The Skinny on Fermentation: Un-canning Tomatoes

{Looking for something a little unconventional to do with summer’s last onslaught of vine-ripened tomatoes? Contributor Jesse Frost of Rough Draft Farmstead has been doing some crazy experiments in his fermentation lab that you won’t want to miss! Also, Hannah & Jesse are on the lookout for some farmland, so drop them a line if  you have a lead.}

My wife and I enjoy canning our extra tomatoes for winter soups and sauces, but read almost any canning publication and they will often be surprisingly frank with you about how much canning negates a fruit or vegetable’s nutritional properties. We boil the canned tomatoes for a long time in order to avoid things like botulism (and rightfully so), but in so doing, we destroy a whole layer of beneficial nutrients. Essentially, we pasteurize it. Fermentation, however, not only retains a food’s nutritional value but boosts it, and often preserves vegetables for at least as long as canning, if not longer. Also, due to the acidic environment created by fermentation, and its natural ability to detoxify foods, bacteria like botulism cannot thrive and are not an issue. As Sandor Katz puts it in his newest book, The Art of Fermentation, “…it is improperly canned foods, not ferments, that can harbor botulism.”

So in light of preserving a healthier, safer form of tomato this year, I decided to try fermenting some. Since I’d never fermented tomatoes for anything other than tomato wine or to save seed, I did two batches to be sure of the results, and wound up with 8 quarts of fresh tomato sauce.

What you’ll need:

(makes 4 quarts)

-6-8 lbs of fresh tomatoes––preferably organic or non-sprayed

-2 tablespoons sea salt

-1 cup water (avoid tap water as it typically contains ingredients like chlorides which will slow or stop the fermentation. I get water from our local nutrition center for .39¢ a gallon)

-2 gallon, wide-mouthed clay crock or glass jar (avoid plastic or coated ceramic)

-Cloth to cover fermentation container

-String to tie cloth onto fermentation container

-4 1qt mason jars

-Olive Oil

-A spirit of adventure

Recipe:

Remove the core from tomatoes and cut into medium-sized chunks, slightly larger than bite-size. You do not need to remove the skin. Place in large crock or jar––fill no more than three-quarters full, less is fine. Add any garlic or peppers you would like––ferments are like soups––be liberal, they’re fairly forgiving. Me? I threw in a couple jalapeños. Combine salt with water and pour overtop. Massage tomato mass with hands until juicy, about one minute. Tie cloth over vessel to keep bugs out and stir at least three times a day, though more is better.

I recommend keeping this particular ferment away from your daily life––in a basement or mudroom or anywhere with good airflow––as part of they way you know it’s working is the unearthly smell it produces, just warning you. Here’s where you’ll need that spirit of adventure as the smell lasts for about 12 to 24 hours and you have to stir straight through it. It will soon be replaced with the lovely aroma of fresh tomato sauce, however––I promise, so be brave.

Once the odd smell is gone and it begins to smell fresh again, and the bubbling subsides almost entirely, you are now ready to can (about 3-5 days altogether, at least 1 1/2 full days after the odd smell dissipates). Ladle the finished ferment into four clean mason jars, leaving an inch before the top of each jar. Wipe the rim clean and gently pour a thin layer of olive oil overtop to keep oxygen off and mold from forming (not my invention, but a pretty nifty trick!) then place the lid on the jar. If it’s still bubbling when you have to can, don’t sweat it. Just make sure to release the pressure every few days for a week by unscrewing the lid of each jar until it makes a hissing sound. Otherwise, it could explode the jar––seriously––but this is a common reality with fermentation.

If you follow these guidelines and find mold or growth at any point before or after fermentation, simply scrape it off as soon as you see it. I found a light white film in my first batch because I had forgotten to stir for twelve hours but scraped it off, no problem. Mold can happen in nearly any ferment. Don’t be afraid of it unless it’s anything but white (which I’ve never ran into), but which you can also just remove. My understanding is colored molds are proceeded by the white molds, and white molds (in this case) result from too little stirring. Just check your ferment often and be diligent about stirring or removing any unwanted growth.

And that’s it. It takes longer than canning but less attention, less work, less energy, and the tomatoes are preserved healthier than when they started. I’ve been really pleased with the immediate results. If the ferment holds, as it seems to be doing perfectly, you can bet we will likely be fermenting much of our tomato sauces every year, and I feel confident we’ll be getting more nutrients this winter than ever, if it makes it to winter that is. We’ve already eaten nearly 2 quarts. Oops.

How to Use:

Employ your fermented tomatoes to marinade meats or vegetables; blend with fresh celery and drink a little as a tomato juice (or add some vodka and you’ve got yourself a Bloody Mary!); make a creamy tomato soup, or use it in place of wine in certain pan sauces. Today I reduced some by half and poured it over fried rice. It was absurdly good. I also made a makeshift barbecue sauce—lots of potential there. Feel free to share your own fermented tomato recipes or ideas you have for its uses!

You can post your questions and comments here, at roughdraftfarmstead.blogspot.com, or contact me at roughdraftfarmstead@gmail.com.

Behind on your fermentation reading? Catch up by reading Jesse’s introduction post.

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Author:Jesse Frost

Although born in Colorado, Jesse spent his formative years in Richmond, Kentucky. After high school he received an opportunity to cook at Le Relais Restaurant in Louisville under Chef Daniel Stage where he spent two years learning the importance of local produce before moving to New York City. While there, Jesse found himself managing a small wine shop in lower Manhattan. Specializing predominantly in organic, biodynamic, and sustainably-produced wines, he discovered a fondness for natural fermentation and farming. After four years, he left the city and returned to Kentucky. A two-season internship at a small farm in Southern Kentucky called Bugtussle introduced him to farming, his first ferments, and a wonderful lady. He now runs Rough Draft Farmstead with his wife Hannah in Danville, and you can read their blog and follow their story at roughdraftfarmstead.com. Jesse is also available for speaking engagements and seminars on gardening, starting small farms, and fermentation.

42 Responses to “The Skinny on Fermentation: Un-canning Tomatoes”

  1. Todd Howard
    August 20, 2012 at 7:25 pm #

    Sounds great! I was looking for something unique to do with the glut of tomatoes I have remaining. Do you see any issues in using a 10 gallon crock (its all we have)?

    Thanks,
    Todd

  2. Todd Howard
    August 20, 2012 at 9:23 pm #

    Another question, how exactly does fermented tomatoes seal in the quart jars?

    Thanks,
    Todd

  3. August 21, 2012 at 12:23 pm #

    Hey Todd,

    The 10 gallon crock would work just fine, even if you only do two gallons-worth. As for the sealing, it doesn’t seal. True ferments do not require a sealed container because, in lieu of trying to prevent bacteria from spoiling food, you’re encouraging bacteria to protect it. What I would do, and what has worked really well for me in this case, is fill a mason jar most of the way full and pour a little olive oil over top to keep the oxygen off the ferment. Or, since this recipe bears a lot of similarities to making wine, you could simply pour it into a wine bottle and put a cork in it. The objective is to keep the oxygen off as much as possible as oxygen encourages mold.

    Let me know how it goes and if you have any more questions!

    • Jennifer Bell
      October 20, 2014 at 7:11 pm #

      Hi Todd — I just pulled some tomatoes, mostly green a few red, out of my crock — I used just 5 lbs tomatoes to 3 Tbl salt like a kraut recipe. The tomatoes have a flavor and odor similar to beer and are a little fizzy. The brine tastes like salty beer…not necessarily bad…just strange. It is tangy, like it is supposed to be — but this unusual turn toward alcohol is a new thing for me. I did let it go for several weeks, probably a month — in about 65 degree weather…the first time I opened it, about a week ago — it smelled distinctly of alcohol — today I jarred it up, and it had the bubbly scum on it — probably a yeast. (from what I’ve read scum is a yeast, not a mold) — have you ever had this experience?…

  4. August 21, 2012 at 11:26 pm #

    I would never have thought to do this – wow, so fascinating, and I really love the idea of preserving without canning. Do you know the science behind the odor it gives off? What causes that I wonder? Also, is it more tangy than regular tomato sauce, and do you think it would be good with some basil added to eat with spaghetti? Thanks so much for sharing your knowledge and making the concept accessible!
    -Jaime

  5. August 22, 2012 at 10:20 am #

    Hey Jaime!

    I did try to do some research on the odor, but since few people really ferment tomatoes this way I couldn’t find any info on it. I looked in Ashworth’s “Seed to Seed” because this method is almost identical to saving tomato seed (in fact, if you did all the same heirloom tomato, you could literally just pull the seeds out, dry them, and plant them the next year!), and though she comments on the odor, she doesn’t say what it is. I’m still looking, though! As per the basil, I’m sure it would work but I’m skeptical about adding softer herbs––basil, cilantro––as I’m not convinced the flavor would remain for a long period of time. I added peppers, rosemary and garlic and would also consider trying onions, but herbs like basil I might freeze and add later. The results of this are definitely more “fermenty” and acidic than canning, and I find myself reducing each jar down a little before adding to pastas, but we are loving the flavor! Good luck if you try it and let me know how it goes!

    Best,
    Jesse

  6. Todd Howard
    August 29, 2012 at 9:40 pm #

    Canned the maters on Monday. Boy did we ever mess up the salt needed. We grossly miscalculated the entire volume of our maters, we thought we had 10 gallons (long story on how we arrived at this conclusion), adjusted the recipe to add enough salt for 10 gallons. In reality we only had 4.5 gallons of maters…

    Amazingly the maters turned out alright, with the exception that every bite taste like one of the kids dumped over the salt shaker when no one was looking. We are in the process of ACTUALLY doing another batch and we have correctly measure the quantity of our maters. Expecting better results!

    Thanks for providing this to the world to utilize.

    Todd

  7. August 30, 2012 at 10:19 am #

    Hey Todd,

    Glad to see you gave it a whirl! If you wanted, you could make a batch with very little salt and blend the two. Just a thought so as not to have to waste too many tomatoes. I’ve also heard soaking a raw potato in something too salty will help absorb some of the salt, though I’ve never tried it myself. Let us know how it goes!

    Jesse

  8. Julianna
    August 31, 2012 at 11:11 pm #

    How long will these last? I am getting mixed reviews from the research I have been doing. Some say weeks, others say a year. I am confused!

  9. September 5, 2012 at 12:10 pm #

    Hey Julianna,

    Kept in a cool place, I’m confident these jars could last several months, likely until next year’s tomatoes! I just opened a month-and-a-half-old jar and it literally bubbled out and onto my counter, alive, tasty and perfectly healthy. It’s hard to say for sure, but keep it in a cooler place like you would a wine it should last several months. My last batch shows absolutely no signs of slowing down. Thanks for your comment!

    Jesse

  10. Adam
    October 2, 2012 at 5:57 pm #

    Thanks for the thoroughgoing information! I spent yesterday afternoon sluicing seeds to ferment and save, and tossed all the meaty remains in a pot and hid it in the oven with the intention of making proper canning sauce when I returned home from work. Well, I forgot, and the next morning I pulled it out to find a gently frothing mass! I unnaturally feared I had whipped up botulism soup, but I quickly found your article here and am now on my way to my first batch of fermented tomato sauce. One question: do you think a nonreactive metal pot (stainless steel) would be OK for the initial fermentation?

    • October 3, 2012 at 2:23 pm #

      Hey Adam,

      I love this story, and I don’t foresee any issues with the stainless steel – they do wine in it all the time! Should be fine, and good luck. Let us know how it goes!

  11. October 18, 2012 at 11:45 am #

    Hi Jesse
    I have been experimenting with fermented tomato sauce here in the UK. Most recipes seem to strain the tomatoes to get rid of the seeds and skins, you don’t bother – is it still good? Seems a lot less work so I hope so! Also can you tell me if you heat the sauce have you killed the good bacteria in it? Should we be using this raw like a salsa?
    Many thanks
    Katie

    • October 18, 2012 at 5:31 pm #

      Hey Katie,

      Thanks for the comment! No, I didn’t bother to strain and I suppose you could but I like a chunkier tomato sauce and after fermentation and a little time in the jar the seeds are broken down enough to not be much of a nuisance. As for cooking vs. eating it raw, I would definitely recommend eating raw––in salsa’s or juices––for the most beneficial bacteria because yes, you are killing bacteria by cooking it. But the general thinking is that cooking fermented foods is still going to be considerably better for you than canned, plus, some of the beneficial bacteria might still live, or at least continue to be beneficial. I hope that helps!

      Jesse

      • Al
        October 18, 2012 at 11:21 pm #

        Jesse – I know you recommend using fresh tomatoes, but I just froze up several gallon bags of tomatoes a few weeks ago (did not blanch, just cored and froze). Could I still use these tomatoes for fermenting like you describe, or did the freezing diminish the results I would expect. Thanks – Al

        • October 19, 2012 at 7:36 am #

          Hey Al,

          Thanks for the comment! Although I have never frozen and then fermented tomatoes, I would like to think––so long as they were fresh and healthy tomatoes when you froze them––they would still have plenty of life left in ’em, and would thus be ok for fermenting. Again, though, since I’ve never done it that way I can’t vouch for the results, but I might also say that frozen veggies are often far more nutritious than canned anyway, so you’re already doing it right! Let us know how it goes if you do try and ferment some––would be interesting to hear how it went.

          Best,
          Jesse

  12. Chantel
    February 22, 2013 at 10:44 am #

    When I was in Kiev, Ukraine, the family I stayed with fermented tons of tomatoes from their dacha. They did it with beautiful whole yellow tomatoes. I ate them at every meal. Slightly tangy but not too sour, they were great. Does anyone know how to ferment them whole?

  13. Tina Koyama
    June 9, 2013 at 12:45 am #

    This is great! Thank you so much for this recipe. I’m looking forward to trying this when my tomatoes are harvested this summer! By the way, the the person who asked about fermenting tomatoes whole, I happened to find this recipe (though it uses whey):
    http://www.culturesforhealth.com/lacto-fermented-whole-cherry-tomatoes-recipe

    • June 27, 2013 at 6:05 am #

      Thanks for the comment (and apologies for the delayed response)! I had really great results with this recipe last year, but if you have whey available, I say use a little to inoculate the ferment. I’m going to try a few different tomato ferments this year involving whey and without–look forward to some fun tomato preserving ideas!

      -J

  14. Paul
    August 9, 2013 at 9:58 am #

    Hey, just curious, but besides the obvious taste of “tomato sauce”, how does the fermentation change the taste? Is it more savory? Salty? I know that sauerkraut and kimchi tastes much different than the cabbage they are made from.

    • August 10, 2013 at 3:35 pm #

      The flavor will indeed be much more akin to kraut than tomatoe sauce! It’s a bit more tart and acidic. I have really enjoyed it with salsa’s, juices, or certain sauces. I recommend adding a little sweetness, however, to balance it out for sauces. Start with a small batch and see how you like it!

      Jesse

  15. Lynn
    August 10, 2013 at 6:18 pm #

    On Aug 1st I put 8 lbs of tomatoes, salt and water into a 4 gallon crock, tied on my cloth and waited for the stink. Nothing for the first day. The second day I saw some bubbling and began to smell bourbon whiskey when I stirred. I don’t call that stink but at least I was smelling a change in them. All week I stirred and sniffed waiting for the smell of fresh tomatoes to come over the alcohol but it never completely left. Today, 7 days later, I could wait no longer and jarred them up with olive oil. I tasted them, of course, and I cannot believe how they turned out. They taste like salty pickled tomatoes with a shot of moonshine. I like them! However, I am not sure this is what I was suppose to end up with. Also, I can’t think of any way to cook them except over rice. Any suggestions?

  16. August 21, 2013 at 9:10 pm #

    Thanks so much for the information on the fermented tomatoes,I already have been doing Kim chi and fermented veggies but have never tried tomatoes for the reason of mold.Next I will be trying keifer milk wish me luck.Thanks so much lots of information you have will keep reading.Karen

    • August 24, 2013 at 3:01 pm #

      Good luck, Karen and thank you for reading!

  17. Tatyana
    September 2, 2013 at 2:54 pm #

    Thank you for a great recipe! I placed everything in mason jars today and stashed in the refrigerator. It took about 5 days until I felt the tomatoes were ready.

    It is going to be hard to wait for winter :0)…

    PS
    I just used tomatoes and tons of garlic. The taste is amazing! Can’t wait to try it with vodka :0)

    Cheers,

    Tatyana

    • September 3, 2013 at 12:47 pm #

      Very exciting! Let us know what comes of it all!

      Jesse

  18. Jacqi
    September 10, 2013 at 3:35 pm #

    I’m thinking adding all the ingredients for salsa and then throwing it all in the blender with some fresh cilantro when you take out each jar to eat.

  19. Meghan
    September 18, 2013 at 12:49 am #

    I started these a little over 24 hours ago, but there is no bubbling or smell?

    Should I add some whey to get it going? Anou how long does it take for it to start bubbling and smelling?

    Thanks!

    • September 18, 2013 at 11:58 am #

      Whey never hurts! It should start bubbling any time now, however. Good luck and let us know how it goes!

      Best,
      Jesse

  20. Bryce Steiner
    August 3, 2014 at 2:37 pm #

    It’s been a couple of years now since you did this and I want to follow up.
    I just found your site and I love what you are doing. Could ANY vegetable be fermented like this? This is so similar to making sauerkraut, it makes me think anything could work with the same methods.
    You mention it’s like wine and you could use wine bottles and corks
    If you keep the oxygen off won’t it last many, many years like wine? How long did it end up lasting? How will you know if it has gone bad?
    Unlike wine, you do not add any yeast. Would there be any reason to do that?

  21. Lance
    September 8, 2014 at 10:04 am #

    Hello,

    Let me tell you about my firsthand experience at fermenting vegetables. I ferment everything and love to experiment. I did a pumpkin, sweet red pepper and onion ferment a few years ago and OMG was it delicious. I do salsa and once I pack the vegetables into the jars there is still quite a lot of liquid with small pieces of vegetable. I simply pour these into jars and use as juice. It’s very tasty and refreshing and you can feel the live enzymes coursing through you. I just opened a jar that I made over two years ago and it was perfectly fresh. Not even a trace of mold. I use Fido jars though, and I bought well over a hundred of these from a half-quart to 2.5 gallons in size. These jars are amazing for ferments. Once you close the lid, you never have to open it to release pressure. They are designed to release the Co2 when it builds to a certain pressure and the constant pressure keeps any oxygen from entering. I used to use mason jars and having to unscrew the lids to release the pressure and the worry of exploding glass made me switch to the Fido jars and I’ll never go back. I just made ten jars of sweet peppers with different herb combination such as parsley and dill, mint, dill and garlic, cilantro, and I also added a couple of slices of hot pepper to some. These are great to snack on or put on sandwiches. Then I made a few quarts of pure hot pepper mash to ferment for thirty days and then grind up and strain for hot pepper sauce. I also did some jars of sweet peppers so when I get the strained result of each, I’ll try some combinations to get different flavors. The latest thing I’m trying, which I made yesterday, is a 2.5 gallon jar of whole tomatoes, basil and garlic. Man does that jar look pretty. It’s like a decoration. I’m going to try another with whole tomato, dill and garlic. Then of course cucumbers. Will be doing a bushel of them later today. Of course, the garlic and dill are favorites, but did you ever taste a fermented pickle using dill and fennel? Incredible. I have so much fun giving those to guests and asking them to guess the herb, and no one ever has. It’s just indescribable. It’s a beautiful and complex flavor. I also made kimchi two years ago and still am opening jars that are perfect. I love turnip, daikon radish and ginger kimchi. My inspiration for going far beyond the sauerkraut and dill pickle making that I learned from my father, who learned from his father (Polish background explains that), was Sandor Katz’s ‘Wild Fermentation’ book. It’s a great book to get starting with this fascinating method. One can also find tons of info on the internet.

    Regards,

    Lance

  22. Jessica
    October 10, 2014 at 4:43 pm #

    Hi, I am just about to try fermenting tomatoes for the first time. Some recipes warn the tomatoes will turn to alcohol after a few days and warn to only keep for 1 month in the fridge. Have you had this happen? I plan on storing them in my cold room, which stays just above freezing in the winter.
    Thanks

    • Bryce steiner
      October 20, 2014 at 10:31 pm #

      It won’t be a problem. I have not seen it ever turned to alcohol. So far the one I made the summer has gone about two months and it still tastes fine. I did use olive oil and that sits on top to keep the oxygen away. None of this is been refrigerated. It sits on the top shelf in my kitchen where the temperature varies from hot 80° days to 55 in the morning’s on chilly fall days.

      • Jessica
        October 21, 2014 at 1:15 pm #

        Thanks!

  23. Dar
    November 12, 2014 at 11:02 pm #

    Just opened my month old fermenting tomatoes and mild peppers and asked myself what am going to do with them. My goal was to have a semi fresh tasting tomato in the winter. This website was the answer to the question. A little oil, garlic plus fermented tomatoes on salad greens sounds excellent. My half gallon of fermenting zucchini slices and mild peppers will be sprinkled with dill and served as is or in the salad. My half gallon of fermented garlic is about gone–it is good. But the real exceptional fermentation is fermented peppers—whether jalapenos, or guajillos or probably any hot pepper, I chopped them in a blender and set up fermentation for at least a month. Red peppers have a milder taste and sort of fruitier. Green peppers are really good,too. Some I puree for sauce and some I just leave relish style.; Interestingly no matter how many I eat I haven’t had a lower digestive upset with them. Use to be that over three jalapenos would cramp me big time. We also eat our fermented sauerkraut every day.

  24. Adam
    June 9, 2015 at 7:58 pm #

    Very cool. I imagine this would be a thin sauce and take up more space than a cooked tomato sauce, or does water evaporate with the process? Can you cook down the tomatoes and introduce cultured whey to start the fermentation or is rawness essential?

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