bag canning (pressure)
I posted on another (wrong) section about the LEM MaxVac chamber sealer I purchased from Costco on sale at about half LEM catalog price. My intent was to use it for many things including retort pouches, which are what the military uses for MREs. These are designed to be pressure canned... just like a jar or can, but they pack much better, and aren't fragile.

Needless to say, when I got my retort pouches, I was eager to give it a go. I decided to make a batch of chili and can it. The first try was a disaster......... I put it in the chamber with the chili still hot, and of course the vacuum boiled it and spewed it out of the bag, and I had a mess to clean up.
Second trial was today, with everything chilled...... It looked good. I put two seals on each bag, and put a hunk of chuck roast in another bag, and put the entire thing in the pressure canner for 70 minutes per the instructions for jars.
Failure rate of about 50% of the seals.

I then set out to find a solution, and when I get a "bone in my teeth", I don't let go easily. Using a new bag with nothing in it, I sealed it... leaving a fair amount above the seal...... I could easily pull it open. Obviously 2 weak seals isn't much better than one, so I tried repeating the seal in the same location. All my seals were set for max temp and max time. The LEM has 3 presets you configure yourself.... unless you want to use factory defaults, and they are easy to change from the panel. You have to apply vacuum to do a seal, so I have one preset set up for 15 seconds vacuum, followed by max seal temp and time...... Vacuum applies the seal bar.

It seemed that no matter what I did my seals on the retort pouches would fail....repeat sealing in the same location damaged the bag itself.........

Finally the light lit up..... I had an Aha moment. There is adhesive on both inner faces of the bag...... actually the inner faces are adhesive, but the seal was pulling away from one face. The seal bar is heating only from one side. That meant that the other face was not seeing enough heat to "weld" the two together. The solution was to immediately flip the bag after the first seal and run another seal as quickly as possible from the other side.

...............Bingo. The bag welded beautifully, and I was unable to tear it open. It's an inconvenient work around, but looks like it will solve the problem. I unfortunately do not have enough of anything right now to want to run another pressure canning project, and the chili will be just mush if I run it through again.

An expensive machine for a vacuum sealer, chamber vacuum sealers are not for everybody. This one was $600..... on sale from about $1100. They do a superior job on everything, and will seal liquids without sucking it out of the bag as the food saver type do.... Juicy meats, or anything with high liquid content works just as well as drier foods. You can also seal jars of dry goods... set them or lay them in the unit and run a vacuum with the seal bar shut off. It also will vacuum seal foods in virtually any kind of plastic bag that will fit in it, as it doesn't require the expensive textured bags. In the short time I've had it, I've tried it on a lot of stuff, even using zip lock bags, though the factory "welds" on those are poor.

I use sous vide a LOT, and have for quite a few years now, so a vacuum sealer is important to me. I also buy meat in quantity if it's on sale, and it will keep virtually indefinitely in the freezer if vacuum sealed. I've fought with the food saver type sealers for years and they can be a headache. This is a huge rugged machine with a REAL vacuum pump just like my refrigeration vacuum pump, and serious industrial internals with contactors, and other industrial grade parts making up a 65 lb machine.


JBP 10-10-2021 08:40

Re: Retort bag canning (pressure)
Nice info. I'm thinking of trying to can some single serving size portions. My understanding of traditional canning was that vacuum only served to keep the lid tight. It is the pasteurization/sterilization temperature that allowed for long storage time. Do the bags work differently?

owly 10-10-2021 12:11

Re: Retort bag canning (pressure)

Originally Posted by JBP (Post 3499509)
Nice info. I'm thinking of trying to can some single serving size portions. My understanding of traditional canning was that vacuum only served to keep the lid tight. It is the pasteurization/sterilization temperature that allowed for long storage time. Do the bags work differently?

The vacuum also serves to remove air so the product doesn't oxidize / go rancid. The chamber sealer draws down to almost 90 kpa or about 25 HG, which is about as close as you can get to absolute at this altitude leaving virtually no oxygen. Pressure canning does not create a very strong vacuum, and leaves significant head space in the jar. If you plan on long term storage of canned items, flushing the jar with CO2 or nitrogen or argon before sealing it would significantly enhance it's life span. This can be done with an ordinary inexpensive CO2 bottle for a paint ball gun, and a regulator or just a twist knob that opens the valve on the bottle. I use these bottles for carbonation. At about $25 for the bottle and around $4 to fill it, it's small, cheap and light. I also have two much larger Co2 bottles I use for welding, and a bottle of nitrogen for pressure testing refrigeration systems. At $16, this adapter on Amzn seems to be about the best value. It has 1/8" NPT outlet, so you can simply screw in a hose barb, and attach to a small piece of plastic hose. Insert this into your jar or bag, and give it a brief blast to flush out the oxygen, then screw the lid on.

BillKny 10-10-2021 12:23

Re: Retort bag canning (pressure)
I would be REALLY REALLY careful...

If you do not know exactly what you are doing, you are setting yourself up to make some really dangerous food. Like kill-you-dead dangerous.

There is a bunch of just plain WRONG stuff written in other answers to your post.

Removing air is only part of the answer to preserving food. Removing oxygen from the food makes the environment PERFECT for growing Clostridium sp. --bacteria who ONLY grow in oxygen free environments. If you don't know, these are the bacteria that make the botulism toxin. Food contaminated by this critters tastes and smells normal, yet is deadly to eat.

This is not a place to be making stuff up by trial and error. An error could kill you.

How will you KNOW, for 100% sure and certain, that you will have fully and completely sterilized the food?

toddster8 10-10-2021 12:49

Re: Retort bag canning (pressure)
In addition to the points above, while the heat-sealer may seal ordinary polyethylene bags, they are gas permeable. They will equalize with the atmosphere in about a day. I spend many years using this fact to sample soil and aquifer gases. The expensive bags made of special films are needed if one wishes to maintain anaerobiosis. (Of course, unless thoroughly boiled, there is already plenty of oxygen in the food to begin with.)

AJ_n_Audrey 11-10-2021 11:01

Re: Retort bag canning (pressure)
BillKny said it right. At the Master Gardener class in Maryville, TN they start the session on canning by showing pictures of the funeral of an entire family who died from eating improperly canned food. My grandmother used to can, because she lived in Alaska and the growing season is so short it is a necessity. You really need to be careful. The reason canning jars are boiled for so long is to kill any bacteria in the jars and make them safe to be stored. A bad seal can kill you. Not sterilizing the contents can also kill you.

Jdege 11-10-2021 11:29

Re: Retort bag canning (pressure)
I've been using a Sinbo vacuum sealer for many years, to do sous vide.

Nozzle vacuum sealers insert a noozle into the bag, and so will work with non-channeled bags, without the bulk of a chamber sealer.

Unfortunately, it's been discontinued. Every other nozzle vacuum sealer I've seen costs thousands and requires a separate air compressor.

owly 11-10-2021 12:01

Re: Retort bag canning (pressure)
It is good advice to tell people to know exactly what they are doing, but trying to make people fearful is pointless. Instead of fearmongering, point folks to the appropriate references.

Do not just try to scare people with reefer madness type stories...... give them the information / sources they need or don't bother posting!!

The USDA publishes a free downloadable 200 page book outlining the guidelines which can be downloaded here:

The same information is available in countless other places, books, etc, A print version is available for $19 here:

I've been doing home food preservation for over 40 years. It's a family tradition that goes back generations. I do waterbath canning where appropriate, dehydration, vacuum sealing jars of dry products like grains, beans, etc, and vacuum packing various items for freezing. One caution seldom mentioned is that botulism which is an anaerobic bacteria and is the greatest threat to canners. It requires a PH higher than 4.6 to do it's dirty deed (low acidity)... and moisture & lack of oxygen. It can grow in vacuum sealed high PH (low acidity) foods even at refrigerated temps, so these items should be frozen never be stored long in the refrigerator. That kind of information is published in the above book, as well as publications by the likes of Ball, Kerr, National, Presto, and others who sell canning products.

It is utterly silly to imply that flushing a jar with Co2 or Argon before pressure or water bath canning is somehow dangerous!! It WILL extend the shelf life of the product. I know that from actual experience. It is simply one more tool the home canner can use... Nobody even remotely suggested that it replaces pressure canning or water bath.

pesarsten 11-10-2021 12:28

Re: Retort bag canning (pressure)
While home canning certainly deserves proper processing the process for SAFE canning is neither complex or hard to understand.
The USDA publishes easy to understand instructions.
I started canning 15 years ago and love the results.
One additional precaution, not all bad food preservation happens at home. You are at risk from improperly preserved foods from commercial sources if the manufacturer has a hiccup!
I advise anyone who is eating my tasty canned goods to bring to a simmer for 5 minutes as an additional precaution. Proper heating destroys botulism toxin and helps to reduce the risk of illness. I thoroughly heat all commercially produced canned food if it can be heated.

ikanode 11-10-2021 13:55

Re: Retort bag canning (pressure)
Using retort pouches isn't home canning! It's not fear mongering to tell people they can kill themselves and their family by experimenting with canning processes.

The military spent millions of dollars and years developing retort pouches and a canning system to support it. It's unlikely it's possible to do this at home.

owly 05-12-2021 10:24

Re: Retort bag canning (pressure)

Originally Posted by ikanode (Post 3500352)
Using retort pouches isn't home canning! It's not fear mongering to tell people they can kill themselves and their family by experimenting with canning processes.

The military spent millions of dollars and years developing retort pouches and a canning system to support it. It's unlikely it's possible to do this at home.

Unbelievable!! Using retort pouches very much IS home canning using modern technology! It is an available technology consumers can buy. ALL THE SAME SAFETY RULES APPLY to retort canning as to ordinary pressure canning.

It very much IS fear mongering! We do lots of things where we can kill ourselves.... including sailing, but take the proper precautions. People kill themselves by NOT following the rules. You and I have both eaten many canned goods..... commercially canned. The commercial process is the same........Bring the can and it's contents up to the temp necessary to kill bacterial spores from things like botulism. This is exactly what home canners have been doing since long before you were born. That temperature is 250F, which can easily be done in a pressure canner. I know many people with shelves and shelves full of pressure canned low acid foods that are subject to the growth of botulinum if improperly canned.

Claiming that retort canning is different from home canning is utter fearmongering BS. Quit blowing smoke up people's backsides. At least provide USEFUL information such as canning pressure & time charts instead of acting like a silly old woman!! Stating that it is "unlikely that it is possible to do it at home" is ignorant nonsense!!

Here is a good article about retort pouches...... and I can credit you with at least one statement that is not complete BS. The US Army DID develop the technique in partnership with Reynolds Aluminum and another company.

Retort Pouches

ikanode 05-12-2021 11:04

Re: Retort bag canning (pressure)
Here are two contrary views

University of Georgia Home Canning

The fad... Home Canning in Flexible Pouches
Many commercial shelf-stable foods are packed in shiny, flexible “retort” pouches— think tuna fish and juice pouches. Now several websites are suggesting that home food preservers can use these pouches for long-term food storage just by swapping the pouches for mason jars and using existing canning recipes and methods.

Home canning recipes developed for glass jars cannot be used with other shapes and types of containers. Improperly canned food is susceptible to the dangerous pathogen Clostridium Botulinum. The medical consequences of its toxicity are life-threatening.

Skip this one entirely!! Tested recipes for home canning—followed carefully and to the letter—are the only way to ensure a safe final product.
by: FlexibleCreative

I have worked as a canning professional for decades, and have conducted many experiments with pouches.

" ...there is just not a lot of information regarding this method. "
The reason is that while canning in jars is well proven at home, use of pouches is not. Even in industry, it is difficult to control the parameters needed to maintain pouch thickness, seal integrity and preventing of post-process contamination.

Processing in pouches can be dangerous and life-threatening due to botulism poisoning if done improperly, and I don't recommend it for the following reasons:

There may be no space between pouches in the canner. This can lead to under-processing of stacked pouches, because the heat may not reach the center of stacked pouches. When jars are processed, there is room between them for the steam (the heating medium) to circulate.

When pouches expand, they increase the thickness, and the time it takes for heat to reach the center of the pouch. In commercial canning, methods are used to prevent pouch expansion. Expansion, and the reduction of heat to the center of the pouch can lead to under-processing.

When pouches expand, the seal may become strained, and allow entry of bacteria after processing and in storage.

Tests are conducted in factories when pouches are produced, to test the seal strength. This cannot be done at home by most home canners.

The seal strength depends on seal temperature, applied pressure and dwell time. If these cannot be controlled at home, then the seal may be questionable.
Normally, seal examinations are conducted pre- and post-processing. With jars, the post-process test is easy: the button is up or no vacuum is present if the jar is improperly processed. It is much, much more difficult to determine this in a pouch.

I do not recommend the practice of home canning with pouches. To process pouches, following non-official websites, like the one cited in this thread can be dangerous. Only can in jars, and follow prescribed sites such as from or Ball canning books or USDA published processes for jars.

Risking your life is not worth doing otherwise.

Edit: To process refrigerated or frozen components is especially dangerous. During the canning process, the heat from the steam may not penetrate to the center, allowing spores of C. botulinum or spoilage organisms to survive. This can lead to food safety and spoilage issues.

In addition, puffy pouches may indicate spoilage from gas production from surviving microorganisms.

Manateeman 05-12-2021 12:41

Re: Retort bag canning (pressure)
Somewhere around 1977, my wife and I owned a research / pilot plant in Massachusetts where we did work in both aseptic packaging and retort pouch.
Retort pouch technology is NOT home canning.
We packaged seafood for the Army Natick Laboratory which developed the MRE.
We used SwissVac machines and Cryovac Corporation conducted extensive tests at our facility with their machines. The microbiology was done at Cornell University and Cryovac Labs.
If you want to vacuum pack or gas flush pack foods and freeze them and carefully defrost them...fine...just learn what precautions to take. It’s food.
If you wish to learn retort pouch technology we suggest you travel to Germany after taking a few courses in Food Science and Microbiology.
The microbiology costs for laboratory size runs will exceed $ 100,000 per item tested in any technology. The equipment costs will exceed a half million. For example, Ocean Spray built a pilot plant for aseptic packaging which costs millions to run cranberry juice in an aseptic box.
Thus you need two things.
A proper education and a huge budget.
Food Technology is a Science ...not a game ...because there are multiple microbes which can leave you extremely sick or dead. Improper food handling can kill you without any packaging. Any packaging changes the microbiology. NOT use any vacuum, gas flush or pouch technology without a professional education in the subject. It’s complex. It can be deadly.
You asked for a professional opinion. You have it.
Ask anyone who is a microbiologist in food science and they will tell you the same facts. This is nothing to fool with...period.

JBP 06-12-2021 07:26

Re: Retort bag canning (pressure)
I've been looking for a cheap used pressure canner at second hand shops, but haven't been able to find any good ones (16 qts ish). On Ebay they seem a little steep for my experimental foray into canning, especially with shipping. Do you have any suggestions on where to find one?

owly 06-12-2021 08:39

Re: Retort bag canning (pressure)
"post process contamination"..... really??? In a properly sealed pouch I wonder how this is possible.

Expansion is a nonsense concern.... at least with pressure canning. The pressure canner holds pressure on the pouch which prevents it from expanding. Heated liquids expand into steam, and create pressure inside the pouch........ however the water in the canner creates the same amount of pressure, and that will prevent expansion.
***** The only time this would be a concern is with water bath canning ****

(without pressure)

Lack of space between the pouches is hardly something to be concerned about unless you are packing them into the canner very tightly... which is foolish. But this is a potential concern. **** If pouch expansion were real... which it is not in a pressure canner while under pressure, this would be a concern. *****

Rule 1: Don't cram the pouches into the canner. I find that about 5 of the 8 oz rated pouches is as many as I want to run at one time. I also run most things for about 90 minutes at the recommended pressure.

Rule 2: Don't put more than 8 ounces in an 8 ounce rated pouch. The reason is simple. EXPANSION OCCURS DURING THE COOL DOWN PERIOD.... and the seams can burst. The pouch needs expansion space.

The suggestion that this is a "fad" is absurd. There are a small number of people doing it. It requires expensive equipment.... My vac sealer is marginally adequate, and is a unit that lists for $1k+ It does produce a seal, which I then back up with a stand alone heat sealer that will apply a good strong seal that is quite wide.... another couple hundred dollars..... Temp and dwell time as they say is critical to getting a good seal... That is indisputable. It took some experimentation to get a seal that was suitable. Some chamber sealers have an optional seal bar that is easily capable of doing this. I have to remove the item and flip it immediately, and repeat the seal process over the original seal to get a seal I trust.

This statement is patently absurd in the context of retort pouches:

Home canning recipes developed for glass jars cannot be used with other shapes and types of containers. Improperly canned food is susceptible to the dangerous pathogen Clostridium Botulinum. The medical consequences of its toxicity are life-threatening.

This is not a casual endeavor. It takes some commitment in time and equipment. Some trial and error, however the errors are easily observable. It's not something every Tom, Dick, and Harry should be encouraged to try. The results are rewarding when it works. I've taken it to the level of using compressed air at 15 psi AFTER REMOVING THE HEAT FROM THE CANNER... to prevent the pouches from expanding. They can and do expand during the cooling process because the pressure in the canner drops off faster than the pressure in the pouches. This is when seals fail. The pouches are hot, and the adhesive is thermal, and the pressure is increasing.

** This is clearly NOT for everybody. There are many things that are not for everybody

***** A not about botulinum toxin:

The toxin is heat-labile though and can be destroyed at > 185°F after five minutes or longer, or at > 176°F for 10 minutes or longer.

I've been preserving foods doing canning and fermentation processes for over 50 years. I've done many things that are not mainstream, but I have a background in microbiology and chemistry among other things. Careless people get into trouble from carelessness and ignorance...... They always will. I've even cultivated botulism and other dangerous bacteria intentionally just to familiarize myself with them. These are not things most people do obviously. In sailing, I am far more concerned about ciguaterra which cannot be broken down or denatured by any known method, than botulism, which is both easily avoidable and can be broken down at a fairly low temperature. (185F for 5 min).

Manateeman 06-12-2021 14:53

Re: Retort bag canning (pressure)
WOW just WOW. This is a forum for sailors. Suggesting retort pouch technology is feasible on board is ludicrous.
The original poster asked for professionally qualified responses and was give exactly that yet the thread continues.
When are the moderators going to step in and stop this dangerous nonsense.
Retort pouch technology requires understanding food science, microbiology and packaging. We knew all the major innovators in retort pouch. The Army Natick Labs, SwissVac, Ocean Spray Cranberries, Cornell University and the Food Science Department at MIT.
Aseptic packaging and retort pouch technology took years to develop and millions of dollars in funds were spent. The research effort was immense because the risk of illness and death was ever present.
Any suggestion this is is something you can read a few books on or learn at home is comical. You not only need the substantial and broad education but the time and funds necessary to learn these unique technologies ... both the practical and scientific basis. Failures can kill you. This is why facilities which package foods in retort pouch or aseptic drink box or any aseptic packaging...these corporations have packaging engineers, microbiologist and food scientists on staff who continually monitor everything. More importantly...they are FDA inspected.
We find this thread outright dangerous in its oversimplification.
Do not fool with retort pouches, vacuum packaging or anything similar to it.
It can make you extremely sick or kill you.
Captain Mark and crew.

Pete7 06-12-2021 15:09

Re: Retort bag canning (pressure)

Originally Posted by Manateeman (Post 3533144)
When are the moderators going to step in and stop this dangerous nonsense.

The moderator post for canning expertise is currently vacant :whistling:

The discussion has highlighted several different views, all cordial.

The reader now has the evidence they need to take a decision on who to believe and what approach to take. As adults you are responsible for your actions and the choices you make.


JBP 07-12-2021 06:50

Re: Retort bag canning (pressure)

Originally Posted by Manateeman (Post 3533144)
When are the moderators going to step in and stop this dangerous nonsense.

I, for one, appreciate the info from Owly. I also appreciate people who (rationally) post the potential problems and dangers with retort pouches.
Owly sounds like he is reasonably cautious, and his experiments only endanger himself. It's not like he is trying to kill his friends, family, and neighbors by spouting anti-xxx rhetoric. Sure, maybe the problems of home canning with retort pouches has not been worked out as well as with glass, but the only way they will be solved is by people like Owly trying to figure things out.

s/v Jedi 07-12-2021 07:35

Re: Retort bag canning (pressure)
Why not use Mason jars? With a little research and practice you get a reusable option that is completely safe. Much cheaper as well.

We do use a vacuum chamber machine too for dry storage items as well as items that go in the freezer. A chamber vacuum machine allows powdery as well as liquid items to be vacuum packed which isn’t possible with the “Food Saver” class machines.

Last trip we took more than 500 food filled jars with us, bringing back about 75 food filled and 425 empty washed jars which are now ready for next time :thumb:

rfe3 07-01-2022 03:38

Re: Retort bag canning (pressure)
I have done a fair bit of Canning(Metal) and Retort Pouches in the Past and I concur that C. botulinum is a real worry when processing high acid foods and Meats. I have done lots and lots of studing and searching for info over the years and have put together a pretty good library of info that's available on the Internet and through a few Universities. I'll upload a zip file with all the info I have and a few Excel worksheets by U.of Mass to calculate the "F Values" for canning. This stuff is by no means the same as your handy "Ball Canning Guide" this info takes some studing and comprehension of food spoilage.

I have an All-American Presssure Canner for all of my Canning work. A normal Pressure Cooker will NOT have enough pressure to bring the Water Temps to the Critical 121°C that is needed to destroy C. botulinum. I also use a Temp. Probe/Logger like the one in the PDF in every load I do. I sacrifice 1 Can (the coolest one in the middle of the Canner) to take the readings. I open this Can and read the data from the Logger and put it into the Excel spread sheets to check that it's within the proper limits.

Canning Meats and High Acid foods is more difficult and takes more specialized equipment (Pressure Canner, Can Sealer and Temp. Logger) but it can be safely done at home.
I can't seem to find a way to upload this file to this Post as an attachment so I made a link on Google Files. I hope it will work. If it doesn't then PM me and I'll send you an email.

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