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Thread: canning in plastic bags

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    Default canning in plastic bags

    Hi All!

    I am a new member with hopes of having a productive discussion on vacuum seal bags, retort pouches, and the possibility of using such as a substitute for canning rather than using jars or cans.

    I am a senior citizen living in Alaska and I am still gainfully employed as a health care professional. Naturally, my undergraduate discipline was science but once one specializes, focus become intense and very narrow in one's specialty. Still, I have a lust for the daily application of certain areas of science and how I can use technology to my advantage in my daily life.

    I grew up "country" in a rural area of Kentucky. I have changed little in that respect never abandoning my "country ways", good morals, and strong work ethics. We always had a large garden which is another way of saying we always had plenty to do around the farm from Spring to Fall. Grandpa and I would plant and tend the crops (among other things) and Grandma and mom would put up our harvest for future use (among other things). Canning and drying foods were instrumental to our way of life. Leaving the farm in no way means that I tossed aside all that which I learned from living on a small farm. Conversely, this has carried through to today. I still hunt and fish as well as harvest wild edible plants which nature has afforded me. All this brings me to where I am today and my continued interest in preserving foods.

    While living in Southeast Alaska (Prince of Wales Island), hunting, fishing, and gathering various plants became quite important ..... also it was fun. Canning wild game and fish was almost a weekly chore. It was then I began wondering why a person couldn't use vacuum bags as a means of retort (canning using heat). Things change from time to time but not so long ago my surgical instruments were placed in a thick, clear plastic bag, sealed with a heat sealer, and these bags were placed in the autoclave (high heat steam) for stabilization. Infection Control personnel maintained that unless the integrity of the bag was violated, instruments would remain sterile for many, many months. I decided to give "canning in a bag" a go. I had smoked some COHO (cold smoke) and I took a large piece, placed it in a plastic sterilization bag, sucked out the air and heat sealed the bag. I placed the bag in my pressure cooker, brought it up to temperature and held it at that pressure for the prescribed time. When I opened the lid, gases that had not been totally evacuated had caused the bag to inflate but as the contents cooled, the bag "suck back down and around" my fish causing it to *appear* as it was before being placed in the pressure cooker. I threw the bag on the top shelf in the pantry and left it there for more than a year occasionally checking the appearance of the bag for loss of vacuum seal. It didn't appear to have lost it's seal after a year so I opened the bag and gave the fish a "sniff test" and "taste test". The fish was eaten and I'm still alive having never gotten sick.

    Since that time I've tried to obtain scientific data about "canning in a bag" and I've met with failure with each attempt. I have talked with the University of Kentucky Extension Office, Univ of Alaska Extension Service, as will as the Univ of Wisconsin and Tenn. Nothing! All were unaware of any such methods of retort. I even called Ball jar company thinking they could offer the name of an outfit that could provide me information. Nothing!

    Have any of you used vacuum bags in a pressure cooker to preserve food or do you have any *reliable* information on this process? If you have used this process and been successful, would you mind sharing this information?

    Thanks,
    Harold
    Last edited by Harold; 10-28-2009 at 03:40 AM.


  2. #2
    Senior Member Winnie's Avatar
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    It's never even crossed my mind. I'm not sure I'd want to do it though, not for long term storage at home, there are too many variables and possibilty of damage to the bag.

    However, I have seen food preserved this way in a chain of shops over here called Aldi. Their main supply of stock comes from europe(Germany I think) but I don't know the mechanics and theory behing the process. I have to say, it's mainly been potato dishes and the shelf life is well over 6months. If I get to go there soon I'll try and remember to pick one up.
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    Harold - welcome to the forum. I would imagine that the biggest challenge is sterilization and keeping bacteria from being introduced into you "bag". Sounds as though your research is well beyond my knowledge of the topic. Good luck. I usually invite folks to Introduce themselves here http://www.wilderness-survival.net/f...splay.php?f=14 so that they can recieve a proper welcome to the forum.
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    Harold, as I understand it, almost all of the canning information comes from research conducted at either Penn State University or the University of Georgia. The former serves as the research platform for the Extension Service Center for Excellence and the latter as the base for the National Center for Home Food Processing and Preservation.

    I have never heard of using any plastics (bags or otherwise) for home canning and I doubt any research has been conducted on it. You might contact the NCHFPP, in particular Elizabeth L. Andress, PhD. She is the Project Director.

    http://www.uga.edu/nchfp/contact_more_info.html

    The USDA just issued a 2009 version of the Complete Guide to Home Canning based on research conducted at both institutions. This could well be something that could be added in the next issue assuming their research shows it to be viable and safe. I like the idea of getting away from glass containers. The benefits are pretty obvious in any outdoor application.

    Great idea!! Let us know what you find out. This is an interesting avenue to explore. And, as Crash said, an introduction would be welcome.

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    Wouldn't it be called "Bagging"?
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    Good Day to All!

    I was happy to see that I had received replies to my query. Naturally, like most anything, positive and negatives aspects can be brought to light during a discussion. Winnie pointed out that an apparently similar process is used in Europe. Though I am very familiar with Aldi, having lived in Deutschland for many years (my Frau is Deutsch and my daughter still resides in Schweinfurt, DE), I had not noticed packaging of food in vacuum bags. That speaks loudly to my attentiveness doesn't it.

    To the best of my memory, I first noticed unrefrigerated vacuum packed Salmon at the airport in Seattle, WA. Having been smoked and commercially processed in vacuum bags, I gave little thought to this way of storage dismissing any concern for safety because the fish had been first "cured" then vacuumed packed, hence, little need for refrigeration. Later, I thought this might be a good way to go.

    The "up-side" to packaging in this manner is convenience of transporting food in luggage or shipping foods (less weight) without fear of glass breakage during shipment. Another advantage is one could simply place the pouch in boiling water, heat the contents, open and then eat. Nice for camping! One obvious down-side is the ease with which vacuum packaging could be damaged if mishandled. Of course, the same could be said for glass.

    I really have little concern about content sterility over the short haul (perhaps a year if handled properly). If the pouch is brought to temperature, pressure, and prescribed cooking-time then I am confident that life no longer exist within the pouch assuming the pouch is not damaged. The same applies to glass and cans. My concern is, how long will the vacuum seal last provided there is no damage to the bag?

    I had a few extra minutes today and performed a quick search for “retort pouches”. Surprisingly I found quite a few sites some of which specifically addressed retort pouches being capable of withstanding temperatures up to 265F. Apparently, food storage retorting in pouches has been going on for quite some time in other countries but to a much lesser degree in the US. But there does seem to be an emerging up-swing in America.

    I would hope that this thread might serve as an impetus to encourage others to give pouch retorting a go. I certainly plan on experimenting with this further. Perhaps those attempting this process would report their experiences from time to time.

    I have a few ideas that I will soon try. As an example, hospitals include a sealed vial containing live spores in most every autoclave load. Once the cycle is complete, the vial, which passed through sterilization, is incubated as a test to see if any spores survived the autoclaving cycle. If none survive, i.e., no microbes are cultured, then sterility has been achieved. A very similar test can be utilized when canning foods. As a side thought and worthwhile note, at one time a special autoclave tape was placed on the outside of each bag. This tape would change color when a certain temperature was reached. At that time it was believed that one could claim success if the tape changed colors. If was determined that this was not the case! Along with the tape, a test strip of different design was/is placed in each and every bag being autoclaved today. Still, changing of color only indicates that proper temperature was reached but does not mean that instruments are sterile. For something to be sterile, not only must it reach a certain temperature but that temp much be maintained for a specified period of time. Indicator tapes and strips only indicates desired temperature has been reached, hence the need for vials containing live spores that resist high heat and time. The take home message is, if you are using indicating tape or strips then don’t be fooled into believing that the contents of your jars are free of live organisms.

    Harold

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    Senior Member Winnie's Avatar
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    I mean't to ask Harold, the pressure cooker you used, was it a domestic pressure cooker or one of the canning pressure cookers?
    I'm going into town today, so I'll see if I can pick up one of these bagged foods. There will be an address of the manufacturer so you might be able to get some info from them.
    I'll definitely be interested in your reports.
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    Default Pressure Cooker

    Good Morning Winnie,

    I use the brand name Presto. It's a 16 quart pressure cooker. It uses a cam (or sometimes called bayonet) locking system rather than the type used by my mom which had swing up bolts to lock the top.

    Hope I've answered your question.

    Time to prepare for work so I will check back this afternoon when I return home. Have a great day.

    Harold

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    Senior Member Winnie's Avatar
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    Well I'm sorry Harry(hope you don't mind the familiarity) I ran out of time today and didn't manage to get to Aldi but I'll keep it in mind.
    Recession; A period when you go without something your Grandparents never heard of.

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    This sounds like the way they make MRE's for the military. Maybe the MRE manufacturer could help you.
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    Quote Originally Posted by finallyME View Post
    This sounds like the way they make MRE's for the military. Maybe the MRE manufacturer could help you.
    Good Morning,

    I may be badly mistaken but I was under the impression that most components packages in MREs had been gamma radiated rather than going through conventional retort. At one time I seem to recall that meals were cooked, placed in packages, then "zapped" with gamma radiation to kill all life.

    Perhaps they've changed their way of preparation as I have not kept up with the new era of MREs. If however they do use gamma radiation, then this method is far beyond the average household abilities.

    This is a good point that you have raised and worth researching regarding how the ARMY processes MREs. Thanks for taking an interest in this thread and taking the time to reply.

    Harold

    Harold

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    reclinite automaton canid's Avatar
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    i use autoclavable poly bags for the production of sterilized grain spawn in mushroom cultivation, and the principal is the same. untill full colonization, you have moist, cooked, sterile grain in a pressure canned bag, which must be safe from the introduction of any foreign contaminants for sometimes extended persiods of time.

    it works well, and would certainly serve for sterilized [pressure canned] food preservation, but my major concern would be checking integrity. with cans, you can pick them up, handle them, inspect them and they are vacuum sealed already as they come out of the cooker. with the you can seal them with the element on an impulse sealer, but you must inspect the seals, and this requires handling. during such handling, any imperfection in the seal can draw in contaminants. the major concern here being higher rates of food loss.

    with the mushroom spawn, this is not an issue, as the bags aren't generally sealed, but folded over multiple times and clipped or taped closed. i wouldn't trust that method for longer term preservation, for reasons which should be obvious.

    in a pinch, i've used reynolds oven bags for the same purpose. they are autoclavable aswell.
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    Quote Originally Posted by hunter63 View Post
    I do have several primitive bags belts and other buck-skinner gear made for "urban buffalo hide".

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    Quote Originally Posted by canid View Post
    i use autoclavable poly bags for the production of sterilized grain spawn in mushroom cultivation, and the principal is the same. untill full colonization, you have moist, cooked, sterile grain in a pressure canned bag, which must be safe from the introduction of any foreign contaminants for sometimes extended persiods of time.

    it works well, and would certainly serve for sterilized [pressure canned] food preservation, but my major concern would be checking integrity. with cans, you can pick them up, handle them, inspect them and they are vacuum sealed already as they come out of the cooker. with the you can seal them with the element on an impulse sealer, but you must inspect the seals, and this requires handling. during such handling, any imperfection in the seal can draw in contaminants. the major concern here being higher rates of food loss.

    with the mushroom spawn, this is not an issue, as the bags aren't generally sealed, but folded over multiple times and clipped or taped closed. i wouldn't trust that method for longer term preservation, for reasons which should be obvious.

    in a pinch, i've used reynolds oven bags for the same purpose. they are autoclavable aswell.
    I share your concern regarding integrity. It would be difficult to ensure that the integrity of the vacuum seal (which is only assumed), prior to autoclaving, survived the autoclaving process. In my test, the bag was vacuum sealed prior to placing the bag in the canner. When the "canning cycle" was complete and the cooker lid removed, and as one would expect, un-evacuated gases had expanded the pouch, hence the pouch was partially inflated. Similarly, as one would expect (assuming the integrity of the seal had not been compromised), the pouch "sucked back down" around the contents as the pouch and the contents cooled to room temperature. At first glance it would appear that the vacuum seal had not been compromised. Even over a year long period the vacuum seal "seemed" to hold because the pouch remained tightly adhered to the contents.

    One could make the argument that, if going on appearance the bag remained "sucked down" against the contents, the seal had not failed. I on the other hand can't keep from questioning if the physical properties, i.e. the plastic nature of the poly bag, in the presence of heat, cause the bag to have a "memory" thus giving the appearance the pouch retained it's vacuum seal.

    That being said, when I opened the bag using scissors, a sound was detected and the bag relaxed releasing its "grip" on the contents. Relaxation and expansion of the bag gives cause to suggest that a vacuum had remained over the year.

    What are your thoughts?

    Harold

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    One problem that may occur with canning in vacuum seal bags is you might be not getting all the air out. It won’t cause the food to spoil but it will cause oxidation which is bad for flavor, texture and nutritional value. When canning with jars you run a plastic spatula around the inside of the jar to remove any air bubbles in the food and when you pressure cook it the air in the neck is pushed out and replaced with steam so that when it cools there should be no or very little oxygen in it. I know I have canned meat and had air bubbles in it and when the can was opened it was obvious where the meat was in contact with air instead of liquid. We just picked out the bits that were discolored and ate the rest but that was only stored for 2 years. If you plan to store it long term the oxidation will only get worse.

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    reclinite automaton canid's Avatar
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    if vacuum was maintained [in your case, you can be sure it was] and the processing was sufficient to sterilize the contents, the food was sound.
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    Quote Originally Posted by hunter63 View Post
    I do have several primitive bags belts and other buck-skinner gear made for "urban buffalo hide".

  16. #16

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    Hi everyone I have Just joined this forum, after seeing that Harold had been pioneering in the canning bag field, I have info to assist in this, I had first experimented with canning in Bags really as a kind of fooling around as a kid nearly forty years ago! with less than ideal plastic and sweets in bags, this started because a friend had a bar of chocolate given to soldiers in the Boer war, and we ate it and it was good ish!, and since that time I became fascinated with preserving foods, I still experiment quite a lot and I found out a couple of Years ago that when you place a vacuumed and sealed bag into a pressure cooker the trouble starts at the end of the sterilizing/Cooking period, as the water vapor drops down in pressure there is a need to compensate compressed air for loss of steam until all has cooled down, this pressure of course must be safely regulated not to go above 10lb sq in at any time and is easy to do just by regulating and air flow in to a standard pressure cooker with an added air nipple fitted into the lid, the same safety device will relieve the pressure the same as it does with steam However it is wise not to rely upon this and to add an air pressure regulator set no higher than 11 lbs sq in, this has stopped bags from rupturing and has maintained a fairly strong evacuated appearance, apart from mylar requiring a robust dependable heatsealing in the first instance( hard to do with an iron!)this is the key I believe.

  17. #17

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    I know this is an old thread (and one wonders what happened to Harold...) but with plastics, high heat, and vacuum, you want to be absolutely sure the plastics are food grade and can take the abuse. Even sterilization bags may not be meant to hold food.
    BPA is a big thing now where plastics are concerned.
    Even canning jar lids contain some BPA (except for Tattler lids, supposedly).
    Home experimentation...for some things...just not for me.

  18. #18

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    I know what you mean "Low Key" I am very careful these days, and have been involved in injection mouldmaking as a toolmaker for around 30 years and I know that outgassing of PE is not likely at around 120c to 130c for max 30 mins, but 30c higher would produce ideal contaminating conditions, and pressure canning large Mylar bags of over 1kg mass would require 60 to 90 minutes indeed long enough for lower temperature reactions to start, however we consume PE dust frequently when eating foods from everyday bags, BPA is more associated with Poly-carbonate the plastic used in Drinks Bottles EEK! I am much more concerned with the fluoride/Chlorine/and many other contaminants in Water, even the skies are being Sprayed with Alzheimer producing Aluminium salts. we truly live in a poisonous environment never mind the Co2 scam the governments are pushing!.

  19. #19

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    I would think the problem with plastic bags is integrity over the shelf life. Something that is very easy to poke a hole into (and might in fact have microscopic holes without you knowing), is not a good vessel for food storage.

    Vacuum packed foil bags, however, should work, and are used commercially for lots of products.

    I wouldn't worry about BPA. Even the Europeans didn't ban it, and they ban everything. No hard science showing it is bad for you, and it lines the inside of every metal can of beans you've ever eaten.

    Always be wary of claims of danger from people trying to sell you the alternative.

  20. #20

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    The EU hasn't banned it, but they have very low allowable limits and are reportedly watching Low Dose studies in the US.
    There are a lot of things out there that the EU has banned that we continue to use here. Which in some cases isn't necessarily a bad thing. LOL.

    Not sure what the alternative is they are trying to sell.
    I didn't buy the Tattler lids cuz they're BPA free. I bought em cuz they are reusable.

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