using harvested yeast

[mtsoxfan]

I just recieved my new stir bar and want to put it to use. I have a harvested yeast that is at least 6 months old. There is about 8 ozs. of compacted slurry. For a garvity brew of about 1.05-1.06, 2.5 gals, and knowing the yeast count is probably low, how much should I use in the starter? If I use it all, as I suspect, will pitching the whole starter, old dead yeast and all, have any negative affect on the beer? I'm talking something notably negative.

[Beer-lord]

According to yeastcalc, your yeast is only about 22% viable and for a 1.060, 2.5 gallon beer, you'll need 104 billion yeast cells and a 2 liter starter wort of 1.037 will get you 137 billion which is more than you need. I would think about 2 vials worth of slurry will do but as old as it is, you might want to use it all anyway. The dead yeast should fall out.

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[mtsoxfan]

Thanks BL. For future referance, how much is a vial in ozs? When you say dead yeast drop out, are you talking about in the starter, they fall like trub, and I would pour only liquid as pitching yeast?

[Beer-lord]

My label says 35 ml. So a bit more than 1 oz I believe. Most liquid yeast is said to contain 100 billion cells but they're fresh. Since you're using old yeast, you are making new yeast cells and you may need more yeast than what's in a 35ml vial. All the yeast I harvest and put into vials I make starters with. I've never used a harvested yeast vial in a 5-6 gallon beer but you likely could if it's just a few weeks old in a 2.5 gallon batch.

Dead yeast won't hurt your beer unless you let the beer sit on it a long time. The 14-21 days you ferment should cause no problems unless you go to the higher temp extremes.
The best option (that I rarely use) is to let the yeast cold crash in a jar for 2-3 days then get a baster and remove only the top, whitest, creamiest layer. That is the best yeast. However, to me, that's work. I just pitch it all in. I keg/bottle my beers between 18-21 days as I usually reach FG in the first 12 days or so. I've left beer on yeast for as long as 4 weeks with no problems.

Others who have more experience then me can chime in but 75% of my beer is fermented using starter yeast or harvested yeast and I'm not looking back.

[mtsoxfan]

Thanks. Do you match yeast to style, or yeast is yeast?

I'm also having issues with my DIY stirpalte... Inkleg said I might. All the stir bar does is bounce... maybe the growler bottom is too thick... I'm using a hard drive magnet, I tried two sizes, same results... Doubling them up doesn't work, as it throws them. I may try to glue to spinning shaft.

[Beer-lord]

I match yeast to style as close as possible. Since I really can't lager, I don't use lager yeast. I've used 1007 German Ale for pilsners and in my Faux RyePL.
I find with my 2 L flask that I have to manually move the stir bar to the center or near center, then carefully place the flask on the stir plate and slowly turn it on. On mine, if I get past half it throws it off so I keep it at about 40% speed and once its going and giving me a whirlpool, I'm good.
Actually, I've read that even if you don't see a whirlpool but the bar is moving, you're fine. After about 12 hours or so I usually see the yeast moving to the top and I know I'm good.

I have a 1L and 2L flask and rarely use the 1L anymore but I have good ones that aren't brittle. I use it on the stove and add a drop of Fermcap so I get no boil over and it goes from boiling on the stove to the sink to chill to the stirplate......no extra mess to clean.

[mtsoxfan]

One problem solved... the throwing of the stir bar...
I made a DIY stir plate, cost $7 and that was for stir bar.
Used a spinning motor, plywood box, old power cord, and now, a used dimmer switch.

My issue was, it was spinning too fast! I thought it might be too slow. When I added the dimmer switch, although I have poor control, off, really slow, a bit more than really slow, then full on. I started at really slow. It was barely moving, but it was moving. Once it stabalized, I increased a bit, and 5 minutes later, I have a vortex!!! The adjustment is too sensative for me to mess with, so I'll let it ride. would like to decrease a hair, but that is not possible. The dimmer just wasn't made for this application, but it works well enough for now...

I thought of an analogy... when we were kids, swimming in a round pool, it was tough to start a whirlpool by all walking in the same direction. Eventually, once the mass got going, it was easier. just needed patience and let the stir plate do it's thing.

[mtsoxfan]

What will it look like when the yeast is active? With the vortex, I do see suspended yeast moving, but don't know what it will look like when it is reproducing. Right now, I have a 1/4" thick foam ring around the edge, but that's it. I know it is too early for anything to be happening, since it is old yeast, likely low amount of viable, and just about 20 hours since pitched. I'm trying to keep below 70*, by having an ice pack lean against it. Using a infrared therm. as inacurrate as it maybe on a shiney bottle, shows anywhere from 66* - 72*...

[Beer-lord]

What you're seeing is what I usually see. And it should look somewhat milky, though not always. You will see yeast going from the bottom to the top and though it's not always the case, mostly, you'll see some krausen form. Many times I have 2" or more of krausen at the top.
Sounds like you got it working ok.

[philm00x]

I don't recall where I came across the information, but the average cell count for washed yeast is 2.4 billion cells per mL of slurry. At this rate, you're at 236 billion cells, but then factor in the 22% viability... 236 billion x 0.22 = approx 52 billion cells. Use the yeast calc to make a starter that will double your viable count to 104 billion cells accordingly from this point.

[ScrewyBrewer]

When in doubt with an old yeast cell count I make a series of step up starters. Its easy put a vial worth of older yeast into a 2 liter 1.030 wort and let it spin for 3 days. Cold crash and decant then put the settled yeast into another 2 liter starter of 1.040 wort and this time you should get a nice thick head of krausen, and pretty close to 150 billion cells. Anyhow its been months since I've tinkered with liquid yeast but I do remember doing something like this to revive yeast that hadn't been used for brewing in at least 6 months and it worked.

[mtsoxfan]

Thanks Screwy, I'll remember that one. I am using a stir plate for the first time...WOW...
Had 8 oz of slurry in 1.045 wort spinning 40 hours, nice vortex... no action. I turned off stirpalte since I wasn't going to be home, and 9 hours later, krausen making a mess big time. I kept it in a small bucket just for that reason. Watc\hing it now, it looks like a heavily carbed champagne releasing bubbles. Very cool looking. I've made starters before with the walk by method, doesn't compare. I'll be pitching later on...

[ScrewyBrewer]

Using a stirplate is the only way to go as far as I'm concerned, in fact I have 2 of them still in storage. I plan to wash some Nottingham this weekend when I package an IPA we brewed and getting the stirplates out of storage soon. Next time you might want to consider using a few ounces less slurry, to keep the krausen inside the flask. But other than that welcome to the world of stirplates, I'm sure you're gonna love them.

[mtsoxfan]

I went with the 8 ozs. because of the age. I'm on a Nottingham kick right now. My 3rd generation went all nutzy on me, so I'll be feeding it to the garden. When washing, it started out light on the bottom. then it formed irregular shaped balls and was distributed throughout. It looked weird, so I decided against keeping.
I'm using a fresh batch in one of my fermenters now, I think I will start being more serious about harvesting etc. keeping smaller quantities and stir plating when needed.