Yeast immobilization is the weirdest brewing technology I've ever stumbled upon. The idea is to suspend living yeast cells in a semi-permeable solid, producing "beads" with the mystical ability to turn wort into beer. The advantages are obvious: if you start with a few hundred macroscopic spheres rather than a few hundred billion microscopic cells, separating your yeast from your beer becomes very simple. No fermentor goop, no clearing time, no sludge in your finished beer. When you're done, just scoop the beads out, rinse them off, and chuck them in the fridge till next time.
The downsides are also obvious, or at least they seem to be. Immobilized yeast don't actually reproduce. The conventional wisdom would suggest that this should have a significant impact on beer flavor, particularly in yeast-driven styles. Frankly, my hunch is that this is true, and I mostly expect that this experiment will produce sub-par beer. In other words, I anticipate that this will be my one and only attempt at yeast immobilization. But, it's a neat idea, so I thought I'd give it a go.
There are many different viable approaches here, but I'm using sodium alginate. Sodium alginate is an edible salt derived from seaweed. It produces a gooey slime when mixed with water, but that slime turns into a rubbery solid in the presence of calcium. The process is simple and the materials are cheap. Below is the recipe for 100 billion immobilized cells. Scale appropriately to your needs:
* 75 mL of slurry containing 100 billion healthy yeast cells.
* 75 mL of 4% sodium alginate solution (3g sodium alginate)
* 500mL of 1.5% calcium chloride solution (7.5g calcium chloride)
* distilled water (truth be told, I just used tap water and it worked fine, but if your tap water has high mineral content you might consider distilled.)
All of this stuff is cheap. Most people treating their water should already have calcium chloride, and most homebrew shops will sell you more than you ever need for a few bucks. Sodium alginate is a bit more expensive, but $15 of it will last you until the end of time. Amazon sells it in fancy packages for use in "molecular gastronomy" (which is what happens when you let nerds cook).
Steps (see pictures below):
1) Mix the sodium alginate solution well; this takes work. It should be homogenous and similar in appearance to the ectoplasm from Ghostbusters when you're done.
2) Stir in the yeast slurry and homogenize once again.
3) Using a syringe or pipet, drip the horrible goop you have created into your calcium chloride solution, one drop at a time.
4) Let stand for 10-15 minutes to make sure the beads have time to solidify all the way through, then strain them out! Easy as strudel.
I can confirm that the magic yeast beans work, but I can't yet comment on how the beer tastes. I brewed up two small batches and am currently fermenting them side-by-side. I'll post results as I get them in the next post.
Q: Do you know what that stuff looks like?
A: Yes, I know what that stuff looks like.
Alright! Simple experiment here. I brewed up a batch of very basic wort: enough Briess light DME to hit 1.042 (I targeted 1.040, but close enough) and a calculated 15 IBUs worth of galena at 60 minutes. One quart went into each of two large mason jars. I'm using S-04 because it's familiar to most people and also forward enough make yeast character important. Depending on how this experiment goes, I'll consider repeating with a estery belgian something.
* Rehydrated dry yeast
* Pitch rate: conventional (.75 million per mL per degree Plato)
* Approximate cell count: 7.5 billion cells
* Magic beans
* Pitch rate: estimated final cell count after a normal pitch (based on Chris White's growth chart)
* Approximate cell count: 35 billion cells
The worts are fermenting side by side at a temperature of 67ºF. In order to keep things between the two relatively constant, the jars are sitting together in a tub of water. I'll check throughout to make sure that I'm not getting significant temperature differences. Otherwise, it's just wait and see now! I pitched both yeasts side-by-side shortly before midnight last night (12 April), and when I woke up there seemed to be some activity from the experimental but not the control. Right now (1pm), both seem to be active. This is about the only time I've ever wished that I used airlocks! I'll take a gravity reading tonight to see how it's going, and I'll keep the thread updated as I go.
Last night (12 April, midnight):
Today (13 April, 1pm):
Subscribed, and eagerly awaiting the results!
Cool, this should be interesting
Woohoo! Looking forward to hearing the results. Perhaps, instead of waiting to the conclusion of your experiment, you can post intermittently and let us know how it's going.
Please do a control fermentation at the same time if you can.
Incredible! Can't wait to hear how it works!
You have my curiosity. There has got to be a poem that goes with this ;).
Maybe dripping through a course strainer would be way to "rain" the slurry into the calcium chloride. Might be a lot faster than the syringe method.
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