I've been giving this some serious thought seen as though I am mostly brewing small batches (5L). It's a bit of a pinch spending upwards of 7 Euros on liquid yeast for each brew. I've read a few articles and also watched a few vids on the process. Seems pretty straight forward but one thing I'm not clear on is how to determine the cell count / quantity to use on subsequent batches. Any advice would be great. Also, are there any further considerations relative to brewing on such a small scale? Many thanks! Graeme
A good guideline is to estimate 2 Billion cells per ml of washed yeast (this is the solids that settle at the bottom). If you used a graduated container this is pretty easy to measure. Of course this has to be adjusted for time which a decent yeast calculator can do. IMO, a far better method is to make a starter with an excess of cells. Simply pour off and store the excess to use in a starter for the next brew. Fewer steps involved, sanitation is easier, and you ensure the little guys are ready to go to work. Plus, the little yeasties have never gone through the stress of primary fermentation. I typically get 3 - 5 cycles before I buy a new packet and I'm doing 19L batches.
Thanks allot for your response on this. So, if using Mr Malty for example, to adjust for time you would use the harvest date as the production date?
I wash and reuse yeast a lot. I used to really work at just getting the yeast and separating out the trub but now I just try to get 3 pint size mason jars of yeasty-looking stuff. Then I make a starter with the thick part (decant the liquid) from 2 or 3 jars when I am ready to brew. I always make a starter when I brew, but with lagers (even though I step them up twice) I don't think I am ever starting with a big enough pitch because the first batch with a new yeast package I don't get a great ferment but the second or third batch using washed yeast always turn out to be better beers. I rarely brew more than three batches in a row from one yeast as I am always jumping around trying different styles but I do try to at least do two batches in a row from one yeast package. But for really small batches I wouldn't worry at all about having enough yeast--you will from washed yeast.
Yes, that would be a good approximation. Just be aware that if you let the yeast cake sit for 2-3 weeks that may understate the age a touch. BTW, the 2B/ml figure comes somewhat from Wyeast and White Labs notes about their fresh yeast. It is not the gospel but I've found it to be a workable estimate. If you wash poorly and include more trub there is a potential for more error. You didn't ask, but pitching a full pack of yeast in 5L of wort would be an overpitch in many cases. I would let the calc tell me how much to pitch. Plus, I am a big fan of starters for every brew to insure good yeast health.
I'm hoping my second one doesn't arrive broken but this is what i'll be using. Not exact about yeast count but I'm guessing it's like 50-100 ml of clean yeast per 5 gals.
I reuse yeast constantly, no washing. After racking I'll pour off a pint of the yeast slurry into a sanitized flip top beer bottle and use it for a similar beer. Can't help on the cell count but for 5 gallons it works very well
All good points and information, thank you again. I always do a starter on my larger batches but it seems unnecessary at this scale unless I do not have enough viable cells. In the case of my most recent 5L batch, based on the manufacture date I was pretty much on the money to pitch straight in. I would always check in any case and if I had to make a small starter I would
Can’t really know for sure unless you are counting cells under a microscope. I think safest bet is to go with the estimate @PortLargo stated and use until you notice it start to drift or underattenuate. Your risk is low with 1 gallon batches. Would be worth the risk just to experiment with how many generations you can get up to at that assumption pitching rate. Sounds fun, cheers.
Do you make starters from that, or is that your starter? How long do you figure you could keep that refrigerated and still be viable?
I have kept a pint in the fridge for up to 2 months with no problems at all. Usually I reuse on a bi weekly schedule. No starter, just dump it in while the cooled wort is running into the fermenter. # note, be sure to keep the pint of slurry in the fridge until You are going to pour it in. I have had some yeast showers from leaving the bottle out of the fridge after 15 minutes of warming in outside air temps.
