How do you determine how much yeast you have in your mason jars after washing them? I have access to spectroscopy equipment and I could determine this analytically by optical density. But what about the layman? How do you determine how many million / billion cells you have so you do not over / under pitch?
This may give you some idea. From BrewCipher's User Guide, originally derived from reading various sources/estimates... Repitch Slurry Density (Billions cells/ml): If you Repitch Yeast, this is the 'thickness' of the Slurry. It’s used in yeast starter calculations where appropriate. A very thick, compacted slurry would be about 4.5 Billion cells per milliliter. An 'average' density thickness might be 2.4 Billion cells per milliliter. A thin slurry might be 1 Billion cells per Milliliter. Factors that affect density include how long the slurry has been settling (and at what temperature) and the flocculation tendency of the strain. This parameter estimates cells as if the slurry consists only of liquid and yeast. The accompanying parameter (non-yeast %) accounts for the fact that there are other solids in any slurry. This value should be changed by advanced users only. Slurry Solids Non-Yeast %: This is the percentage of your harvested yeast slurry solids that are something other than live yeast (such as hop particles, lipids, dead yeast, etc.). An average recommended value for this parameter is 15 (for 15%). If you rinse your yeast, your value may be closer to 0. If you are pitching directly onto a yeast cake, your value might be closer to 25 or even 50. This percentage is used to reduce the effective cell density specified in the accompanying parameter (Repitch Slurry Density). This parameter should be changed by advanced users only.
I'm not a WLP user, and I haven't used their yeast since they stared going to pouches. I don't know if you can still get your yeast in one of these vials: If you assume that a marble sized glop of healthy yeast is 100B cells from these guys, you can guess about how many B cells you have in a mason jar, right? You could break this down by mL too. The vial is supposedly 35 ml. You're working with maybe 5 ml of yeast per vial. I couldn't find anything written about this and will see if I can find more in Yeast.
Toured the White Labs facility last month. They said the pouches are out in San Diego. The roll out for the rest of the country will take some time. They have an inventory of vials to use up. I haven't been to my LHBS in a while, maybe that roll out has happened.
You didn't ask, but this is a good technical resource for reusing yeast: http://www.brewingscience.com/PDF/BSI_brewers_lab_handbook.pdf Some yeast washing tips that most homebrewers probably aren't doing: For every gallon of yeast, acidify about 100ml of water with a pinch or splash of citric or lactic acid. For every gallon of yeast, add 2ml* sodium chlorite to the acidified water. When concoction turns a very pale yellow (may take a minute), add to the yeast slurry, mixing well. Allow to sit for a minimum of 30 minutes (longer reaction time ensures effectiveness) before using. *Available from BIRKO as DioxyChlor™ at (800) 525-0476 and Five Star as Star-Xene™at (800) 782-7019.
good gouge, but I only reuse yeast that is < 1 week old (and considerably < than 1 gallon)... most homebrewers should not be emulating a lot of specific commercial practices, IMHO doing so, usually leads to problems and/or a waste of time. cheers
Layman don't care about cell count, he keep good track on his harvested yest, make proper starter proportionate to the wort expected gravity. Layman Also use the same yeast and he learn how to good result from it as well as what to expect from it. Personally I do not wash, just collect the yeast avoid the base bottom.
Same here. Yeast washing is unnecessary. I've experimented and repitched yeast both ways and made comparisons of the identically formulated batches, with the only difference being the treatment of the yeast slurry (unwashed versus washed) and after doing this with a number of different styles found that there was absolutely no difference in the yeast performance or the resulting beers. If I were brewing in a commercial setting, I might consider washing the yeast prior to repitching...although I've known commercial brewers who routinely repitched their yeast without the washing step and their beers were always excellent. In my own homebrewing, I have for many years been repitching my house yeast (as well as the one or two commercial strains I sometimes use) through as many as 10 generations without washing and have had dependably good results.
I like to add that the process of yeast washing involve many liquid transfer potently exposing the yeast to unwonted friends
I've read on the interwebs of what you say. I just feel weird trying to define my yeast population by thick slurry vs runny slurry. The scientist in my is screaming "NO! That it NOT how you quantify things"! Not to mention what amount of those cells are viable, and not dead that I am starting with? I guess I could get some conical tubes and put them in there to a similar consistency of the Wyeast & WPL packs, and they would give me a good visual estimate. 10 ml of runny should = 100 billion, and that's pretty easy to scale. But again, what is a thin slurry?
I'm pretty good on aseptic technique, I'm not so worried about contamination. A proper starter isn't just proportionate to expected OG. The volume of wort, age of yeast, etc. all go into play. Also, you can't have a proportion without a cell count. In such a case, it wouldn't be a proportion, it would just a wild guess.
I guess You are Right, I do remind my self that this is hobby very dear one, not a commercial operation. Therefore 100% consistency is not my number one goal. That's can explain way I am willing to aim for quality vs consistency and I can reuse yeast 3 generation spend $7.5 for new pack of yeast.
