Lacto-fermented Mustard


Yes, you can ferment mustard. I’m not sure why it isn’t more of a thing. In the same way that Dr. Andrew Weil called vinegar pickles “dead pickles,” (fermented pickles being living pickles, of course), we can say that the normal store-brand mustard is “dead.” Tasty, sure. But from a probiotic perspective, dead.

Fermented mustard doesn’t just offer the usual health benefits of mustard, such as improvements to metabolism and digestion, lowering blood pressure, inhibiting cancer cells’ growth, and more. The fermentation process allows the healthy bacteria present on mustard seeds (as well as the other produce added) to proliferate and enter your gut microbiome, offering additional healthy enzymes and further helping to improve digestion and overall gut health.

Like just about all other ferments, it also adds a distinct flavor.

I’m going to provide a flavorful recipe and give the details for a couple ways I finished it up when blending (one with added lacto-fermented horseradish and one with added honey fermented garlic; these added ingredients are not required for this delicious mustard, just options).

Also, I like my mustard smooth and creamy and therefore added vinegar after fermentation and blended it vigorously. Don’t worry, adding vinegar after a ferment does not actually kill probiotics, though it can reduce the pH to the extent that the probiotic bacteria will no longer reproduce… and it’s worth noting that the bacteria eventually does this to itself over the course of fermentation anyway.

Also, as an alternative to blending to a smooth paste, you could opt for a whole grain or coarsely ground mustard if you prefer those styles. (But then you’d need to separately blend the other components… the garlic, ginger, yellow pepper, etc.)

Shelf life: Like other fermented foods kept in refrigeration, this mustard can potentially last for years. The addition of vinegar at processing will further ensure shelf life.

This recipe yields about two quarts (a half gallon) of mustard.

You will need:


  • 2.5 cups mustard seeds (I typically use 1.25 cups yellow & 1.25 brown; using a 50/50 ratio is popular but more brown will make a hotter mustard)
  • 4 cups filtered or distilled water
  • 2 TBSP additive-free salt
  • 150g pineapple (fresh, canned or frozen)
  • 10-15 cloves garlic (or a full head) (~40g), quartered
  • ~40g ginger, thin-sliced
  • 1/2 large yellow bell pepper, seeded & cored
  • Hot peppers as desired (I added a couple orange habaneros and a bit of ghost pepper; if you want a very spicy mustard I recommend more)

After the ferment:

  • Up to 2 cups white wine vinegar at blending, or to desired taste & consistency (may substitute fully or partly with white vinegar, apple cider vinegar, or other clear/light-colored vinegar).
  • 1 tsp salt per each cup of vinegar
  • To increase mustard heat: 1-2 TBSP of pure ground mustard powder, yellow or brown, at the final blending.
  • For a true spicy mustard: add 1-2 TBSP cayenne powder at the final blending.
  • Optional: consider adding other fermented items at blending; for example, 1/2 cup fermented horseradish or honey fermented garlic
  • Optional: instead of adding those fermented items, for a sweet or honey mustard, you can add sugar or honey (blend in a TBSP at a time to taste). Honey fermented garlic is not very sweet after it has aged but you could also consider mixing it together with fresh honey or other sweetener.


1.) Add all the mustard seeds and prepared produce to the jar, placing the seeds in first. Add increasingly larger components, ending with the pepper half. Use the pepper half as a covering so as to prevent any floaters.

2.) Prepare the brine by mixing the water and salt in a sealed container and shaking it vigorously. (Or combine warm water with salt and allow to cool.)

3.) Once the pepper half is securely holding everything down (and/or using a fermentation weight), gently pour the brine over to prevent dislodging the mustard seeds & pausing periodically to allow time for the water to seep down. Use all the brine and be aware that over the next few days, the mustard seeds will absorb much of the brine and they will swell quite a bit. (The recipe includes enough brine to account for this and still allow for all veggies to be submerged.)

4.) All veggies including the pepper should be submerged. As an added precaution, adding a fermentation weight on top of the pepper is advised. Then apply the fermentation airlock (or use the burp method) and allow at least one month at room temperature to ferment (longer is fine).

5.) At the end of the allotted time, strain out any excess brine (if present) and blend all solids until you reach the desired consistency.

6.) Add up to two cups of white wine vinegar and other additions for the final blending (this will also make the mustard suitable for a squeeze bottle).


For this mustard, I add around 1.75 cups white wine vinegar but it can also be a mix of vinegar and any reserved ferment brine, and blend for 5-10 minutes on high, to achieve the desired consistency. For each cup of liquid added, you can add up to 1 tsp of salt if you want to maintain the level of saltiness. See the ingredients list above for ideas of what to add at blending.

You’re recommended to place and keep the jar in a larger bowl, as the seeds will roughly double in size. Although they’re absorbing brine, you may find that everything in the jar gets pushed upwards, so a glass weight is a good addition if you can fit it. Otherwise, the yellow pepper should be cut large enough to remain firmly in place.

For the batch of mustard featured in this post, I made half with added fermented horseradish (about 1/4 cup), and one with added honey fermented garlic (1/3 cup). Note that these quantities were for half the mustard; you could double the amount (to a 1/2 cup) if it’s to blend into the entire batch of mustard.

Alternately, you could consider dividing into several small variations from your main batch as well. FYI, the featured photo of this post is the horseradish mustard.

I always add the cayenne or other dried hot pepper at the final blending (mentioned in the ingredients section) to round out the flavor.

Let us know (and see!) what you came up with by joining our Facebook group!

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  1. 👌👌 Another must try 😁

  2. Just started mine!

    • Daniel Berke

      Awesome, keep me posted

      • It’s finished! Delicious!! I made it as the recipe said and didn’t add any extra things (just white wine vinegar when blending). Probably the best mustard I’ve ever had. Giving half pints for Christmas presents, and the pint jar is for me 😀 Once I feel like I’m in a good spot to drop some money on more mustard seeds, I think I’ll do it again with dill!

        • Daniel Berke

          This is such an amazing thing to hear. I am so happy to hear it. If you ever get a chance, please leave a review of the site/recipe on the Insane in the Brine FB Page.

  3. How would I reduce this recipe to make a pint size amount without ruining it? It’s only me and I would never finish a half gallon of mustard in a reasonable amount of time 😉 Thanks,

    • If my math is right – and it’s almost never right, so beware – you could just divide everything by four.
      (If there are 2 pints in a quart, and 4 quarts in a gallon, to get HALF a gallon, you’d need 2 quarts, or 4 pints. So to make 1 pint instead of 4, divide everything by 4. Right? Maybe???)

  4. Heather T.

    So good! I only had one cup of yellow so it was 3cups of brown. Just blended it yesterday with one cup ACV and one cup white.

  5. Hi. I just started a batch. I had to divide it between 2 half gallon jars. It’s been put together for one night and the seeds are swelling like the directions said, but they are pushing the other ingredients out of the brine. It is okay to add a little more brine, or will it eventually settle and be okay? This is my first attempt at fermentation so I’m pretty clueless.

    • When you say pushing them out, do you mean they’re rising above the brine, or coming out of the jar? Assuming you mean there’s just things coming above the brine, you really need to get them below. What I’d suggest is putting some (salt)water in a small ziploc and putting it on top, to weigh everything down. A glass weight is much better for sure, but if you don’t have that, this is a quick fix. You want to make sure no water escapes out of the ziploc. You can use saltwater in it if you’re worried the water could escape, it’s still not ideal but better than unsalted water.

      • The mustard seed seems to have absorbed all the liquid, I’ve been pushing it down and weighting it, but the top layer isn’t fully submerged, like there’s not enough liquid. I’m hoping it’s enough, but I think I’m going to have to blend it soon because there’s just not enough juice to cover it. Maybe with the next batch, I’ll add more salt water if it looks like this batch.
        It smells amazing!

        • If the brine has absorbed that fully, you’re likely already at a stage of fermentation where it’s perfectly reasonable & safe to process anyway, especially with the addition of all that vinegar after, there should really be no concern about the pH. Out of curiosity though, how long has it been going?

  6. I’m curious about the peppers and pineapple and their impact on the mustard. Does the pineapple add a weird taste?

    • The pineapple doesn’t add a weird taste at all. This has a pretty traditional mustard flavor I’d say, plus the ferment funkiness, but not really any trace of pineapple flavor. The purpose for these yellow ingredients is to add carbs and bacteria for the ferment to go smoothly, because you can’t count on mustard seeds on their own to ferment. These choices were made because they will also impart a yellow color. The sugars are largely fermented out so it’s not like a sweet pine-apply flavor you end up with. All this said, I’ve made sweet pineapple mustard before that wasn’t fermented and it’s actually really delicious. Imo of course.

  7. This looks amazing! I can’t wait to try it. It’ll be fun to use some garlic and a pepper from my garden.

    Do you think I could halve the recipe, ferment in a quart mason jar and still have room for a glass weight? My wife has patiently endured all my fermenting experiments, but even she might draw the line at half a gallon of mustard! 😂

    • Yes, I’ve done it that way. But I’d go ahead and have the jar resting in a bowl to catch any overflow. I haven’t had this issue myself but a couple others have reported it.

  8. I wonder if you can water bath this after it’s done so it could be sent through the mail as gifts?

    • I’ve sent through the mail without any canning as the ferment process coupled with the vinegar will give this a very low pH and extremely long shelf life. However, yes, you could take the added step of pasteurizing if you wanted to (losing the probiotics in the process but it’s totally your call).

  9. Hi. I made a recipe like this I saw on Facebook: 14 ounces yellow and 14 ounces brown mustard seeds, 6 oz honey, 2 habenero peppers, 4% brine(no amount listed, I ended up putting in 4 cups). It didn’t give any directions after this. How many days do I ferment it? The seeds have soaked up all the brine. Not really any brine above the mix. Do I need to add more brine. This has made one half gallon. Does this recipe seem okay. Also I noticed you didn’t add any honey. Need to know how long to ferment and how will the honey effect it.

    • If the honey was added to the ferment itself, it is another sugar source for fermentation and can ultimately lend itself to the creation of more lactic acid. Not bad but not necessarily the sweet flavor you may have in mind. It also depends how long you let it go. People tend to say this mustard is best after around 70-80 days fermenting, which is what I normally do. I’d go at least a month though. If there’s no visible brine at this point, it could be okay to keep it as is because it may already have hit a low pH and kahm doesn’t tend to grow on mustard seeds like this. How long has it gone already?

      • About 5 days ago. It absorbed all(4cups) the brine and is at the very top of the half gallon jar.

        • Okay, if there’s a weight and you’re able to press down to release brine and re-submerge everything, I would recommend trying that. If no brine will extract, you can safely add more fresh brine, even if it comes to the surface of the jar. How long has the ferment gone so far? That’s worth knowing as well.

          • It has fermented 2 weeks. Should I ferment it 70 to 80 days Or just one month?

          • folks have said they’re favorite results are after 70-80 days. I go at least that long. A month is just to ensure sufficient flavor development. The fact is that pH is not a concern here, with adding all the vinegar at the end.

  10. William J. Lewis

    Does the addition of vinegar stop the fermentation process and kill the probiotics?

    • Vinegar doesn’t kill probiotics in the way people commonly believe. Vinegar further reduces the pH to the point that lacto-bacteria is stressed and goes dormant. In other words, let’s say it was used as a starter for another ferment, where the pH was back to the typical 5-7, it would resume actively functioning. So, the mustard is still technically probiotic (has probiotic benefits) but also won’t pressurize your jar.

  11. Hi Daniel,
    Aside from waiting a month and seeing that my seeds are now 2-3x larger, is there anything else that can indicate it’s done?

    • Checking pH is one way to decide on when to process a ferment. Barring that, a month is ample time to get a favorable pH, or you can opt to wait a couple months more. The best results on this are, in my opinion, waiting 3-4 months, but it’s also not totally necessary. But no, there’s not really anything to look for.

  12. 65 days and today is the day I decided to blend my mustard! The brine is delish and I added:
    12oz white wine vinegar, 1.25 c brine, 2 1/2 tsp salt,1T Aleppo powder, 1T cayenne powder,2 T mustard powder, approx 1/3 cup fermented garlic cloves with honey. My Vita-Mix is wildly unhappy and keeps shutting down from over heating. It is SUPER thick. I have taken out 3/4 of the volume to try to help it blend easier. My question is it seems extremely thick and dry. Is this the right consistency? I was hoping for a little more spreadability

    • I’m glad you like the flavor. It sounds like you need to add more white wine vinegar. Let me know how it goes and if you have follow up questions.

  13. Richard Taromino

    Getting ready to try this. Can you use a pickle pipe for the fermentation lid or better off with a bubbler style? I have both.

    • Pickle pipes only work well under a week, as a broad generalization about this product. The water-based airlock is ideal for a ferment like this which is best done over a few months. Enjoy!

  14. Michael Hauer

    Hi Daniel, thanks for the great webpage, very inspiring. I have made a batch of your fermented mustard and I am about 12 days in. The first week there was lots of carbonation and bubbles, but not so much as of today. Instead I have some cloudy/milky liquid at the bottom of my container. Any chance it has gone bad?

    • Sorry for the delayed reply but you are good. The ferment sounds about done and at this point it is aging. You really almost can’t age this mustard recipe too long, so give it another month or so and process it, I’d say.

  15. Audrie Seluke

    I just finished setting up my half gallon jar and I’m a little bit worried about the seed expansion and the jar overflowing. My pepper “cap” is sitting just below the brine without a weight/ziploc of brine in it. The brine level is a little above the shoulder of the jar. Am I worrying too much? If I need to fix something, how should I go about that without disturbing the seeds in the bottom?

    • I apologize I didn’t see this sooner but brine spillage is not a problem. I would have recommended keeping the whole jar in a bowl. Often what happens is while the seeds expand, they absorb water so there is no eventual spillover the way it seems like there will be. At least, it doesn’t happen to me but I see different setups people make with this recipe and clearly it happens to some folks. Just keeping the airlock clean with a paper towel is sufficient. Did everything work out in the end?


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