jerryc41 Loc: Catskill Mts of NY

A YouTuber in Scotland posted a video showing how he can use regular jars to vacuum seal food. I don't think he's right. Be patient with my description.

He uses one of those common vacuum sealers that use plastic bags to create the vacuum and seal the bag. He uses that along with an accessory, a 6" diameter plastic jar that connects to the vacuum machine with a hose. For vacuum storage, he uses regular food jars that he buys at the supermarket, but they must be the kind that has the vacuum-indicating section on the top. You know how that works. If there is a vacuum, the top is pushed down slightly. If the seal has been broken, the center of the lid is raised. Never buy a food product it the top is bulging!

He puts the food into the jar, screws on the lid and puts it into the plastic vacuum jar. After putting the lid on that, he operates the vacuum machine until it shuts off. Then he explains what's going on. There is a vacuum inside the big plastic container, and air pressure outside it. When he removes the top, the air pressure will rush inside and push down the top of the food storage jar. Then, he says, it is vacuum sealed, and that sunken top is the proof.

I don't buy it. The glass storage jar is sealed. How can that pump create a vacuum inside it? I can understand how the outside air pressure can push down the top of the jar, but that doesn't create a vacuum inside it.

If I can find that video again, I'll post a link.

EDITED: Here's a woman doing the same thing. By the way, we had two of those food storage vacuum machines, and they both stopped working way too soon. I'm not going to try again.

https://www.youtube.com/watch?v=aQAadpgIpJQ

Longshadow Loc: Audubon, PA, United States

It can if the lid is just a bit loose. Pressure inside the jar will push out the air when the container the jar is in is evacuated container, the lid re-seats and the lid seal will close. Kinda like a one-way flapper valve. A TIGHTLY sealed lid will not.
Most likely works best with the canning jars with the separate top seal disk and the threaded retaining ring.

fourlocks Loc: Londonderry, NH

Longshadow's absolutly corrrect. I suppose there's a slight possibility the jar lid is loose enough to allow air inside the jar to escape and equalize with the low pressure created inside the container and then when the container is opened, the higher outside pressure forces the lid into an air-tight seal. My wife's 2-piece canning jar lids have a rubber 0-ring seal that might allow that to happen. I wouldn't want to rely on it, though.

Longshadow Loc: Audubon, PA, United States

As long as the lid dimples down it should be good. Might have to try a second time if the lid seal is too loose or too tight.

JBRIII

It's not really a complete vacuum if it's caused by the hot, near boiling, liquid being put in the jar and sealed. When it cools it creates a partial vacuum caused by the lower temp of the remaining gases and water vapor in the jar. Since everything was boiling just prior, it stays sterile unless the seal breaks or some extremely old capable of surviving boiling was present at the start.

True glassware capable of with standing full vacuum is very heavy and thick. Even then a weak spot, bad scratch, etc. can lead to explosive decompression, bomb and flying glass shards!!

Longshadow Loc: Audubon, PA, United States

None the less a vacuum for the intended purposes.
It isn't intended to be zero Pa. <100 Pa to 0.1 Pa is a medium (fine) vacuum.
1 atm is 101325 Pa.

Suffice to say "In engineering and applied physics on the other hand, vacuum refers to any space in which the pressure is considerably lower than atmospheric pressure."

How about the vacuum food sealers that suck all the air out of a plastic bag. They don't get to a "perfect vacuum" either. But they are considered vacuum packed.

Exactly how persnickety and detailed do you want to be?

Wkndr Loc: Sitka, Alaska

"we had two of those food storage vacuum machines, and they both stopped working way too soon"

We had three, two were free because they stopped working, wouldn't make a very strong vacuum, as did ours that we bought. Finally figured out that putting the upper and lower gaskets under running water and putting them back wet made the machines work.

sjb3

The video on this subject that I watched not long ago originated within the UK (Scotland, I think) and the man demonstrated the recycled jar-inside-the-larger-one just like Jerry described. The man also mentioned that vacuum sealing via the various machines on the market didn't take the place of actual canning, i.e. whatever was sealed inside (if it was perishable) still had to be refrigerated or frozen like with the vacuum bags. We have a 10-year-old Foodsaver with the little accessory cap that allows us to long-term store rice, beans, pasta, etc. In wide-mouth Mason jars. The hose for it plugs right into a dedicated port on the machine, the various jars are neatly lined up on the pantry shelf and the contents stay fresh and ready-to-use for a longer time.

SnoShuSam Loc: Texas, (ex Virginian)

I remember my mother and my aunt, fathers sister, canning tomatoes, beans, peas, squash, and other vegetables and fruit (pears and peaches) and sealing the jars with wax poured on the top of what was in the jars. I also remember putting tops on the mason jars, quart size and waiting for the tops to seal. If we had one that didn't pop we put them in the refer. The jars that popped were stored in the basement till needed. Each laundry day my Mom would check each of the jars to make sure all the seals were holding I remember eating chili during the winter made with her tomatoes. her pears and peaches were terrific as well.

Longshadow Loc: Audubon, PA, United States

JBuckley

Me, either.

There are vacuum jars that have suction devices that can remove air, from inside of the jars that are used.
(They are purchased separately from the vacuum/sealing devices.

Harry02 Loc: Gardena, CA

Beat me to it ...
The old canning, with the boiling water, sterilizes the contents.
He doesn't do that, so he;s just jarring un sterilized food.
LWAYS check for green fuzzies in the jar!

SteveFranz Loc: Durham, NC

I've done that many times with mason jars. Makes a nice seal. Not a high vacuum, but enough to keep food fresh and keep the bugs out.

wmurnahan Loc: Bloomington IN

You can but it is not "canning" level of preservation, it is Tupperware level preservation,

Longshadow Loc: Audubon, PA, United States