How does vacuum sealing work in jars?

[mike]

I picked up some food saver vacuum sealing canisters at a garage
sale, and can't figger out how they work???

If you stick a steak in a food saver plastic bag and suck out the
air, it works because the plastic conforms to the shape of the food
and excludes the air. Stuff in the meat can't get out, because it has
nowhere to go. There's no oxygen, because there's no space.
It's nothing to do with vacuum. There's no air because the plastic
is in continuous contact with the food. The vacuum pump merely facilitates
the process of making the bag contact the food continuously to exclude
air.

With the canisters, the vacuum pump removes maybe 2/3 of the air.
The rest is still in there. Volatile compounds in the food can still
evaporate into the space that has the partial vacuum.
It seems that the vacuum would accelerate desiccation of the food.
There's still lots of oxygen to react with the food.

Even if you could pull a perfect vacuum, it wouldn't last for long
as the volatiles exited the food into the space. That would solve the
oxygen problem.

So, why the heck would you want to pull a partial vacuum on a rigid
container of food? What's the advantage?

[Geoffrey S. Mendelson]

mike wrote:
>
> So, why the heck would you want to pull a partial vacuum on a rigid
> container of food? What's the advantage?

For example, look at your average container of beans, rice, (sometimes) pasta.
They contain eggs from insects. The eggs hatch and the insects eat the
food. If they are in plastic bags, they eat their way out, causing people
to think they ate their way in.

There are many ways of preventing insect eggs from hatching. In my experience,
the worst is a bay leaf, it never seems to work. The best, IMHO is storing
the food below 0F (which is colder than your average refrigerator's freezer).
The food must be at freezer temp for at least 48 hours, so I leave things
a week.

Some things are not practical to be placed in a freezer, or people don't
have one cold enough.

Storing them in a vacuum will do the same job. AFAIK the vacuum must be
maintained, if you open a vacuum sealed jar, take something out and close
it without another vacuum, it's not protected.

This only really works on things that are large enough so that the air
flows (on it's way out). It does not work well with powders.

You can still get some benefit by vacuum sealing powders, you remove oxygen,
which reduces the effect of time on them.

Bear in mind that no method of preservation is perfect or permanent, and you
chose the method that works best in a particular situation.

I remember in the 1960's being told to stock our shelters with bottles of
Yoo-Hoo and Twinkies, they would last forever. In reality, they both
had expiration dates and I doubt that if you found a stash from October
1962, they still would be edible. :-)

Geoff.


--
Geoffrey S. Mendelson, N3OWJ/4X1GM/KBUH7245/KBUW5379
It's Spring here in Jerusalem!!!

[George Shirley]

On 6/27/2013 2:19 AM, Geoffrey S. Mendelson wrote:
> mike wrote:
>>
>> So, why the heck would you want to pull a partial vacuum on a rigid
>> container of food? What's the advantage?
>
> For example, look at your average container of beans, rice, (sometimes) pasta.
> They contain eggs from insects. The eggs hatch and the insects eat the
> food. If they are in plastic bags, they eat their way out, causing people
> to think they ate their way in.
>
> There are many ways of preventing insect eggs from hatching. In my experience,
> the worst is a bay leaf, it never seems to work. The best, IMHO is storing
> the food below 0F (which is colder than your average refrigerator's freezer).
> The food must be at freezer temp for at least 48 hours, so I leave things
> a week.

I've done that for years too Geoff, keep the big freezer at -10F just
for that reason and for long term storage in the event of a power outage.

>
> Some things are not practical to be placed in a freezer, or people don't
> have one cold enough.
>
> Storing them in a vacuum will do the same job. AFAIK the vacuum must be
> maintained, if you open a vacuum sealed jar, take something out and close
> it without another vacuum, it's not protected.
>
> This only really works on things that are large enough so that the air
> flows (on it's way out). It does not work well with powders.
>
> You can still get some benefit by vacuum sealing powders, you remove oxygen,
> which reduces the effect of time on them.
>
> Bear in mind that no method of preservation is perfect or permanent, and you
> chose the method that works best in a particular situation.
>
> I remember in the 1960's being told to stock our shelters with bottles of
> Yoo-Hoo and Twinkies, they would last forever. In reality, they both
> had expiration dates and I doubt that if you found a stash from October
> 1962, they still would be edible. :-)
>
> Geoff.
>
>

I reckon that Twinkies would last forever and, at need, you could deep
fry them like they do at fairs and carnivals. I tried a Yoo Hoo when I
was about ten and didn't care for it. Grapette was drink of choice then
and, a bit later in life, the perfect soft drink for an adult was a shot
of 25-year old George Dickel over a single ice cube. Nowadays I drink
green tea or something similar. <G>

How y'all been doing up yonder?

George, getting ready to mow the !@#$ grass again.

[bigwheel]

The vacuum canisters work best for marinating meat. You can cut a 3 day
marinate time down to about 15 mins or less. Cabela's sells a version
which also tumbles. Very popular with some of the comp bbq cooks. It
also has a larger bucket than comes with the standard kits which will
hold a brisket flat or a couple of chicken halves. The standard sized
buckets are usually limited to chunks or cubes due to the size
constraints. To keep the weevils from hatching in grain and feed..a good
plan is to put the goods in a plastic bucket and place a chunk of dry
ice on top. When the dry ice dissipates it fills the container with Co2
which being heavier than air..will replace the oxygen and keep the eggs
from hatching. Gently attach the lid and seal the seam with duct tape
and it will keep a long time. Thats how the Mormon's do it..bound to be
right..lol. Freezing also works if you have room to do that.




--
bigwheel

[George Shirley]

On 8/7/2013 10:42 AM, Melba's Jammin' wrote:
> In article <51cc324f$0$51703$862e...@ngroups.net>,

> George Shirley <gms2...@att.net> wrote:
>
>> How y'all been doing up yonder?
>>
>> George, getting ready to mow the !@#$ grass again.
>

> Up younder like in Southrn Canada? Busier than a long-tailed cat in
> roomful of rocking chairs. My sister (the 82-year-old one) and left a
> helluva mess. My brother continues his slow decline and it is hard to
> watch him die by inches. My class reunion was last weekend and there
> were three consecutive parties. I just realized that my fair entries
> have to be delivered next Sunday and Monday (instead of Sun-Wed).
> Weather wrought havoc with crops and I've put up only half of my
> registered entries.
>
> Gonna take more than a candle, Jorge. Get the torches!
>
Been there, done that, one sister died of COPD at 83, smoked for nearly
70 years. Other one went into assisted living sometime last year, she
must be about 82 now, haven't seen her in years, her choice, so be it.

All we can do with elder brethern is weep a bit and remember the good
times, of which there were many with my big sister and a few with the
younger one.

I have no fair goodies to get ready but have been where that cat was due
to our garden trying to get everything ripe at the same time. Picked
about ten lbs of yellow squash today, one week after picking about that
much before. Cukes have slowed down as we haven't had any natural rain
lately.

Put up the last batch, four pints, of pear jelly, got two quarts and a
twelve-ounce jar in the canner at the moment of pear sauce with nutmeg,
another batch is ready to bring to a boil and jar. That will be last of
the pears we got for free. Well, almost, cost $24 of gas to get there,
still cheaper than 4 bucks a lb for pick-your-own pears and Miz Anne was
going that way anyhoo. All you can do kiddo is keep on going.

George, taking a short break