Hold on to your socks! My newest toy!

[Chief Longwind Of The North]

So you could impress your friends by plunging your hand into a vat of boiling water!

I'm thinking that as the gasses boiled out of the fluids in your had (as it's in the same vacuum), you'd suffer some painful emolisms in the localised area that's in the vacuum. I don't think I'd want to put my hand in that thing.

Seeeeeya; Chief Longwind of the North

 

[Chief Longwind Of The North]

Does this mean your chili, marinara sauce, gravy, soup, etc. can be stored at room temperature?

No! High temperature is what kills organizms, not the boiling action. In fact, removal of the air is essential for the organizm that produces the botulism toxin to survive, as it is an anerobic bacteria.

If everything is hot and sterile when the vacuum is applied, you are essentially "canning" and the food is then safe. If the food is sealed, and then cooked to temperatures, in the sealed bag, sufficient to kill all micor-organisms, then again, the food should be safe to stor at room temps.

Also remember that plastic is not a seal againse small-molecule gasses, such as hydrogen. If fats are stored in plastic, hydrogen molecules can be exchanged from the outsid air to the interior of the package, causing spoilage of the fat. Other gasses may be able to pass through the plastic as well. So plastic bag storage should be considered only for the short term.

Seeeeeeya; Chief Longwind of the North

 

[Andy M.]

No! High temperature is what kills organizms, not the boiling action. In fact, removal of the air is essential for the organizm that produces the botulism toxin to survive, as it is an anerobic bacteria.

If everything is hot and sterile when the vacuum is applied, you are essentially "canning" and the food is then safe. If the food is sealed, and then cooked to temperatures, in the sealed bag, sufficient to kill all micor-organisms, then again, the food should be safe to stor at room temps.

Also remember that plastic is not a seal againse small-molecule gasses, such as hydrogen. If fats are stored in plastic, hydrogen molecules can be exchanged from the outsid air to the interior of the package, causing spoilage of the fat. Other gasses may be able to pass through the plastic as well. So plastic bag storage should be considered only for the short term.

Seeeeeeya; Chief Longwind of the North

I was reacting to Robs statement about bagged tuna and MREs - both foods that are kept in retort bags at room temp.

 

[Greg Who Cooks]

What's different about MREs? I presume they last a lot longer. Different type of plastic? Metalized or something?

 

[GB]

What's different about MREs? I presume they last a lot longer. Different type of plastic? Metalized or something?

They are processed at high temp/pressure which is what makes them safe for shelf storage.

 

[Greg Who Cooks]

But doesn't the hydrogen still get in?

 

[GB]

But doesn't the hydrogen still get in?

Nope, these bags are designed for this very purpose.

 

[PrincessFiona60]

But doesn't the hydrogen still get in?

I believe that is what the Retort bags are made to do, stop the oxidization of fats.

 

[FrankZ]

So I have been sitting here reading a ton of stuff about this, and trying to separate Internet facts from real facts.

But, as I understand it, one could stick food in the bag, vacuum and pressure can and have shelf stable foods in nonbreakable, flexible containers, at home.

That would be awesome.

Where's our canning experts for comments?

 

[Chief Longwind Of The North]

It may be that the MRE plastics are metalized, or are made from a plastic that has a tighter molecular matrix than the poly-styrene. I worked with poly-styrene containers that were used to house lead acid batteries. We couldn't use metal containers because they woud trap the hydrogen, creating an explosive environement. The plastic containers allowed the hydrogen molecules to pass through, thus negating the hydrogen build up (lead acid batteries outgas hydrogen gas when under use. Some of the water is electolysed as current runs through the electrolyte solution.).

I am not an expert on most plastics, but do know that we had to take special precautions in the packaging process to produce a safe product for our customers.

We have any chemists around here?

Seeeeeeya; Chief Longwind fo the North

 

[FrankZ]

It appears the retort pouches (MRE pouches) are plastic and metal laminates.

 

[Andy M.]

It appears the retort pouches (MRE pouches) are plastic and metal laminates.

So back to my question. If you vacuum pack food in a retort bag and sous vide it, is it shelf stable?

 

[FrankZ]

I am guessing sous vide is too low of a temp...

Canned food needs to hit 121C (251F) to be safe.

 

[Rob Babcock]

So back to my question. If you vacuum pack food in a retort bag and sous vide it, is it shelf stable?

No, you have to process it in a pressure canner at 15 psi. This heats the contents to 245 F (iirc) which is high enough to kill the spores that cause botullism.

And yeah, the retort pouches have a layer of aluminum.

 

[Andy M.]

No, you have to process it in a pressure canner at 15 psi. This heats the contents to 245 F (iirc) which is high enough to kill the spores that cause botullism.

And yeah, the retort pouches have a layer of aluminum.

Thanks, Rob and Frank.