Got slurry now what

[cooldood]

OK, I harvested my yeast and have 250 mg jars of slurry in my fridge.
I want to use it for a 5 gallon batch of 1.043 ale.
Can I just get it up to room temp and pitch or do I have to make a mini starter to get it active again?

 

[jmcquesten]

I make starters with my harvested yeast, so I know it's still healthy and ready to go. Better to find out with a starter than a whole batch. I think it's increasingly more important as the yeast gets older. Might not be necessary if you're using it within a week though, provided you have the right amount of yeast.

 

[Yooper]

mrmalty.com has a "slurry pitching" calculator and I use it all the time. I only buy yeast twice per year, so I pitch slurry often. http://www.mrmalty.com/calc/calc.html Click on the "repitching from slurry" tab.

The calculator takes age into account, but if my yeast is pretty fresh, I don't usually make a starter. If it's been in the fridge for a while, I do make a starter.

 

[cooldood]

I have about 25 ml of slurry and the calculator says I need 77. I guess I need to make a starter but how do I calculate what size and how much dme?

 

[unionrdr]

I was thinking the non yeast percentage would refer to the wort?

 

[cooldood]

unionrdr I don't think so but even so I am not sure how that helps me.

 

[Hex23]

I have about 25 ml of slurry and the calculator says I need 77. I guess I need to make a starter but how do I calculate what size and how much dme?

There may be a better way, but ...

The way I do this is to go back to the liquid yeast tab, and change the viability so that the ingoing yeast cell count matches what the "repitch from slurry" tab implies you have. You'll have to do a little math on the numbers reported in the "repitch from slurry" tab. Yeast cells needed divided by mL of yeast needed tells you what it thinks your B-cells per mL is. Then multiply that by your estimate of how many mL you think you have. That is the cell count going into your starter. Then, since all liquid yeast packs have 100B cells, adjusting the viability% is pretty easy. E.g. if you calculated you had 50B cells, setting your viability to 50% works. You can even set the viability above 100% if you need to.

 

[Hex23]

I was thinking the non yeast percentage would refer to the wort?

There are tool-tips that come up when you hover your mouse over those setting. There is a help description here: http://www.mrmalty.com/calc/menu.html

From that help file:

Non-Yeast Percentage:
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.

 

[cooldood]

Thanks for the help Hex

 

[unionrdr]

Dito hex,that clears it up a bit. I used 1/2lb of plain light DME in a 800mL starter before,& was told that was too much. By how long it took the yeast to go through it,I tended to agree. So for 800mL to maybe 1000mL,I'm now thinking 1.4C plain DME. 1/2C tops. About right?

 

[Hex23]

Dito hex,that clears it up a bit. I used 1/2lb of plain light DME in a 800mL starter before,& was told that was too much. By how long it took the yeast to go through it,I tended to agree. So for 800mL to maybe 1000mL,I'm now thinking 1.4C plain DME. 1/2C tops. About right?

yep, that's pretty close. better to be lower gravity than over. 1/2 cup in 1000 mL will yield about 1.031. starters are generally supposed to be between 1.030 and 1.040.