How much washed yeast to repitch (Slurry,MrMalty)

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demens

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I've read through about 20 threads and listened to a 2 hour podcast on the subject but i still dont have the answer to what i wanted to ask.

I guess to put it simply the question is What is slurry? Or what does MrMalty consider to be slurry?

When you have a jar of washed yeast in the fringe, sitting there for a week, is that slurry? Because it doesn't look that way to me. It looks like a tiny bit of yeast with a bunch of water on top. So if the calc tells you 200ml (based on date) of "Slurry" what is it telling you? And how does that compare to liquid yesat option and making a starter? Lets say i have a 30oz jar, it has about 1oz of Yeast on the bottom.

1. If going off the slurry section. (at room temp) Do i just shake it up again and pour 200ml of it into the new wort?
2. If making a starter...HOW MUCH of the yeast to i use to start with. MrMalty says in vials but i dont know how much a vial holds.

Now lets say i'm making the next batch 3 hours after harvesting. I have my jar of washed yeast. How and how much to a pitch? Do i keep it in the fridge for that time? If i do, i assume it'll settle a bit and separate the yeast thus it wont be slurry, it'll be yeast and water. Do i shake it again to make it slurry and pitch (80ml according to the calc)? Do i need to aerate the wort after doing that since the Yeast was washed with boiled water so it shouldn't have oxygen in it?

At what point should i use a starter? If its been in the fridge for a week, for sure.

What about 2 days in the fridge? Still need a starter?
What about 3 hours?

What if i can't make one? Pitching after 3 hours in the fridge, how long should it take to start fermenting?

What if i dont put it in the fridge just let it settle in room temp for 3 hours, how long till fermentation starts in that case?

Sorry for the ton of questions, i've just been reading so much i came out more confused then i started.


PS
Another thing i'm sort of confused on is how many times you can reuse yeast. If yeast grows in each batch, wouldn't that mean you'd have more and more yeast every time you brew? I've read people say you can get 10 batches off the 1st one depending on how long you keep it, but does that mean you can get another 10 once you harvest it again off the 2nd batch, and 3rd and so on?
 

Pivovar_Koucky

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I think that slurry is all of the trub on the bottom of the carboy after fermentation; yeast, proteins, bits of hops and grain, etc. 200 mL of slurry, in this case would be 200 mL of the trub at the bottom of the fermenter. This is for people who like to rack the next beer onto the previous yeast cake because Jamil thinks that overpitching yeast will harm the flavors of the next beer (specifically, it will reduce ester production, I personally have not yet tasted a beer that I thought would be better if it had more esters).

It sounds like you did a pretty good job washing your yeast. If I was you I would just decant most of the water and pitch the yeast into a 1/2 gallon starter and pitch that into the wort. Personally, I pitch the entire starter at high kraeuzen. I know that a lot of people on the board don't do that.

If you really wanted to, I'm sure that if you pitched your washed yeast directly into the next wort it would come out fine. As for how long it would take to start fermenting, that's something that will vary greatly on a case-by-case basis. How long do you let your beers sit after fermentation is done? What temperature? Do you cold crash? You will probably just have to try it and see what happens.

Another thing i'm sort of confused on is how many times you can reuse yeast. If yeast grows in each batch, wouldn't that mean you'd have more and more yeast every time you brew? I've read people say you can get 10 batches off the 1st one depending on how long you keep it, but does that mean you can get another 10 once you harvest it again off the 2nd batch, and 3rd and so on?

In theory, yes you could do this. I have found that washed yeast tends to get dustier (won't flocculate as well) with the number of times you wash it and the length of time it sits in the fridge (months not days). I only wash lager and koelsch yeast though, for ales I just use dry.

I hope this helps.
 

VTBrewer

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The slurry is the yeast washed form the trub, and settled to the bottom of the vial/mason jar. Estimating the amount of cells in the slurry is a little tricky, but here's a good article that can help you with your pitch rate:

http://www.wyeastlab.com/com-yeast-harvest.cfm

If i'm not brewing again that weekend I make a starter 99.9999% of the time. That being said, i went to pick up a new auto siphon Sunday and came home with a recipe (funny hot that happens) and pitched the below (16oz jar) two week old pacman yeast into a 1.052 stout without a starter. It's at high krausen right now.

pacman_wash.jpg
 
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demens

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I think that slurry is all of the trub on the bottom of the carboy after fermentation; yeast, proteins, bits of hops and grain, etc. 200 mL of slurry, in this case would be 200 mL of the trub at the bottom of the fermenter. This is for people who like to rack the next beer onto the previous yeast cake because Jamil thinks that overpitching yeast will harm the flavors of the next beer (specifically, it will reduce ester production, I personally have not yet tasted a beer that I thought would be better if it had more esters).

I was thinking that too but here is where i get throw off. None of the most important peaces of info in the calculator is the Harvest date. Not sure if its like that for everyone, but for me the default is set to 2 months ago. So it calculates the amount of "slurry" based on the harvest date. And if you harvested 2 months ago, or a month, or a week well then its not slurry anymore the way you describe slurry (and the way i describe it too). Then its just Yeast and water. Sooooo :confused:

On a side note, the yeast that i washed before thats been sitting in the fridge is the one i'll be using for the next batch, the one for the next batch is still doing its thing on the current batch. I'll be brewing my next batch at a different location so thats why i'm assuming that i'll have this new yeast in the fridge anywhere from a few days to a few hours.

PS
I see that you are in New Brunswik, are there any local brew shops in the area?
 
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demens

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The slurry is the yeast washed form the trub, and settled to the bottom of the vial/mason jar. Estimating the amount of cells in the slurry is a little tricky, but here's a good article that can help you with your pitch rate:

http://www.wyeastlab.com/com-yeast-harvest.cfm

If i'm not brewing again that weekend I make a starter 99.9999% of the time. That being said, i went to pick up a new auto siphon Sunday and came home with a recipe (funny hot that happens) and pitched the below (16oz jar) two week old pacman yeast into a 1.052 stout without a starter. It's at high krausen right now.

pacman_wash.jpg

I'll read the article soon but wanted to follow up with a question. So you're saying Slurry is the white stuff at the bottom of the jar in your pic (I though that was pretty much all yeast at this point). If thats the case, you said its 2 weeks old, so you'd need 110ml of "slurry", now its a 16 oz jar, which is about 460ml, from the pic it looks like there is not that much "slurry" in there, i'd guess maybe less the 50ml? So would that mean you under pitched a bit?
 

Pivovar_Koucky

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I see that you are in New Brunswik, are there any local brew shops in the area?

Not super close to me. I usually order online or go to The Brewers Apprentice in Freehold.
 

unionrdr

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Since you sort of have to do a starter anyway,just let them do there thing. They're not just munching,they're multiplying as well. Good to make sure they're refreshed & ready to rock.:rockin:
 
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demens

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Well, i really can't do a stater because i dont have any DME lying around.

I kind of didn't want to order it because i have never done one (this will only be my 3rd batch) and i didn't feel comfortable considering i will be doing a few other new things this time i haven't done either. So i figured repitching some of the washed slurry would keep it simpler.
 
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demens

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Yeah. But how much to i pitch? What is slurry (there are 2 opposing answers in this thread).
 

unionrdr

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The yeast at the bottom,contrary to how it looks,has the consistency of a slurry. And the guy on home brewer TV had about 1" in the bottom of pint jars. Take a pint jar,fill it with the slurry (no water) to about an inch. Make your starter with that amount.
 

VTBrewer

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I may have misspoke on what the slurry is, but the amount of yeast in that jar is usable easily 6 months later in a starter....i know that's not real scientific but the link i posted is. :)
 

Chad

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The slurry is the yeast harvested from the bottom of the fermentor. It contains trub, hop gunk and dead yeast cells in addition to live yeast. That is why the calculator has a slider for non yeast percentage. As the accompanying instructions say,
You slurry contains more than just yeast. There are coagulated proteins, hop bits, dead cells, and other non-yeast solids in the bottom of your cake. Generally, at least 10% of a slurry is non-yeast material, often closer to 15%. If you can see visible non-yeast material, the amount is probably 25%. It is unusual for yeast harvested from a fermenter to have less than 10% of non-yeast material. You can adjust the setting for non-yeast material that you feel is in your slurry by moving this slider. The default is 15% and that is average for most homebrewers.

If, however, you have washed your yeast or even just rinsed it, i.e. mixed the slurry with cool boiled water, let it stratify in the fridge for a couple of minutes to a couple of hours and harvested the middle layer, you have something more viable than a standard slurry. Rinsed yeast will keep in the fridge for up to 2 weeks, according to Chris White at White Labs. The yeast will settle to the bottom in that time so you can even decant some of the water off the top. In that case use the slider for "Yeast Concentration" and move it over into the 3 billion to 4.5 billion cells per ml range. That should get you pretty close.

For reference, a White Labs vial contains 36ml of liquid. When the yeast is packed at the bottom, again according to Chris White, that's a concentration of 8 billion cells per ml. Shake it up and you are looking at 3 billion cells/ml. That should give you a visual reference.

One other thing to note, the "Repitching from Slurry" tab assumes that you are not making a starter, just repitching the harvested yeast.
 
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demens

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The slurry is the yeast harvested from the bottom of the fermentor. It contains trub, hop gunk and dead yeast cells in addition to live yeast. That is why the calculator has a slider for non yeast percentage. As the accompanying instructions say,

If, however, you have washed your yeast or even just rinsed it, i.e. mixed the slurry with cool boiled water, let it stratify in the fridge for a couple of minutes to a couple of hours and harvested the middle layer, you have something more viable than a standard slurry. Rinsed yeast will keep in the fridge for up to 2 weeks, according to Chris White at White Labs. The yeast will settle to the bottom in that time so you can even decant some of the water off the top. In that case use the slider for "Yeast Concentration" and move it over into the 3 billion to 4.5 billion cells per ml range. That should get you pretty close.

For reference, a White Labs vial contains 36ml of liquid. When the yeast is packed at the bottom, again according to Chris White, that's a concentration of 8 billion cells per ml. Shake it up and you are looking at 3 billion cells/ml. That should give you a visual reference.

One other thing to note, the "Repitching from Slurry" tab assumes that you are not making a starter, just repitching the harvested yeast.

Ok, so just wanna go over it again to make sure i got this right.

I wont be making a starter this time, so i'm going with the repitching slurry option.

I will wash/rinse the slurry with cool boiled water. Save a jar in the fridge for 3 hours. Lets say i will have a 16oz (460ml) jar that looks just like the pic in the thread. The yeast on the bottom there is more viable then straight from the slurry, so i adjust the calc to 3billion/ml. If i do this the same day, i just bring the jar to room temp, shake it up and pitch 50ml (according to the calc)? 1/10 of whats in the jar? I'm just re-checking if that makes sense cause it seems like thats very little (but i've never done it before so i dont know).
 

Chad

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Ok, so just wanna go over it again to make sure i got this right.

I wont be making a starter this time, so i'm going with the repitching slurry option.

I will wash/rinse the slurry with cool boiled water. Save a jar in the fridge for 3 hours. Lets say i will have a 16oz (460ml) jar that looks just like the pic in the thread. The yeast on the bottom there is more viable then straight from the slurry, so i adjust the calc to 3billion/ml. If i do this the same day, i just bring the jar to room temp, shake it up and pitch 50ml (according to the calc)? 1/10 of whats in the jar? I'm just re-checking if that makes sense cause it seems like thats very little (but i've never done it before so i dont know).

Almost. Again from the accompanying notes,
When you harvest a yeast slurry and it has settled for a few hours, that is a thin slurry. Usually, most homebrewers will let their yeast settle for a few days in the fridge between one batch and the next. When you do, you'll notice the yeast has settled a bit and is sort of jelly-like. That is the default setting on the calculator.
So if your rinsed yeast settled for several days (and up to 2 weeks) and you decanted the water and just pitched the yeast you would use the Thick Yeast end of the slider. As it is, you have a Thin Slurry, so use that end of the slider.

You are also overthinking this a bit. Since you are harvesting and washing rather than pitching on a yeast cake, there is no danger of over pitching. The larger risk is under pitching. Given that the yeast will only have settled for a couple of hours rather than a couple of days you will still have good yeast in suspension. I wouldn't throw those away. Not only are they viable cells, but discarding them might change the flocculation characteristics of the yeast. I'd shake up the jar and pitch the whole thing or at least a large portion of it.

Just another opinion from an anonymous guy on the Internet.
 

Pivovar_Koucky

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You are also overthinking this a bit. Since you are harvesting and washing rather than pitching on a yeast cake, there is no danger of over pitching. The larger risk is under pitching. Given that the yeast will only have settled for a couple of hours rather than a couple of days you will still have good yeast in suspension. I wouldn't throw those away. Not only are they viable cells, but discarding them might change the flocculation characteristics of the yeast. I'd shake up the jar and pitch the whole thing or at least a large portion of it

I would agree that you are worrying too much about this. Yeast+wort=beer. I think that unless you are an order of magnitude off (10x or 1/10th, for those of you who don't habla)of the pitch rate you will be fine.

If it was me and I had a jar that looked like the picture that VTBrewer posted earlier, I would pour out 75-80% of that liquid, shake the rest up pretty well and pitch that. That being said, I don't think that 1 in 50 people on the forum could reliably tell my beer from a similar beer where you poured the whole jar in.

One more thing, which I might have already said. I have yet to drink a beer that I thought needed more esters in it. So for me the risk of overpitching seems remote.
 

Sarrsipius

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With regard to how long the slurry is viable when you wash yeast...I've read numerous posts from people who wash yeast and use it several MONTHS later. Of course a starter is recomended when using yeast that is this old but many many people have had success with yeasts that has been in the fridge 3 months and beyond. As an earlier poster stated, Mr. Malty will even allow you to account for yeast that is several months old. I wouldn't throw it out after just 2 weeks.
 
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