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I like reusing yeast to save money, and I like having my own "house" yeast. However sooner or later my yeast eventually dies and becomes unusable. I have a feeling that each time I repitch, I'm getting more an more crap and less and less yeast.

I once read something that either White Labs or Wyeast put out on how to properly clean yeast for reuse, but the page has since been down.

Does anybody have a good method of cleaning the yeast they plan on reusing? Also, what temp do you normally store yeast waiting to be reused?

Currently I just pour most of the beer off the slurry then mix it all up and toss it into some bigger bottles. When it comes time to pitch I dump off the old beer and dump in the old yeast.

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+1 I had never even considered doing this. Cool. –  Poshpaws Jul 1 '11 at 13:30
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2 Answers

up vote 25 down vote accepted

How to Rinse Yeast for Reuse

  1. Collect yeast solids from fermentation.
  2. Place yeast in sanitized (or better yet, sterile) container with water. The water volume should be around 4-5X that of the yeast. A cylindrical, tall container with a screw-on cap works well.
  3. Leave some headspace for air for shaking. Seal the container.
  4. Shake vigorously. Really vigorously: it's not a polaroid picture. Make sure you break up yeast flocs.
  5. Let yeast settle for a few minutes.
    - You should see a first layer form at the bottom: dead cells, brown yeast, and hop matter.
    - A second, thicker, creamier layer will form. This is your viable yeast.
    - A top layer will form more slowly, containing lighter cells and proteins.
  6. Pour the top layer off and discard. Collect the middle layer. Discard bottom layer.

Repeat as needed.

Storing Yeast

  • Store yeast between 33°F and 36°F.
  • Avoid using strong or hoppy beer as a storage medium. Sterile distilled water works well.
  • Try to reuse yeast within 14 days.
  • Outside of two weeks, consider a viability test. Most strains of yeast will lose 50% viability every 4 weeks.
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Should this be two separate questions? –  Brandon Nov 30 '10 at 4:56
    
Wow. Where did you learn this from? –  Jeff Roe Nov 30 '10 at 5:15
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This is how I do it to. I like to use Mason jars because I can boil them for sanitation. And boil the rings and lids. Also the separation is easy to see through the clear glass. –  brewchez Nov 30 '10 at 13:02
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I have heard that you should boil the storage water to drive off any disolved O2 so the yeast will stay dormant during storage. –  Northern Brewer Chris Nov 30 '10 at 16:07
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If you should only store for 14 days, how does the yeast you buy commercially last so long? I can make this a new question if people think I should. –  PMV Nov 30 '10 at 17:17
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Storing yeast in the fridge (i.e. above 0C/32F) is great if you can use the yeast within a few weeks, or a couple of months at the most. Any longer than that, and cells will die and the yeast becomes less viable, Then, a starter is required to step up the cell count to ensure you pitch enough viable cells.

An alternative is storing the yeast in a 25-30% glycerin solution and store it in the freezer. You can store as much or as little as you like, but typically anywhere between 2ml and 20ml. In the freezer, the glycerin solution doesn't freeze, but keeps the yeast very cold, so they go dormant, and can remain that way for years.

I recently took out a 16ml vial, stepped it up to a 500ml starter for 2 days and then again to 2 liters for 3 days. The vial was 3 years old and has made a healthy 2 liter starter.

The advantages of freezing are that you can have a wide selection of yeast available. The yeast stay viable for years. When you reach the last vial or two, you simply make a starter from that and put that starter into vials for freezing. You can propagate the yeast almost indefinitely.

The downside is that you need some extra equipment and have to start preparing the yeast for your brew 3-5 days in advance.

The process for harvesting yeast is simple, but more than I can describe in an answer - and photos so are helpful! Theres a great description with lots of good photos here.

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