Tuesday, September 13, 2011

How To Can Your Own Tomatoes

Canning season has officially begun! I'm not an expert canner (by any means), but I have had success over the years with canning applesauce, diced tomatoes, tomato sauce, jams & jellies, pickles, and occasionally something special like apple pie filling or veggie broth.

Many folks are scared of canning, since botulism can mess you up... but it hasn't hit me yet, so I'm still feeling sassy. If I am canning something new, I do some reading online and make sure I follow a careful recipe, just to be sure.

If you are new to canning, tomatoes are a really a good place to start. The very high acid in tomatoes makes them much more safe to can than something less acidic (like green beans or something like that... then you need a special pressure canner, which would be rad and you would be very fancy). This year I canned up three different tomatoey products:
Plain ol' canned tomatoes (diced)
Tomato Sauce (for pasta!)
Roasted tomatoes with olive oil & salt (umami, baby!)

What follows are instructions on canning Diced Tomatoes:

You will need:
Two big pots -- Lots of tomatoes -- Glass jars, lids, and screw bands -- Canning tongs (optional) or regular tongs -- Canning funnel (optional) or a paper towel -- A knife -- A bowl for tomato tops, seeds, and icky bits -- Time!

1. First of all, let's be clear about this. You are going to need a lot of tomatoes. These little buggers really cook down a lot. I used all these tomatoes from my garden, plus more from my friend Jane the Farmer.

2. Wash your tomatoes off. They might be a little sticky or dirty or whatever, so give them a little tomato shower.

3. Get Chopping! Can you tell that I took this beautiful photograph at night? Also, can you see that you are in for a very messy job? Because you are!

What about the peels?
People who have more time than I do, and who are more fastidious than I am, will often take the time to peel their tomatoes (which is done by blanching them in boiling water). But seriously folks, this whole affair already takes hours... and I don't mind a little extra fiber!

To seed, or not to seed?
As for the seeds, I go back and forth. Sometimes I take the care to seed my tomatoes, and sometimes I don't. Seeding them is a benefit because the seeds provide a texture that you may not want, they can be a little bitter, and also the seedy goo adds a lot of liquid to the final product. Seeding them also takes a bit more time and (rather small amount of) effort, so if you are lazy, just skip it. Either way it's all yummy in the end.

4. Fill your giant soup pot with tomatoes as you chop - The excitement is building!

5. Prepare the jars.
You should have a bunch of glass jars with separate rims and tops (for a good vacuum seal).* Put them all in a big pot of water, covered by at least 1 inch. Bring to a boil, and then boil them for 10 minutes. This sterilizes the jars, so it's important! Once the timer goes off, just leave them in the hot water until you need them, and keep a lid on the pot, because you will need to get this water boiling again soon.

As you can see in this picture, I finally splurged and got a proper canning pot - it's huge and has a special rack on the bottom, which keeps the glass off the very hot bottom of the pan. It was only $25 at the hardware store, so if you enjoy canning, I really recommend it. If you don't have such a thing, you can also just put a dish towel on the bottom of the pot. It will work just as well!

6. Cook up the tomatoes!
I bring them to a boil (covered), then remove the lid and lower the heat to a simmer, for about 30 minutes. This can be done side by side as the jars are cooking up.

When the tomatoes are done, you may have a lot of liquid in the mix. You can leave it in, or you can decant some of it. I just press the ladle down gently (pictured) and take a few ladle-fulls out. (tomato juice!). Whether or not you get this depends on how much water was in the tomatoes you started with.. you didn't do anything wrong if you didn't get any, and you didn't do anything wrong if you end up with a lot of water to scoop out. Also, like I said, it's fine to leave it in there.

7. Pour the tomatoes into the jars! (ack, no picture for this step!)
Carefully remove the jars from the hot water (pouring any hot water back into the pot). Now, use a ladel to pour the tomatoes into the jars. I use a special canning funnel, which is a big help. It lets you be a little sloppy, while still keeping the rim of the jar clean, which is important for a good seal. You want to leave about 1/4 - 1/2 inch of space at the top of the jar. If you don't have a canning funnel, pour carefully, and then when you have filled all the jars, use a damp paper towel or dishcloth to wipe the top rim on the jars completely clean.

Note: the tomatoes are hot, as are the jars, so please be careful!

Put the lid on each jar and screw on the band tightly.

8. Process the jars
First of all, double check that your lids are screwed on nice and tight! Now, carefully lower the hot jars of tomatoey goodness back into your giant pot of very hot water. (*Note: I use canning tongs, which are so rad, and a great idea if you plan on doing more canning in your life. Otherwise, you can be very careful and use regular tongs. But please remember, you are dealing with boiling water, hot tomatoes, and glass jars... so you really do need to be careful!)

Once again, have a rack or a dish towel on the bottom on the pot to keep your glass jars away from the bottom of the pot.

Bring the water to a boil, and then lower to a low boil (more than a simmer), for about 25 minutes. Once the beeper goes off, remove the jars (again, be careful!) and set them on the counter to cool off. Now you can go in the other room and listen to the world's most glorious sound: the pop-pop-pop of the vacuum seal setting in!

Once the jars have cooled, double check to make sure that the "button" on the top of the lid has been sucked down. If you can still pop it down, then your seal didn't work. But don't cry. Just put that jar in your fridge and use it sooner rather than later. See, it wasn't so bad.

9. Gloat!
Don't forget to gloat! I like to leave all my jars out on the table for a day or two to bask in the beauty of such industry and hard work. Then I put them away for the winter in the cupboards. Sometimes I give some away as christmas presents, sometimes I keep it all for myself! :)


  1. Gloating is the most important! I see you have perfected the art ;)

  2. Step 9 is my favorite, or maybe step 10 when you get to eat them!

  3. I have always been too scared to can things. Maaaaybe your post has made me less scared!

  4. So much tomatoey goodness! Well done, Amey!

  5. Anonymous9:59 PM

    I love this post! Canning is the highlight of my summertime and tomatoes are the one fruit I have yet to tackle. You outline the process perfectly! Now I just need to steal some tomatoes from a garden (Kittee's, perhaps?)!


I love comments, they really make my day! Thanks for reading my blog!