This is the procedure i follow when washing yeast from a previous batch, and then preparing it for storage in the freezer.
I have had very good results so far:
1. Sanitize a 2 liter container(this will hold the washed yeast overnight)
2. Boil 2 liters of water, put it in the above container and let it cool to 20C in the fridge(takes 2-3 hours)
3. Rack the homebrew into the keg, leaving the yeast with the trub into the fermenter
4. Add the cooled water into the fermenter, close the lid and swirl
5. Let the fermenter sit for 15-20 minutes. At this time you will be able to see the trub setling in the bottom, leaving the yeast in suspension on the top layer.
6. Carefully pour the top layer of water + yeast into your sanitised container(previously holding the cooled water), leaving the trub behind
8. Put the washed yeast into the fridge and let it sit there overnight for the yeast to settle at the bottom
9. You now have your washed yeast. Discard the top layer of water and store your yeast
You can keep your yeast in the fridge for 1-2 weeks, at which time you will have to use it.
If you are interested in storing your washed yeast in the freezer for long term usage, follow the below procedure:
1. Sanitize a container with which you can measure the volume of your washed yeast(such us your yeast starter flask) and another container that can hold the same volume
2. Tranfer you washed yeast to the above container to measure it. In my case my washed yeast was 250m. At this point i transfer the yeast to my other sanitised container, so i can use this container that is marked to prepare the glycerin solution
3. Plepare a 20 percent glycerin solution with the same volume as the washed yeast(250ml). Since the store bought glycerin is 99,5 percent, you will have to mix 4 parts of water with 1 part of glycerin. In my case this was 200 ml water with 50 ml glycerin, since my washed yeast was 250ml.
4. Mix this solution with the yeast and swirl for the glycerin to dissolve well into the yeast
5. For the next part i use sanitized 50 ml plastic containers, bought from the drug store. If you have other plastic containers that can hold similar quantity, sanitize them to use them
6. Slowly pour the yeast+glycerin solution in the 50 ml containers(10 plastic 50ml containers in my case)
7. Close the lids, mark the yeast and the date, and put the containers in a plastic container or cooler.
8. To prevent the yeast cells from freezing you can put isopropyl alchohol in your large container, or some gel packs. This will also help avoid thawing during frost free cycles.
9. Mr Malty says that thick washed yeast(only solids) contains 4 billion cells per ml. Since each of our 50ml containers has 25ml of thick yeast(before diluted with 25ml glycering solution), this is approximately 100 billion cells. When i take the yeast out of the freezer to make a starter, i calculate that is has 3 billion cells per ml, totaling in 75billion cells, just to be sure. I then create my starter using this calculation.</p>
I have had very good results so far:
1. Sanitize a 2 liter container(this will hold the washed yeast overnight)
2. Boil 2 liters of water, put it in the above container and let it cool to 20C in the fridge(takes 2-3 hours)
3. Rack the homebrew into the keg, leaving the yeast with the trub into the fermenter
4. Add the cooled water into the fermenter, close the lid and swirl
5. Let the fermenter sit for 15-20 minutes. At this time you will be able to see the trub setling in the bottom, leaving the yeast in suspension on the top layer.
6. Carefully pour the top layer of water + yeast into your sanitised container(previously holding the cooled water), leaving the trub behind
8. Put the washed yeast into the fridge and let it sit there overnight for the yeast to settle at the bottom
9. You now have your washed yeast. Discard the top layer of water and store your yeast
You can keep your yeast in the fridge for 1-2 weeks, at which time you will have to use it.
If you are interested in storing your washed yeast in the freezer for long term usage, follow the below procedure:
1. Sanitize a container with which you can measure the volume of your washed yeast(such us your yeast starter flask) and another container that can hold the same volume
2. Tranfer you washed yeast to the above container to measure it. In my case my washed yeast was 250m. At this point i transfer the yeast to my other sanitised container, so i can use this container that is marked to prepare the glycerin solution
3. Plepare a 20 percent glycerin solution with the same volume as the washed yeast(250ml). Since the store bought glycerin is 99,5 percent, you will have to mix 4 parts of water with 1 part of glycerin. In my case this was 200 ml water with 50 ml glycerin, since my washed yeast was 250ml.
4. Mix this solution with the yeast and swirl for the glycerin to dissolve well into the yeast
5. For the next part i use sanitized 50 ml plastic containers, bought from the drug store. If you have other plastic containers that can hold similar quantity, sanitize them to use them
6. Slowly pour the yeast+glycerin solution in the 50 ml containers(10 plastic 50ml containers in my case)
7. Close the lids, mark the yeast and the date, and put the containers in a plastic container or cooler.
8. To prevent the yeast cells from freezing you can put isopropyl alchohol in your large container, or some gel packs. This will also help avoid thawing during frost free cycles.
9. Mr Malty says that thick washed yeast(only solids) contains 4 billion cells per ml. Since each of our 50ml containers has 25ml of thick yeast(before diluted with 25ml glycering solution), this is approximately 100 billion cells. When i take the yeast out of the freezer to make a starter, i calculate that is has 3 billion cells per ml, totaling in 75billion cells, just to be sure. I then create my starter using this calculation.</p>