Jar filled with plums, koji, rice, and shochu

I recently bought some fresh local plums from the farmer’s market, and my mind immediately went to “how do I preserve these?” Nevermind that these plums are delicious, I want to enjoy them not now, but three months from now!

I think my brain is a little broken. But hopefully, dear reader, your mind is something like mine, and you’re interested in playing with your food.

One of the first things I thought of was plum wine, or umeshu. That delicious, sometimes cloying liqueur is generally made with unripe plums, rock sugar, and shochu.* While I do have shochu and some rock sugar, my plums are ripe, but I’m not going to let that stop me!

Then, something else occured to me. The reason that rock sugar is used instead of granulated is so that there is a slow release of sugar into the liquid. This allows the concoction to be sterile from the alcohol in the beginning so that no unwanted fermentation or spoilage occurs.

Isn’t that what’s going on in mirin?

One of the first logbooks I posted (which, as of this writing, is still ongoing) was Mirin, that is, true mirin from koji, rice, and spirits. The shochu (or in my case, Korean soju) prevents fermentation while the enzymes from the koji work on the starches in the added rice to develop sugars and some umami flavors. These sugars are developed over the course of months, so… why not combine the plum wine and mirin process to make plum mirin?

Day 1—9/13

  • 318g ripe plums
  • 300g koji rice
  • 300g steamed rice (weighed after steaming!)
  • 750mL shochu (20% ABV)
  • 2L jar

Combine in a jar and seal—done.

Now, you may notice that the math is, well, a little concerning. I didn’t realize it until I began writing this down, but the weight of all of the ingredients is more than the weight of the shochu. This wouldn’t be a big deal, except the ABV of the shochu is 20%. If we do the math, diluting 750g @20% with 900g @0%, all together we’re now at about 8% (though obviously were now talking about weight, not volume).

However, for the moment at least, the mixture should be sterile as the liquid is basically still 20%. As the rice saccharifies and the plums… do what the plums do, the alcohol will begin to dilute and creep closer to a point that spoilage could occur. I may try to locate another bottle of shochu and just double up the amount of alcohol so that, once equilibrium is reached, we end up at a higher ABV.