Simplifying yeast measurements

[markcurling]

Hi all,

I am just starting to reach the stage in my brewing career of using yeast starters/washing/re-using etc. There are lots of threads about pitching the correct amount of yeast without over or under-pitching. Most of these threads rather sensibly refer to the yeast cell count as the key factor in pitching correctly. However, in the absence of sufficient patience to count out several billion individual cells for each brew, the following question popped to mind.

If you have a healthy yeast starter, which is allowed to flocculate before pitching, there presumably must be a more-or-less direct correlation between the cell count and the amount of white yeasty sludge? Consequently, can you simply measure out yeast by the volume of white sediment? Would it be ball-park reasonable to say that you can pitch 40 litres of wort with [X] tablespoons of yeast sludge?

I have a Wyeast propagator pack which I intend to use in a few days. I would like to make a starter and then set some of the yeast aside to keep for future brews, but I don’t really have a feel for how much yeast (in real visible terms) I need to use in the pitch.

Thanks for any tips!

Mark

 

[dcp27]

http://www.mrmalty.com/calc/calc.html - gives you in mL

 

[markcurling]

Thanks, that is a useful calculator, but I am still interested in the original question.

That calculator estimates yeast cell count based on growth limited by sugar consumption.
I am interested in yeast cell count by yeast sediment volume.

 

[JohnMc]

http://www.wyeastlab.com/com-yeast-harvest.cfm
about half-way down might be what you're after.

 

[markcurling]

Perfect!

Around 100g or 5 tablespoons of yeasty sludge for a healthy 23 litre brew, feels about right, we'll see how that goes!

 

[hoppysailor]

We have been blessed by being able to go to a local brewery and get jars of yeast slurry. I tried to make sense out of Mr. Malty's yeast pitching calculator. It can be set for slurry but gives the output in volume. The problem I had was that the yeast would be one volume when I got it and a much smaller volume after settling over a few days. What I decided to do is to pitch by weight. Wyeast recommends pitching 2.2 pounds of slurry for ales up to 1.064 OG. So, what I did is developed a spreadsheet that combines MR. Malty's cell count recommendations with that of Wyeast and gives the weight of yeast to pitch. Probably not perfect but it's provided fast fermentation starts and some good beer. I wasn't able to figure out how to attach the file so send me a PM if you want the spreadsheet.

 

[a10t2]

100 g or 5 tbsp (~150 mL) is quite a bit. I've found that after just a few days in the fridge slurries will compact to about 3-4 billion cells per mL. If the slurry is less than a couple weeks old you could probably just use 3.5 and call it good; beyond that I estimate viability loss at 25%/month.

For an average-gravity 23 L batch that works out to ~70 mL of slurry, or 2.5 tbsp.

 

[JohnMc]

a10t2, a tbsp is little less than 15 ml. 70/15 = 4.6667.

 

[a10t2]

Oops, I was thinking 30 mL for some reason. Stupid non-metric units...

75 mL of packed slurry weighs about 80 g though.

 

[JohnMc]

Oops, I was thinking 30 mL for some reason. Stupid non-metric units...

That's about the volume of a shot. Coincidence?