Experiment: Fermenting Plums

I normally wait for an experiment to finish before sharing it but have decided to share this one early for two reasons:

  1. By the time it completes it will be too late for others to try it and people may want to try it first.
  2. There is very little written online about it (that I have found) so I thought it would be a good chance to bounce it off the community and see if others have tried it.

Experiment: Fermenting Plums Plum
This recipe was inspired by the Japanese practice of fermenting ume boshi.  I understand that they start with young plums that aren’t ripe and ferment them for a few days before sun drying them and then fermenting them again.  The dehydration is an important step as it allows the plums to become firm so that the continued fermentation (which can last up to a year) will not make them fall apart.

Drying them in the sun (or a dehydrator with a variable temperature control) is important to keep the enzymes in the fruit alive (which will help with fermenting).  There is a lot of debate and misinformation around the specific temperature that these enzymes are killed (there is a great article about that here).  I plan to dry these at 105 degrees food temperature (that’s the measure on the gauge of my Excalibur dehydrator) which means the unit may raise up to 125 degrees air temperature.  Most ovens won’t go under 200 degrees (and many circular units only have a single setting) so using the dehydrator is a big advantage here (we wrote an article on the considerations to make while buying a dehydrator and later followed it up with more considerations on buying a dehydrator).

Ume Boshi results in 2 products: the plums and the vinegar.  Because I am using plums that are riper than called for, my main goal is to produce a salty brine to add umami to my cooking later in the winter.  I’ll report back once I have the final results – in the meantime I’d love to know if you’ve experimented with this type of technique.  I have no idea how it will work out!

Fermented Plums – Ingredients

  • 2 cups (1 pint) plums.
  • 3 tablespoons salt
  • 1 quart (liter) of unchlorinated water (you will use less)

Fermented Plums – Instructions

  1. Pit the plums (a 30-second tip on how to pit peaches or plums)
  2. Toss plums with salt in a large mason jar.  Cover to keep out flies (my favorite tool for protecting fermentations from flies)
  3. Sit on counter for 24 hours.  Toss gently 4-5 times through the day.  This will start the release of liquids and start the brine.
  4. Top with water; weigh the fruit so that it’s under the surface (using a small mason jar inside a larger wide-mouthed one is an easy fix for this).  Cover to prevent flies.
  5. Check the texture of the fruit daily.  When it feels delicate (it will soften each day it ferments and this will happen fast if it’s very hot out), remove from the brine (reserving the liquid) and dehydrate at 105 degrees until firm (4-8 hours).  This could take a few days through a few weeks.
  6. Place dried fruit back in brine, cover with an airlock and ferment for several months (I’m not sure how long yet – like I said, it’s an experiment!)

I’ll update once complete.  Have you tried anything like it?  Will you play along?

 

Comments

  1. MaryAlice says:

    Wild plums grow all around us and are the size of very large cherries, perhaps. I pick them just when they have turned pink, but are still hard. I put them into a large jar, layered with salt. There they sit “for a turn of the moon”. I then carefully remove them each day and put them out to dry in the sun, then return them to their juice each night, for seven days. At the end of that time I have fake ume boshi and ume vinegar. The vinegar, by the way, is especially good on fresh corn cobs. I devised this method when I read the “family story” on a bottle of very expensive ume vinegar some time back.

    • MaryAlice,

      thank you so much for trying. I will one day do exactly this because of you and can’t wait to try – but will have to wait till next year to get them less than ripe. :)

      Joel

  2. I have many friends in Japan, one of whom just posted a series of pictures about making ume boshi. If you have any specific questions, I can ask her. I’ve never tried because my understanding is that the type of plum is critical.

    • Awesome Rachel!

      There’s also a neat note below from MaryAlice who has done a similar process here using plums. I don’t have specific questions – yet – but when I do I will totally reach out! :) Thanks!

      J

  3. Marina Queirolo says:

    Hi Joel. I have some plums in my fridge I will start this fun project tomorrow. How is your experiment going?

  4. Janet Buchanan says:

    Joel, I too would like to just give this a try, though with plums I happen to have (late in the season). I’m confused by your instructions for dehydrating. 4-8 hours vs could take a few days through a few weeks. Are you actually doing as MaryAlice proposes and taking them in and out of the brine?

  5. Just planted a couple of plum trees to go along with the one lonely not-self-pollinating plum I inherited with my property and it jogged my memory. How is this experiment going?

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