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Question about using yeast that was washed from another batc

I made an Oktoberfest a couple of weeks ago and according to BeerSmith, I needed 440 billion yeast cells. I bought 3 packets and then used a starter (without a stir plate) to get what I needed. Since I spent so much money on the yeast, I figured that this is a good time to try washing the yeast.

I have 4 mason jars with a lovely layer of yeast at the bottom. I know that when I want to use it again that I should decant most of the liquid and pour it into another starter. My question is how much of the yeast do I use? Do each of my jars have about the same amount of yeast as 1 smack pack? Do I just use 1 jar or all 4 when I want to brew another beer with the yeast?

thank you

Jon

[quote=“gusrotteyman”]I made an Oktoberfest a couple of weeks ago and according to BeerSmith, I needed 440 billion yeast cells. I bought 3 packets and then used a starter (without a stir plate) to get what I needed. Since I spent so much money on the yeast, I figured that this is a good time to try washing the yeast.

I have 4 mason jars with a lovely layer of yeast at the bottom. I know that when I want to use it again that I should decant most of the liquid and pour it into another starter. My question is how much of the yeast do I use? Do each of my jars have about the same amount of yeast as 1 smack pack? Do I just use 1 jar or all 4 when I want to brew another beer with the yeast?

thank you

Jon[/quote]

Check out www.mrmalty.com . There’s a calculator for slurry thee.

Thank you Denny - that is helpful.

I am looking at the ‘Repitching from Slurry’ tab, and how do I know what to select for ‘Yeast Concentration billion/ml’? It has a slider that goes from 1 (Thin Slurry) to 4.5 (Thick Yeast).

It also has ‘Non-Yeast Percentage’ with a slider from 0 to 25. I assume that this is asking how much of the slurry at the bottom of the jar is the off white color - therefore not yeast. Correct?

Jon

[quote=“gusrotteyman”]Thank you Denny - that is helpful.

I am looking at the ‘Repitching from Slurry’ tab, and how do I know what to select for ‘Yeast Concentration billion/ml’? It has a slider that goes from 1 (Thin Slurry) to 4.5 (Thick Yeast).

It also has ‘Non-Yeast Percentage’ with a slider from 0 to 25. I assume that this is asking how much of the slurry at the bottom of the jar is the off white color - therefore not yeast. Correct?

Jon[/quote]

Correct on both counts. I typically use the most conservative settings. So 1 for concentration and 25% for non-yeast but I don’t rinse my yeast. Just dump the cake into mason jars for reuse.

Rather over pitch than under pitch.

[quote=“gusrotteyman”]Thank you Denny - that is helpful.

I am looking at the ‘Repitching from Slurry’ tab, and how do I know what to select for ‘Yeast Concentration billion/ml’? It has a slider that goes from 1 (Thin Slurry) to 4.5 (Thick Yeast). If the yeast layer is compacted on the bottom, and your liquid is clear and bright above, you can call it thick yeast.

It also has ‘Non-Yeast Percentage’ with a slider from 0 to 25. I assume that this is asking how much of the slurry at the bottom of the jar is the off white color - therefore not yeast. Correct? That is correct. The white layer is pretty much all yeast. The remainder, break material and hop debris, does contain some yeast also. Mrmalty may take this into account.

Jon[/quote]

I don’t consider any of my harvested yeast being 4.5 billion cells per milliliter. I will go more middle of the road if the yeast component looks very clean. As every day goes by the yeast will compact more and more. I have seen compaction up to 100ml over a period of months after the beer on top of the yeast became clear, that is no suspended yeast remaining. Each yeast will be different as to how it compacts and even the size of the yeast cells will make a difference also as to how many per ml.

Viability of the yeast also comes into play. Yeast begins losing viability each day after the production date. In the case of rinsed yeast, the day active fermentation ended, or there abouts.

I always error on the side of over pitching rather than under pitching. Under pitching will affect the fermentation and resulting flavor of your beer. Over pitching, which is hard to do, has very little chance of being detrimental to the resulting beer.

Just curious what the OG of that octoberfest was. Three packages of dry yeast in a starter sounds like a lot of yeast.

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