How much yeast is too much?

[SmokeyMcBong]

Hey all,

So I have some old vials of yeast here that were donated, I decided that I'd try to grow them up to pitchable. I haven't done any yeast ranching yet and figured this would be a good way to start without risking any expensive yeast. I've already done a 1.5l starter for a couple of days, no stir plate. When it finished, I crashed it and decanted, then added another 2l of starter wort. Its just starting to bubble now.

I was using the yeastcalc site but I put in the wrong production date for the vial of yeast (thought it was older then it was). So after inputting the right production date, the calculator says that I'll need 174b cells for my beer and I will have around 257b cells after this step finishes. Is this too much extra yeast or is it fine to pitch into my beer (I'll crash and decant again first).

Thanks peeps

 

[mkyl428]

Why not just save the extra & build it back up to a pitchable amount for another beer?

 

[SmokeyMcBong]

I could do that but how would I figure out how much to save and how much to pitch? Is there a set number of cells per ml of slurry or something??

 

[mkyl428]

Unfortunately without lab equipment that most home brewers don't have access to it is kind of a guessing/estimation game....

You can use the repitching from slurry tab at mrmalty.com to estimate how many ml of slurry you need

 

[SmokeyMcBong]

thanks bro. I guess that pitching the whole thing would be too much yeast? I have several vials of this same outdated yeast so even though saving some is good practice, its not really necessary.

 

[metanoia]

It's extremely hard for a homebrewer to pitch too much yeast, as in it would have an adverse affect. IIRC, Jamil would always recommend at least a 2L starter for a 5 gallon batch; basically his method is to always step up by a multiplier of 10, and 5 gallons is right around 20 litres.

On the flip side, don't be afraid to save some of those yeasties for later. I had to pull out an emergency reserve of yeast a couple months ago for my hefeweizen when my starter (possibly) got infected, which was about a 60ml jar of slurry in which the yeast has compacted down to probably just under 10ml. While it was a low-gravity beer (about 1.040), those yeast still took off, without a starter, and fermented out to final gravity in 5 days.

 

[mkyl428]

No problem

You would be over pitching, and it may or may not effect your beer, it wouldn't make it taste bad or anything, just different..

I have over pitched a couple times & I didn't really notice much if any difference as a result.

From what I have read it is hard to over pitch enough yeast to dramatically have a negative effect on your beer, at least at a homebrew scale, and I have always heard it is better to over pitch than to under pitch, so you can take that for what it's worth...

If it were me, and I didn't need the extra yeast sitting around I would probably just pitch the majority of the yeast, and not worry too much about getting every last bit out of the flask, maybe leave a couple table spoons of slurry behind & call it good, but I wouldn't worry too much if I pitched all of it either...

Basically RDWHAHB, either way it is going to make a good beer, and no matter what you decide to do with your yeast it will not ruin your beer, just make it different...

Hope that helps

Cheers

 

[rodwha]

I saved my yeast in various repurposed jars so I had no idea how many ml of yeast I was beginning with, but typically between 1/4-1/2" deep. I always made a 1 qt starter with 1/4 lb of DME and called it good.