Raw Tomato Preserves

This summer I got my hands on a case of fresh roma tomatoes and ventured into this ferment.  I’d wanted to try it for a good while, and when Sandor’s latest book came out, I decided to get to it.  I followed the recipe as is on page 117 of The Art of Fermentation. . I did this in July and with warm temperatures, the ferment went quick.

First I halved the tomatoes, added salt and stirred with my hands.  I did not attempt to get anything submerged at this stage. After 1 day, I could stir it down to where all the halves were submerged.  (I have fermented tomatoes before for the juice [to make bloody marys], and I knew that if I let this go even a day too long the bacteria would strip and  all the pulp from the skins, leaving me only the skins and a thin slurry of what was the pulp at the bottom of the vessel- and this time I wanted the pulp.)

tomato halves readyI stirred two or three times a day.  Each morning a black spidery-looking mold would have formed atop the floating tomato halves.  I would quickly stir this into the mix, and get everything coated in the bubbling liquid. After a couple days, the Kahm yeast would try to get organized in pools of juice around the floating halves, but again, a quick stir would dispel them. Once the rapid bubbling was over, and while there was still pulp on the skins, I strained off what juice there was (about 2 gallons), and processed what remained of the halves, separating the skins/seeds from the pulp. Here are the tomato halves ready to strain.

processed pulpAnd here are the tomatoes being processed in a slick little device I borrowed from the neighbor. Tomatoes in the hopper upper right, paste into the hotel pan on the left. and skins/seeds into the container lower right.




draining juice from the pulpI then put the pulp in a cotton bag and let it hang over night, twisting it to get as much juice out as I could.  At no time did a thick layer of mold appear on the cloth, only a very thin slight white bloom, likely yeast, and I saw no need to attempt to remove it by scraping it with a spoon.


kahm yeast on tomato juice


I put the juice in a vessel, and within a couple hours a lovely rich layer of Kahm yeast had formed.   Since I know this can influence the flavor, I poured the juice into glass jugs with airlocks to keep out the oxygen. I ended up with 2.5 gallons of juice that are now fermenting for next year’s cocktails.



ready to pressNext, I took the ball of paste that had dripped overnight and placed it into a clean cotton cloth and tied the corners. I set this to press inside a stainless steel hotel pan with a concrete block on top, further squeezing out more liquid. I put dry towels beneath and on top of the wrapped ball of paste, and changed these a couple times a day as they wicked out juice from the paste.

salt added


After 3 days I removed the paste and marveled at the color. Gorgeous!  I added salt, 25% by weight, and kneaded it into the paste.  But this proved way too much salt for my palette.  If I use the paste now in a quantity where I obtain the tomato flavor I desire, it is inedible because of the high salt content.  But is it ever beautiful?  Beauty has its limits though, so, frustrated, I formed some of the paste into 1-inch balls and cubes and dehydrated them.  I now use these to grate the dried tomato paste over foods I want to salt, and beauty comes right along with it.  The red color looks spectacular on poached eggs, roasted chicken or steamed cabbage. So, I use it as I would salt, with a little elegance.  The final yield was 1 pint of paste.

completeNext time I’ll use half the salt. (Or I’ll add a batch of unsalted paste to what I’ve already made and see how that goes.)


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26 thoughts on “Raw Tomato Preserves

  1. It’s also a great way to preserve your excess harvest for later use 🙂

    Could you preserve the tomatoes whole or slightly blended instead of separating out the skins and seeds?

    I have loads of tomato vines in the garden, but am currently not allowed to eat them raw as it causes colic in my baby (breastfeeding)… :/

    • Yes, you could ferment them whole or crushed. If whole, you’d need to add sufficient brine to submerge them, and once they split open, the ferment would be very watery (diluted flavor). If your intention is to preserve the integrity of the tomato, either prick or halve them, then salt and let the brine form from their own juice.

  2. Sandor here. I hear what you’re saying about how salty it is, but it also seems shelf stable for months without any molding as a result. Lower salt would definitely taste better, but also be less stable and possibly prone to molding. I think of this intense concentrate as tomato miso. You need only a tiny amount because it exerts such intense and concentrated flavor.

  3. Great post! Reading it, I got a really whacky idea – maybe you could do the same thing with rosehips? Rosehips have been extensively used in sweets and desserts, for a long time, in Sweden, which is my homecountry. However, your tomato preserve contain 25% salt and I don’t see much use of something, with a salinity of 25%, in sweets and desserts. Hence, I’m wondering if you could switch the salt for sugar? They’re both great preservatives, though, of course sugar is very fermentable, unlike salt. However, considering that the preserve would be in solid form and would be kept in a refrigerator maybe the fermentation of the sugar would be so slow that it wouldn’t be noticeable? Or maybe I could just skip salt or sugar and ferment the rosehips alone?

    • You could certainly do the same ferment with rose hips, then you’d need to experiment with how to best use it in the kitchen, since it would probably be unlike other preserved rose hips you’re familiar with. And you could start out with less % of salt. Many desserts here in the US are prepared with an increasing amount of salt, and with specific salts as an ingredient or topping (like smoked salt crystals on chocolate covered caramels).

      I rarely use salt when I cook, and when I do, I nearly always use miso paste (or tekka miso). Even for pie or fruit cobbler, I use a sweet millet miso made with vanilla salt, since it always adds another rich and somewhat savory component which is particularly tasty.

      Sugar and salt can both be used to preserve foods, yet when used in a ferment they attract different communities of organisms, and different flavors. For example: In the absence of oxygen, yeast metabolizes sugar and produces alcohol rather than CO2, and we get wine. If oxygen were present, bacteria would colonize and produce acetic acid. In the presence of salt, the sugars produced by the koji enzymes acting on the carbohydrates from the beans in miso cannot be converted into alcohol, so we get tamari.

      Good luck and let us know how your rose hip experiment turns out.

  4. wow that is a beautiful red color on your tomato sauce and your paste looks divine.. can you also use this for making a home made pizza sauce, i assume you can.. i order both your books tonight, never fermented before, but something tells me i will enjoy food again when i start this fermenting… also i assume i will need a fermenting crock , is this correct? thank you robin

  5. Wow, This is the first time I’ve seen anything close to the ‘coulis de tomate’ that my mother-in-law used to make here in Provence! What you do is exactly what we used to de here. Except to perserve the coulis, we cover the tomato paste in olive oil. If the air can’t get to it, it will last for at least the season and the flavour is just amazing during those winter months when tomatoes are tasteless and sad! Bravo!!

    • 1. See the post on fermented Bloody Mary cocktails.
      2. Anywhere from 1 month to 1 year, or longer.
      3. The only salt added was in the original ferment. (Recipe from Sandor’s latest book.)
      4. I’ve never used whey for fermenting (or for any other reason) so I cannot answer that.

  6. Thank you so much for all the clear answers!! It sounds silly asking about the salt, but I had started this using another recipe and there was no salt added until the end, kneaded in to the pulp.

    Going to the cocktails posts immediately. Sounds delicious.

  7. What was that device you borrowed from your neighbor? I have no idea and wouldn’t try this without knowing how I could separate the pulp.

    thanks. I loved your bloody mary recipe.

  8. Question about the white mold you found in the crock and stirrd back in everyday. I am on day five of the ferment and have seen no mold of any kind. I think I am almost at the stage of straining off the liquid but hesitate. My only thought is that it has been colder than usual this last week (mid 60- low 70) and maybe my ferment is just slow. Is the presence of the white mold nessisarry?

    • I cannot say how low is too low on the salt concentration. The batch I made was too salty, and if I were to make it again, I’d definatly lower the salt. Feel free to give it a try and let me know how it turns out.

    • In my experience, using a lot less salt is fine, so long as you’re going to eat the batch soon. My wife’s father, a cardiologist, maintains that in all culinary matters, using lemon allows one to use less salt. This is especially true in fermentation. The highly acidic lemon juice will pick up the salt’s antimicrobial slack, giving you greater flexibility. Rather than top off my fermented tomatoes with brine, I use lemon juice. It adds a nice fresh aroma and flavor while keeping the saltiness down to pleasant levels.

  9. Question about fermentation time: After 6 days there is still fermentation going on. is this Good or bad? It smells good though.
    Do I leave it untill there is no more bubbling?

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