Air in jars when canning

[Bill Velek]

I was just looking through my Ball Blue Book again, and came upon some
directions that I had either missed or had forgotten when I canned some
meats earlier this year. It says to be sure to get all of the air
bubbles out of the jars before canning, but it doesn't explain why.
I canned some meats which no doubt had some air bubbles remaining
inside the jars; e.g., uncooked bacon, and raw chunks of sirloin steak,
and ham, etc. The jars did not break, so that wasn't a problem, and
other than a few sealing problems which were apparently caused for
another reason which has been corrected, they sealed okay. Now, since
there is always air in the headspace, what is the difference if there
is also some air gaps or spaces further down in the jar, in between
the chunks of food. Is there any risk or danger in eating that food,
or is the problem more a matter of aesthetics (discoloration or taste)?
Why? Any info will be appreciated.

Thanks.

Bill Velek

[TDKozan]

It's mostly to get the correct headspace on the jar.

TK

"Bill Velek" <ve...@cyberback.com> wrote in message
news:385A6A69...@cyberback.com...

[The Condor Chef]

In article <385A6A69...@cyberback.com>,
Bill Velek <ve...@cyberback.com> wrote:

>I was just looking through my Ball Blue Book again, and came upon some
>directions that I had either missed or had forgotten when I canned some
>meats earlier this year. It says to be sure to get all of the air
>bubbles out of the jars before canning, but it doesn't explain why.

Best guess; To ensure an even temperature throughout the contents of
the jar. Air conducts heat differently than liquid.

The Condor Chef

--
"Both oligarch and tyrant mistrust the people,
and therefore deprive them of their arms."
-- Aristotle, "Politics"

Sent via Deja.com http://www.deja.com/
Before you buy.

[ma pickle]

The air bubbles can add to the headspace. If you headspace is off the jar
may not seal properly.

[The Condor Chef]

In article <9_N64.82839$C7.35...@news1.teleport.com>,
"ma pickle" <mapi...@teleport.com> wrote:

> The air bubbles can add to the headspace. If you headspace is off the
> jar may not seal properly.

Yeah, that too.. ;)

(Thanks, Ma)

[Bren]

Bill Velek wrote:

> I was just looking through my Ball Blue Book again, and came upon some
> directions that I had either missed or had forgotten when I canned some
> meats earlier this year. It says to be sure to get all of the air
> bubbles out of the jars before canning, but it doesn't explain why.

One possibility that comes to mind is heat penetration to the centre of the
jar. Since air is basically an insulator, large amounts of it trapped
within the body of the product could slow the rate of heat transfer,
reducing the final lethality at the cold spot in the can/jar. Vegetables
which have air spaces between the cells may need to be blanched first to
de-gas them, otherwise the heat transfer rate is slow. The headspace does
act as an insulator but this is taken into consideration when deriving the
process.