Yeast Washing: A how to

Yeast is the single most expensive ingredient that you will purchase as a homebrewer. Per unit it blows away any other ingredient. Grain is generally $2.50 and under per pound. Hops runs $2.00 and under an ounce. And we don’t really put water into the equation since it’s cheaper than anything else. Yeast on the other hand is usually $6-12 a vial or smack pack depending on the store, variety, and rarity of the yeast stain you buy. Even dry yeast runs around $3.00 a unit. For this reason, many homebrewers like to reuse yeast and thus, bring down the cost per unit of their yeast. But what happens if you want to brew a stout and then a light colored ale? There really isn’t a good way of getting all of the beer and wort separated fully.

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I’ve been trying to make some strides in my homebrewing costs and I stumbled into yeast washing. The idea behind yeast washing is that you take a yeast cake, add water, and then pour the slurry into smaller containers. You then give the slurry time to separate and repeat. The heavy materials (dead yeast, hop particles, etc) will settle to the bottom and the healthy yeast will remain in suspension or layer on top of the heavy materials. You then pour the good stuff into another container and get rid of the heavy materials. Now let’s get into the nitty gritty.

1. Materials

You will need the following things to wash yeast:

  1. A pot to boil water in
  2. Mason jars with sealable tops (about 4 are needed)
  3. Tongs
  4. A funnel

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2. Sanitize

The first thing that you will do is put the mason jars, tops, and tongs into your pot. Add enough water to cover everything. Then boil for 20 minutes or so. The basic idea here is that you are trying to sterilize everything and anything that will touch the yeast. You will also want to soak your funnel in your normal brewing sterilization material. I use iodophor.

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3. Cooling

After you have boiled everything you want to use the tongs to grab the mason jars out of the water and put the tops on. Make sure that the jars have as much water in them as possible and leave as little head room as possible. The place the mason jars with tops in the fridge and allow them to cool. You will be adding the water in the mason jars to your near empty fermenter.

4. Adding Water

Use the funnel to pour water from three of the jars into the fermenter. Place the tops of the mason jars in a safe and sterile environment. I used the same bucket that I soaked my funnel in. You want to have at least one jar full of water for future use. After the water has been added to your yeast cake swirl it around to get the yeast into suspension. Once you have done this use your funnel and place it over your mason jar and fill the mason jar with the yeast slurry. Make sure to fill to the top and then add sanitized tops to mason jars.

5. Settle down now

Allow the yeast to settle out. I put my three mason jars in the fridge for three hours. You will see that the water and yeast separate out.

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6. Combine

After your yeast has had a chance to separate you will want to grab your one remaining jar. Pour out the water. Take each settled mason jar and pour out a bit of the water, you will not need it. Then pour the healthy yeast (it will be a lighter gray color) into the jar that you just poured the water out of. Repeat this process until the jar is full of healthy yeast. Make sure to sanitize the top of the mason jar again and then put it on the newly filled mason jar. Image note: This was taken immediately after filling so it is a bit “dirty.” When it settles you will see clear liquid on the top and yeast on the bottom.

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7. Final Notes

You now have washed yeast. The vast majority of hop, color, and additional unwanted flavors are now out of the yeast. Store the jar in your fridge (I use my emergency beer drawer vegetable drawer). Your yeast will last about 6 months. You can build an amazing collection of yeast style and start your own yeast bank. Make sure you pay attention to sanitation during this process. Any lax sanitation processes will result in the loss of your yeast and/or the contamination of future beer. This is not a hard process and I have had wonderful results. Take your time and pay attention to details.