Canning 101 -- Why 2-Piece Lids?

      Everybody raise your hands that has canned something in a 1-piece lid.  You know, you saved the jar and it's lid, reused it to can your jelly, and it worked good -- a nice seal by the sound of the "pop" when you opened it.  I did it.  Then I found out why I shouldn't.

     When a manufacturer cans ....say...their artichokes in a jar, they fill that jar right up to the very top with liquid and then use a device to create a vacuum that sucks any air out of the jar. At the very same time, the lid is put on.  This is all done by machine.

     In home canning we have no devise to get all the air out of the jar.  This is where a two-piece lid comes in.  By a two-piece lid I mean the canning lid and the screw band.  When in a water bath or pressure canner, a two-piece lid allows air to escape from the jar.  This is why you only put the rings on to finger-tip pressure -- not tight.  You want that air to escape. 
Reusable Tattler lids are also a 2-piece lid, which you put on to finger-tip pressure, but then you have to remember to tighten the lid when it comes out of the canner to get a nice seal.

     So what's the big problem with oxygen in your canned jar?  Well, some bacteria thrive on it, but that's not the main reason to make sure there is no oxygen in your jar. The bacteria can be controlled with acidity.  Mold is probably the main reason to get the oxygen out of your jar.  Molds require air and water to grow.  The other reason is food quality.  The color, flavor, and odor of the canned goods are all compromised when there is air in the jar. 

     This is a start to a series of Canning 101 posts..I can find time to write them now, ..... in the middle of canning season.....not so much. :-)

Tsk, Tsk miss jean.  Yes I did it.
A just opened jar of strawberry jam from 2 years ago.
No I'm not throwing it away, but, .....not doing it any more.


Linked To: Homestead Barn Hop


Melodie said...

I have not done this but I just hate not reusing some of those jars! Some are so cute it is hard not to want to reuse them for jelly and the like!Some of the really cute ones,that I can not possible throw away, I use to store my dried herbs in.

Carolyn said...

Guilty here also. But since I've been able to accumulate enough "real" canning jars & lids I haven't done it in years. Now I just find something else to do with those jars, like store spices or nuts or seeds.

pattib said...

Oh! Great to see you start this series. Canning is foreign to me, so maybe you'll get me going!

Unknown said...

Thanks for that much-needed info! My mother did it but always cautioned me not to re-use the single-lid, no further explanation. That makes great sense!
Question for you: Can you safely re-use the center piece of a 2-piece lid if it shows no dents of misconfiguration?

Kim@stuffcould.... said...

I have not canned anything but my Dad has...he does not can jelly though

Candy C. said...

Great series! Thank you so much for sharing your expertise! :)

dr momi said...

Melodie....I love to save cute jars for odds 'n ends too. I have to save them quickly and get them out of sight before my husband ends up chucking it though LOL.

Carolyn Renee....same thought here Carolyn, I'll just use the cute jars for something else.

pattib....I hope you start canning. Lots of fun and very rewarding! I gave a lot of canned goods to friends for Christmas....everyone loves it.

Ronda....reusing a lid I think is setting yourself up for a lot of jars not to seal. It's a lot of work to get the food ready to can. If they don't seal -- super bummer. Don't reuse single use canning lids. With that being said, I love the tattler lids. These can be, and are meant to be reused.

Kim....knowing someone who cans and shares with you is a blessing!

Candy C....Thanks, I hope to do a lot more of them.

Michaele said...

I love canning and think the pop the lids make as they're cooling is one of the most satisfying sounds I know : )

Mama Pea said...

My folks knew a couple who loved dry roasted peanuts and ate a lot of them. The peanut jars have the rubber seal inside the lids so this lady always saved those jars and used them for most of her home canned goods. The couple lived to a very old age . . . but I'm way too much of a scaredy cat to do something like that. New two-part canning lids for me every time! Great series you've started. I'm looking forward to more of it.

Unknown said...

Oh, I've done it too..oops!
Thanks for the excellent information..we all need reminded now and then.

dr momi said...

Michaele....lids sealing is a very satisfying sound!

Mama Pea....around here people save those kinds of jars and then sell them at rummage sales. People scarf them right up! And you're right, you don't hear of people know they are canning with them, but why risk the quality of your food? It's a lot of work (fun work) to get that food canned, why risk having to throw it all away?

Simply Scaife Family....Haha, thanks for being so honest :-)