My Microbial Companion: Nukazuke

Assignment:

Start a microbial culture that you will keep as a companion for the rest of the semester.

Idea:

Nukazuke are Japanese rice-bran ferments. They’re made by first preparing a bed of rice bran, salt, water and additional ingredients like mustard powder, kombu, dried red chili flakes and garlic. Other add-ons can be used instead of these. After mixing together the ingredients, bury a vegetable, chopped if necessary but with skin-on, in the rice bran bed. The salt in the rice bran bed functions just like salt in a lacto-ferment; it promotes healthy lactobacilus growth and inhibits other pathogenic bacteria that can’t survive in higher-salt concentrations. The rice bran supplies sugar for the naturally occurring bacteria in the air, and the buried vegetable (especially its skin) often carries a lactobacilus biome that will help begin culturing the rice bran bed.

Each day until mature, swap out the vegetable in the bed. This helps promote a more diverse microbiome in the rice bran bed. I’ve been tasting the pickles each of the last two days; they are noticeably transformed from their normal state, slightly sweeter and saltier, but still very young for a nukazuke. I expect that within a week I will have a mature bed.

Once the bed is mature, I’ll be burying vegetables or ~12 hours or more to get the fermented final product. I’ll try different vegetables, and eventually I may take some of the mature culture to

I followed this recipe, and also learned a lot from The Art of Fermentation by Sandor Katz.

Coconut Goblet of 🔥

This week’s assignment was to fasten at least two different materials together, not including plywood or acrylic.

As I brainstormed ideas early in the week, I kept returning to food. I want food-as-a-medium to be a central theme in a number of projects during my time at ITP. This time around, I was considering making something like a rack to hold mason jars full of fermentations. I was considering making something that made it easy to slide on cheesecloth over the neck openings in the early days of the fermentation, then easily replace the cloth with the regular mason jar lids, with the potential to put sensors and wires into the jars as well (something I’d like to do with PComp eventually.) So— this would be making something to hold something that treated food as a medium.

As I was working through design ideas, I quickly switched gears to go back to using food as a central medium in the piece itself. I decided to use a coconut shell — which I thought would have similar properties to a soft wood, but still present unique learning opportunities for this week’s assignment.

What could I do with the shell? With its natural curvature, it lends itself well to being a bowl or cup. Instead of going far afield, I decided to make a cup. I just broke one of mine, so I’m in the market for another :)

The main design constraint I gave myself here: I wanted to be able to unscrew/detach the coconut bowl from the stem for easy cleaning.

Behold: the Coconut Goblet of 🔥:

public.jpeg

So, did this meet the assignment criteria? Yep— this had a few different materials and fasteners:

  • Coconut to metal

    • I used the “tool of the week,” the tap and die, to thread a metal rod, which I used as the stem of the glass. The thread feeds into a hole in the base of the coconut, atop which I screwed on a 1/4-28 in threaded metal cap. It doesn’t fit perfectly snug, which thwarted my plan for the cap to close off the hole from any liquid.

  • Rope to metal

    • I wrapped the stem of the wineglass in rope, which I sealed with a knot on the bottom end and some hot glue on the top end. Shoutout to Noah for the rope and the hotglue idea, which he used in his project.

  • Coconut and metal to concrete

    • I used a sliced piece of the coconut shell for the base of the glass. I needed to seal off once side of the coconut in order to attach the stem; after considering using laser-cut acrylic, I decided to go a different route and pour in quick-mix concrete. Shoutout to Jake for the idea and pointers along the way.

    • The concrete took about 5 minutes to harden and fit the mold nicely without getting stuck to the tape that I used to keep everything contained inside the coconut. I used a helping-hand tool to keep the stem in place while the concrete set, and it came out straight.

Although I think this goblet is kinda fun, and something I could potentially bust out during a tiki-themed cocktail party, it isn’t quite functional yet. A bit of liquid still leaks through the hole in the coconut cup. I tried to seal off the bottom with hot glue; it’s an incremental improvement over nothing, but it doesn’t eliminate all leakage. A different kind of sealer might work better, but if I want to be able to unscrew the top of the glass for easy cleaning, I would need to avoid sealers that would keep the cup permanently attached to the stem.

I might be willing to bend on that design constraint just so I can drink a banana justino cocktail out of it.

Coconut base taped up and ready to receive concrete

Coconut base taped up and ready to receive concrete

Testing out how the quick concrete would set

Using the tap and die to create threading in metal rod

Finishing the coconut goblet with rope around the stem