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Sep 10, 2010 09:23 AM

Jarring Tomatoes

I'm a newbie when it comes to jarring tomato sauce, in the past I've typically frozen a couple of small batches for the winter and that was it. This year I want to make
quite a bit more than usual but don't want to freeze it.

Basically I just want to cook down the tomatoes for 30-40 minutes (with nothing else besides some olive oil and salt) and jar them for future use in sauces, soups, etc...

Is there anything special I have to do when jarring?
Do I need to store them at a specific temperature?
How long will they last before they go bad?

I'm sure somewhere here there's a post about it but the terms; jar, can, tomatoes are so vague that there is so much that pops up when I do a search. If anyone knows of an old link I'd be more than happy to have a look at it.


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    1. re: jfood

      Ah darn, is it 100% imperative to boil the jars after you fill them? What does this step accomplish?

      Maybe I'll just freeze them instead.

      PS Thanks for the link.

      1. re: ios94

        canning and boiling the jars are the same word. the question becomes hot bath versus pressure canning. but without boiling and sealing the jars, it is no different from putting it in tupperware in the fridge.

        1. re: ios94

          The boiling step kills various microorganisms, many of which will spoil your food, others (like botulism) can spoil your day.
          If your food is relatively high acid (pH lower than 4.6), a simple boiling (100C) will do. Low acidity (above pH 4.6) requires a higher temperature sterilization (pressure canning).
          How do you know the pH? Simply follow the guidelines of the link (or other sources) on what to do.

          Tomatoes are on the fence, acid wise. I have a canning booklet that suggests a 1/2 tsp of citric acid (or an amount of vinegar or lemon juice) added to 1l of whole tomatoes to sufficiently raise the acidity.

          I'd say give it a shot and try it at least once. I'd suggest washing the tomatoes in water, cutting out the core, scoring the skin, and dropping in boiling water for a few minutes, easing peeling, then cook down.

          1. re: porker

            DEFINITELY read up on how to can tomatoes if you're going can/boil instead of freezing. Canning is not something to improvise/experiment with - not to sound alarmist but you could die of botulism if you don't follow proper protocol.

            That said, once you find good instructions for canning, it's not a big deal. It's easy.

            Good luck. (Actually, don't leave it to luck.)

      2. This web site is pretty much accepted as the definitive source for information on safely home canning:
        If you want your sauce to be shelf stable there are recipes and processes here to lead you through it. Going the water bath route is the easiest and cheapest way to get started since pressure canners require an investment of anywhere from $70-$300. Be aware that while a pressure canner can be used for pressure cooking, a pressure cooker is not recommended for pressure canning. Don't confuse the two.
        Tomatoes are on the cusp of the safe acidity range for water bathing so you'll need to use 2 tablespoons of BOTTLED (because the acidity level is consistent) lemon juice per quart jar, 1 tablespoon per pint jar. The lemon juice goes directly in the jars before you pour in the sauce. Don't use olive oil or other veg when making the sauce because those are low acid and every low acid ingredient you add lowers the overall acidity level more. You need a pressure canner when you add those ingredients. You can however, add dried herbs without it affecting the acidity.
        And don't use just any jars, use jars made specifically for canning like Ball and Kerr brands. They're tempered to withstand sharp temperature changes. Regular jars will crack and you'll lose your hard work.

        I know, it all sounds daunting but it's really not. Once you get the hang of it it goes quickly and you can really save money with in season produce and free up valuable freezer real estate for other things.

        1 Reply
        1. re: morwen

          I second everything morwen said, especially the part about not using oil. Powdered citric acid is a good substitute for lemon juice.

          Canning your own is fun, rewarding, and delicious, just don't cut corners. If you use the internet be sure to use official university or government sights for the best/safest information. Be careful about using stuff on someone's blog. It may sound like a tasty alternative or a shorter route, but it could kill you.

        2. Your "Home Extention Agent" should be in your phone book under the government pages or under "Agriculture" somewhere, and she should not only be able to answer your questions about canning, but be able to perhaps mail you something on "canning," which is what it's called out here in farm/ranch country.

          Personally, I have an excellent, step-by-step book I use, which I HIGHLY recommend for first-time canners and even experienced ones as it also has recipes.

          It's called, "Better Home and Gardens Home Canning Cookbook." The one I have is from the early 1970's. Here's a few tips that won't be in any books.

          1. Sometimes the jars will SLOWLY seal once you remove them from the canning bath. Only test to see of the seals take after they're thoroughly cool.

          2. Don't even have as much as one tomato seed, or a tiny splash of juice anywhere along the rim of your jars prior to sealing/boiling them or they will not seal.

          I've used some of my canned tomatoes as long as 9 years after I've canned them. I feel safe doing this because I'm pretty strict and careful during my canning process and take no chances with short cuts.

          You should be able to find that book online. I'll post a link.

          1. Here you go. Best $1.25 you could spend on a good canning book. And it's easy to use.


            1 Reply
            1. Wife and I put up about 20lbs of tomatoes this summer, in order to save them for the rest of the year. We used a method for whole tomatoes we found here on Chow ( Our logic was that whole tomatoes could be turned in to lots of things, but tomato sauce would always be tomato sauce. Some things we can share from the experience:
              Sanitize like crazy. Wipe down your kitchen with a bleach solution, and designate a clean zone and a discard zone. Likewise, make sure you are working with clean hands at all times.
              Boil your jars and lids for 5-10 minutes before you even start to use them.
              Some places will sell you a basic canning kit that includes a jar-lifter, a jar funnel, a spatula, and a magnet on a stick. You don't necessarily need these, but they make your life a whole lot easier.
              The recipe above recommends that you cook your tomatoes before you pack them, but since you're going to have to process them anyway, we didn't bother, and it seemed to work just fine.
              We used bottled lemon juice as recommended, and it seems to have done the trick, as far as pH goes. It did not affect the flavor.
              The jars that didn't seal were turned into spaghetti sauce and put directly into the freezer. The rest of the tomatoes are in the pantry, where we expect they will keep up to a year.

              11 Replies
              1. re: gilintx

                Boil your jars and lids for 5-10 minutes

                Actually most experts tell you to simmer the lids at 180 F, but not boil them. This will kill any germs (>160F will do this) and soften the seals slightly. Boiling can cause the sealant to soften too much leading to seal failure.

                This site ( only recommends washing lids and bands in hot soapy water.

                For more information, Google "boiling canning lids."

                The jars that didn't seal were...

                My point exactly.

                I only heat the lids and not boil them. I also cook the tomatoes first. If you put hot tomatoes in hot jars you get a head start on processing and ensure they are all heated properly. You still process for the whole time. I have never had a jar not seal in 25 years of canning. I attribute that to both of these steps.

                With all due respect, with all the steps you take with sanitizing, I am surprised to hear you skip this important step.

                1. re: al b. darned

                  Sorry, Al, I should have distinguished between lids and bands. I meant that only the actual screw-top would be boiled (I might not know my terminology here). The rubber bandish lid itself should not be boiled, but just put through the dishwasher or washed by hand, lest you melt the rubber.
                  I have tried both cooking the tomatoes, and not cooking them in two successive years, and have not seen a difference in the finished product. Why should I cook my tomatoes if I'm going to cook them in a water bath for half an hour anyway? This is not a facetious question; I'm seriously asking. Is it so that they're already hot when they hit the jar?
                  Bon chance on your jar sealing record. I would say that I've always had at least one jar of something that didn't want to cooperate with me. This applies to all my put-ups and pickles. At least it all got eaten.

                  1. re: gilintx

                    The guidelines I've read say sterilizing the bands is unnecessary, since they don't come in contact with the food.

                    As I said, cooking makes sure they are hot to start with. I usually heat the to boiling while the jars are sterilizing, so it doesn't take any ore time. It also draws out some of the water so I get more tomato and less juice. (And less of a chance of the dreaded layer of water on the bottom of the jar.)

                    1. re: gilintx

                      Packing raw tomatoes whole, crushed, or diced into jars with lemon juice and then covered with boiling water or tomato juice is a perfectly acceptable and approved way of canning tomatoes called a raw pack. If you're inundated with tomatoes it's a quick and easy way to get them put up. Depending on how many tomatoes you pack in the jar and any other tricks you use they may or may not float. In any case, floating is only a cosmetic issue and not a concern unless you compete with your canned goods.

                      I don't boil or simmer my lids. I keep a tea kettle of boiling water going to make sure I can raise the level in the canner if I have to. I put my lids in a small bowl and a few minutes before I fill the jars I cover the lids in hot water from the tea kettle. It's not necessary to sterilize the rings.

                      Seal failure is most often due to not getting the rims clean of residue, overfilling the jars leading to siphoning, or tightening the rings too much which can not allow air to escape and create a vacuum. Also disturbing the jars before they are cool can break the seal after they've been processed as can tightening down the ring too much after the jars have cooled. The rings are really only necessary for holding the lids in place while processing and many authorities recommend taking the rings off completely before storage. I don't have many seal failures (in 25 years of canning) but it's not unusual to have a couple/few a season when putting up a couple hundred jars.

                      1. re: gilintx

                        Gilintx, you ask why cook the tomatoes?

                        You don't have to as noted; that technique is known as raw pack. However, it does have some problems.

                        Firstly as you suggested, it's best to have the tomatoes hot as they go into the canner. The bigger the difference in temperatures inside and outside the jars, the greater the chance of breakage. Glass expands and contracts quite a bit according to temperature. If the insides and outsides of the jars are trying to do different things, well...

                        Secondly, the other problem I find with raw pack is that the tomatoes (or other fruits) tend to separate. You get the apparently dense stuff floating on top, and a bunch of liquid at the bottom of the jar. I *think* that this is because if you don't heat the fruit (tomatoes) sufficiently to break down the cell walls, they actually contain quite a lot of air. Because of this you also get more expansion and contraction of the produce being canned and thus more chance of leakage.

                        I used to think the less cooking of the canned produce, the better; but the more I can the less I think so.

                        1. re: Ferdzy

                          Assuming the jars are mason jars (tempered to withstand small temp differences),hot from sterilizing and sitting on a towel or newspaper, and the tomatoes are warm or room temp from being blanched and peeled, there's not enough of a temp difference to crack the jars.

                          Tomatoes will have the tendency to float or separate, cooked or raw, whole or diced, or juiced sometimes. My diced, seeded tomatoes always want to float and if I'm not entering them in a competition I don't worry about it. If I am, I risk smooshing the inside ones packing extra tight and use jars with shoulders to keep them from floating. Otherwise it's just a cosmetic thing. Shake the cooled jars to redistribute the tomatoes and liquid, although they will separate again eventually. Otherwise don't worry about it.

                          1. re: morwen

                            I hope somebody can help me
                            I can tomatoes with my friend on SUnday , we make 40 cook tomatoes and 40 jars of raw tomatoes, we didn't use lemon juice.We did sterilize the jars lids etc
                            I took my jars and put it in the car so I can boiled the jars (finish the process at my house) surprise next day like 7 jars star to pop up I resealed with new lids and boiled them again,since that day i have jars popping up , it is Tuesday and some keep popping up and smell bad I threw them away , some has bubbles but have the lids sealed correctly . Should I get rid of them too?.
                            only the raw tomatoes are the ones that are giving me the problems the cook ones look fine for now.
                            I read so many things about botulism that I am scared now , I want to throw the 70 jars away,, anyone has an advice please tell me and want to know which step I did wrong .
                            maybe driving them, the car motion?

                            1. re: erikape

                              The problem besides lack of lemon juice is more likely a result of the jars not being boiled immediately after you put the lids on. Did you wipe the rims of the jars to make sure they were clean before applying the lids? That could have been a problem too. When you raw pack tomatoes you still pour boiling water over them before putting the lids on so they are hot, and cooked tomatoes are already hot when you pack them. This is part of getting the temperature inside the jars hot enough so when you put the jars in the boiling water to seal they have a start on getting to the proper temperature all the way through to kill bacteria. Taking the jars home and leaving them at room temperature overnight before putting them in the water bath gave the bacteria a great environment to grow in. If your lids are popping and the tomatoes are smelling bad, if the bubbles in the sealed jars are moving or appearing to multiply, or the lids are starting to bulge, I would recommend throwing it all out. Those are all good signs that your tomatoes have gone bad.
                              Besides not using lemon juice, the biggest step you did wrong was not immediately waterbathing the jars. The motion of the car had nothing to do with it.

                    2. re: gilintx

                      jfood gets a cannot find for this url.

                      1. re: jfood

                        We corrected the URL, so it should work now.

                        1. re: The Chowhound Team

                          Thanks guys

                          salsa in the water bath and tomatoes and basil in the oven.