Monday, October 24, 2011

Canning Tomatoes

So I tried my hand at canning this weekend. My mom got me a water bath canner and some canning jars for my last birthday, and she came over yesterday to help me can some tomatoes.

I did some research online about various tomato-based recipes such as salsa and spaghetti sauce, but in the end I decided to stick with the basics: tomato sauce and whole (skinned) tomatoes. This way, I can add spices or other ingredients at the time of cooking, which makes the canned tomatoes and sauce more versatile. Also, the addition of different ingredients can change the canning process, because the acidity of the food changes. So while I'm able to can tomatoes with a water bath canner, I'd have to be careful about adding peppers, onions and spices for a salsa, because if the acidity changes too much then I'd need to use a pressure canner.

The resource I used the most was the USDA Complete Guide to Home Canning. This online guide covers everything a beginning canner needs to know for putting up fruits, veggies, meats, pickled products, jams and jellies. There is a whole chapter devoted to tomatoes and tomato products, including some salsa and spaghetti recipes that are acceptable for water bath canning, but I still decided to stick with basic tomatoes for my first attempt.

This is a little over half of the tomatoes I started with.
I had hoped to be able to can some tomatoes from my own garden this year, even if it were just a couple of quarts. But the heat wave stunted production and I'm only now seeing a lot of tomatoes on the vines (and worrying that they won't begin to ripen before the cold sets in). So I had to buy tomatoes. The guide I mentioned gives an approximate weight of tomatoes needed for 7 quarts (a canner load) of tomato sauce and 7 quarts of whole tomatoes, so I made my tomato purchase based on those weights. I planned to put up 5 quarts of tomato sauce and 7 quarts of whole tomatoes (I only had 12 quart jars on hand), so I bought 45 pounds of tomatoes.

First, all the tomatoes had to be washed. I used a small amount of dish detergent in water when washing them, to remove any pesticides. I then rinsed them especially well to remove any residue from the detergent.

Next, the tomatoes were placed in a pot of almost-boiling water for about a minute, until the skins began to split.

We then took them out of the hot water and put them immediately into cold tap water. This makes the tomatoes easy to peel.

When making the tomato sauce, the directions in the guide book said to cook the tomatoes in a pot while mashing them. We tried this at first, but it was unnecessarily labor-intensive. So we began putting the tomatoes in the blender, and then transferring them to the pot for heating.

At the same time, we had another pot on the stove with boiling water in it. Once the tomatoes were ready, we would place a canning jar in the boiling water to heat for a few minutes, then remove it, add two tablespoons of lemon juice (for added acidity), and then fill the jar with tomatoes, leaving a quarter-inch of headspace as the guide directed.

The lids and rings were also soaking in warm (not boiling) water, to warm up the seals on the lids which helps them seal better. Once a jar was filled, we used a bubble remover to release any trapped air, then wiped off the rim and threads of the jar, placed the lid squarely on top, and then finger-tightened the ring over the lid.

The whole tomatoes were handled similarly, just omitting the blender step, and leaving a half-inch of headspace as directed by the guide. 

This is similar to what we used.
I have a ceramic-top stove which, for reasons discussed here, is not acceptable to use for canning. So we used a propane burner outdoors instead. The burner we have is part of a set sold for deep-frying turkeys. (We've never actually used it for that, but it's great for crab boils!) This thing burns like a jet engine, and heated the water in the canner to boiling in minutes. The only disadvantage is that it has a built-in safety feature--a timer that will turn the unit off after 20 minutes. We handled this by keeping a separate timer set for 18 minutes (just in case the timer on the burner wasn't accurate), and reset the burner's timer whenever our timer went off.

Tomato sauce cooling.
The tomatoes I bought filled more jars than the guide said they would. I wound up filling 7 quarts with tomato sauce. These were processed in the canner for 45 minutes. The whole tomatoes processed for 90 minutes. I don't know why the difference in processing times is so large; seems like they would be closer, since it's the exact same food, except one is blended and the other isn't. The whole tomatoes which were supposed to fill only 7 quarts, wound up filling the 5 quarts I had left plus 9 more pints! I double-checked my numbers against the guide, and I did what it said. For whatever reason, I wound up with a lot more jars than the guide said I would. I'm glad I had the pint jars on hand.

Once all the jars were finished, it was difficult to tell the difference between the whole tomatoes and the tomato sauce by just looking at them. So after they cooled down, I dated them and wrote on the lids what the contents were. Then before storing them, I removed the rings so I would have them for the next canning session.

Overall it was a good experience. I'm glad my mom was there to help me, because she's done it before. I got a little stressy a couple of times, but mostly I enjoyed the process. It took us most of the day to put up 12 quarts and 9 pints, but almost 4 hours was spent waiting for stuff to process in the canner. Maybe someone with more experience could do it more quickly, but I'm still proud of us.


  1. YAY you are canning too!!!!!!!!!

    I hope you try pressure canning!

  2. We've been trying it out as well. Just with apples, the first batch turned out perfect but the second (in 1 litre jars) looks more like applesauce.

    I think I left them in the pot too long.

  3. Anne, I definitely want to try pressure canning. I just have to get the pressure canner!

    Pimpley, my grandparents have some apple trees. I'll have to time a visit where I can bring home a bushel. I was checking out recipes online for cinnamon apples, apple pie in a jar, and just plain apples.


    We've been using --^ that recipe. The kids have been eating them as fast as I've canned them though.

    But it was simple and probably took about 20 minutes or so a batch, if I include the time to peel and cut them.

  5. That's a great website isn't it, Pimpley? I've found a lot of useful information on there.

  6. Kris....yay for your first time canning!!! It gets easier and easier each time you do it. Kudos to your mom for teaching you the right way. So glad you added the lemon juice. The whole tomatoes take longer to process because it takes longer to get the right temperature into the middle of the tomatoes. You are off to a great start...keep it up! (...and yes, get yourself a pressure canner too:-)

  7. It certainly is. I've never tried it before this year and the step by step with pictures was a big help.

  8. Thanks Dr Momi :) Now I've got to start building up a supply of jars and such. I keep seeing canning recipes I want to try.

  9. great job Kris! we love canning but unfortunately this just wasn't the year from our garden for more than just a few quarts and pints - thank goodness we are surrounded by farms to stock us up for winter!

    keep us updated on what you can and how, etc. - we all love to learn about what other people's methods are!

    again - great job!

  10. Thanks kymber! The heat was so brutal here this summer that nobody locally got a good tomato crop. There are one or two you-pick-em farms not far from me but they didn't have much to pick!

  11. craigslist.. a good place to keep an eye out for pressure canners. We got 2 old Nationals that are in perfect working order for an amazing price. It took a few months before we saw one listed, but well worth it. I'm still keeping an eye out for a Kwik-kook (which does not have a gasket.. and is what the neighbor used to teach me. His is ANCIENT.. and built to last many many generations. His old beast works like a dream.)

    Estate sales are another place to scope out. He snagged his kwik-kook for $5 almost 40 years ago at an estate sale.

    I'm a geek though.. and have an affection for old tools like that which were built to last.

  12. Thanks Anne. I do keep an eye on craigslist for anything canning related. There was an ad recently for 100 quart-size canning jars for $35 and I was excited to go get them, but my ever practical husband pointed out that they were in a town at least 90 minutes away, and after gas, vehicle wear and tear, spending half a day to go get them, bring them home and wash them, it wouldn't be worth it. I don't even know if the rings were included. But so far, no canners have shown up.

  13. Inviting you the Carnival of Home Preserving on my blog every Friday. Hope to see you there. Laura Williams’ Musings

    The most recent edition - - open until Thursday 6/7.