Tomato canning confusion

[tooticky]

I've just canned a bunch of whole/halved tomatoes, carefully following instructions regarding safety (added lemon juice, poked into the jars with chopstick to remove air bubbles, processed in water bath for recommended length of time).

I'm confused because of the warnings about the fact that pockets of air can allow bacteria to breed. After the jars came out of the water bath there were many more bubbles than when they went in. Also, some of the jars had a lot of air at the top.

I'm also wondering about the fact that the directions all seem to say to leave a 1/2" of headspace at the top of the jar. Wouldn't that be air that the bacteria could breed in?

Scratching my head here! Are these tomatoes going to be safe to eat?

Thanks for any advice!

[snugglebug14]

to the best of my knowledge the pressure from the canning process forces any air out of the jar which creates the vaccumm seal between the jar and the lid. So what you see as "air" is actually just empty space which is why you hear the popping noise when you break the seal. anyone with additional info can feel free to correct me if I'm wrong

[kjbrown92]

I never heard of adding lemon juice. But the rest sounds right.

[dlm194]

That air is called headspace. It's typically used in commerical canning to allow heat to penetrate through the can better (if the can were completely full, it would not allow any movement in the can and decrease the heat penetration).

Not knowing your exact process or pH in the can, I cannot completely comment on the safety in the can but tomatoes are acidic. Usually canned foods have the concern of contamination with botulism which cannot survive in an acidic encvironment (pH 4.6 specifically).

[tooticky]

Thanks for the replies.

I had left a 1/2" for headspace. Now some of the jars have over an inch of space at the top, others less....

I have decided to turn the jars that had tons of space at the top into tomato sauce and reprocess.

The others I will assume are safe since they are sealed and since I increased the acidity with the lemon juice.

Thanks again.

[mamadelbosque]

We had this problem the first batch or two of diced tomatoes we did last year. We learned to really pack them down tight (like, smashing them down with a wooden plunger thing) in order to keep from having 1-2" of 'head space' when finished. But, we pressure can our tomatoes so it never bothered me safety wise.

[elanorh]

Originally Posted by dlm194

Not knowing your exact process or pH in the can, I cannot completely comment on the safety in the can but tomatoes are acidic. Usually canned foods have the concern of contamination with botulism which cannot survive in an acidic encvironment (pH 4.6 specifically).

Actually, tomatoes are a borderline food. There have been cases of botulism from canned tomatoes, which is why the recommendation now is to either acidify and water bath for the appropriate recommended time for your altitude, OR to pressure can them so that the heat they're canned at is sufficient that botulism isn't a concern.

There are many factors which can affect the acidity of tomatoes - ranging from soil type, to ripeness, to tomato variety (some have more or less acidity), to whether they have been frosted.

It's best to either pressure can them, or use the lemon juice in the ratios recommended by the USDA's food preservation guide, or Ball Blue Book (website: homecanning.com). The recommendations were changed after 1988, so recipes from before then should be checked against the current recipes; if the acidification is not the same or greater, then the more recent, approved recipes should be used.

OP - headspace is to accomodate how much the food will expand during the processing time. Jams/jellies don't expand much; corn expands a lot - apple sauce or tomatoes require the 1/2 inch. You need to adjust your heat once you've returned your waterbath processor to a boil (with the jars in it) - you want to maintain a boil but not a HARD boil which can cause the jar contents to bubble over. You would probably still end up with a good seal, but would lose some of the juices or etc. (as you discovered). What you've canned this way, as long as the seal is good, should be fine - but you may have some discoloration on the exposed part which is at the top of the vacuum seal of your jar.

Here's the link to the USDA information about canning tomatoes:
http://www.uga.edu/nchfp/how/can3_tomato.html

ETA: Half inch headspace is the middle ring around the top of the jar opening; one inch is all the space where the ring lines are, open. In case anyone doesn't know how to gauge that.....

[lil_miss_understood]

is there anything you don't know, elanorh?

[Owen'nZoe]

To elanorh's great post, I just wanted to add that when I do my tomatoes, I've noticed that there are tons of little bubbles in the jar when I take them out of the water bath. The bubbles don't seem to get stuck against the side of the jar like the ones that get trapped there when you fill the jars do; they just rise to the surface and dissipate.