Am I abusing my yeast starters?

[msa8967]

Lately I have been making yeast starters about twice as large as needed and saving 1/2 the yeast to make the next starter. This has gone on to create 6 full size starters from one vial. I know that the pros can do this building up a yeast bank but for a home brewer is there a point where I should just stop harvesting 1/2 the yeast from a large starter?

Could I be abusing the yeast at all in this process? I usually let my starters go on a stir plate for 48 hours and then chill/decant the wort.

My last couple of brew sessions I have done one more sparge where I save this last runnings to make a new starter by boilling it down. I always make sure the gravity does not go below 1.010 (most of the time it is around 1.025 from the excess runnings.)

 

[BigFloyd]

Could I be abusing the yeast at all in this process? I usually let my starters go on a stir plate for 48 hours and then chill/decant the wort.

The only problem I see at a glance is that, going past about 14-16 hours on the stir plate, you're just beating up on the culture and not helping cell count. I watched a video last year made on a tour of White Labs where their cell biologist said that very thing when asked about how long to run stirplate starters.

 

[msa8967]

So do you recommend 14 hours on the stir plate from the initial pitch time or the time when I see activity occur? Can you elaborate on what you meant by "you're just beating up on the culture and not helping cell count"? I want to be able to better explain this to others. Thanks for your reply to my question.

 

[BigFloyd]

So do you recommend 14 hours on the stir plate from the initial pitch time or the time when I see activity occur? Can you elaborate on what you meant by "you're just beating up on the culture and not helping cell count"? I want to be able to better explain this to others. Thanks for your reply to my question.

The "beating up on the culture" were the words that the White Labs guy used and I see his point.

Using a stir plate increases the rate at which the yeast cells can use the starter wort sugar to engage in the aerobic respiration that's associated with their cellular reproduction. When they reach a point at which they've used those sugars up, what does leaving them on the stirplate accomplish?

 

[msa8967]

Thanks for clarifing this for me. I am going to stop at 16 hours and let these rest/chill for the remaining yeast to drop out of suspension. This will shorten my turn around time with this information.

 

[rjmaster19]

I've been looking to do something very similar to reuse yeast.

How big do you make your starters? If you're doing a 5 gal batch, do you just use pitch rates for a 10g?

Do you wash the 2nd half of the starter, or do you just freeze/refrigerate the whole thing?

Any other details you can think of would be much appreciated!

 

[BigFloyd]

I calculate my starters (all done on a stirplate) using this - http://www.brewersfriend.com/yeast-pitch-rate-and-starter-calculator/

 

[msa8967]

If I am to start with a 2L starter for a beer then I will make a 2L split the resulting yeast and use 1/2 of it to make another 2L starter depending on how much yeast I harvested from the first starter.

 

[Scotty_g]

Lately I have been making yeast starters about twice as large as needed and saving 1/2 the yeast to make the next starter. This has gone on to create 6 full size starters from one vial.

For a while I used to extensively re-use yeast but without great washing technique...splitting starters, recovering yeast cakes, letting stuff sit in the fridge, etc. The beer we made with the 4th generation was decidedly less good than the first generation, and we had trouble drying it out. That was when our other brewing techniques were not as good so that may be part of it, but since then I try to limit how often I reculture the yeast. It's enough work to make beer without screwing it up trying to save a few bucks on yeast, so I'm not a big risk-taker there.

I never remember to sparge one last time to make starter wort. Good on you for that!

 

[msa8967]

For a while I used to extensively re-use yeast but without great washing technique...splitting starters, recovering yeast cakes, letting stuff sit in the fridge, etc. The beer we made with the 4th generation was decidedly less good than the first generation, and we had trouble drying it out. That was when our other brewing techniques were not as good so that may be part of it, but since then I try to limit how often I reculture the yeast. It's enough work to make beer without screwing it up trying to save a few bucks on yeast, so I'm not a big risk-taker there.

I never remember to sparge one last time to make starter wort. Good on you for that!

For my brewing I to get as much as is reasonable from my yeast. The closest LHBS is 45 minutes away in the next county. I might wash the yeast for 2-3 generations before starting with a new vial.

 

[rjmaster19]

Thanks for the info, I'm not 100% that washing yeast makes that much sense for less than 2 generations (by the time you pay for DME). But the whole process is interesting enough for me to try it.

 

[kh54s10]

I have seen where the experts from Wyeast and White Labs state that 18-24 hours on a stirplate is enough for reproduction, after that they are just further fermenting the wort with no cell count increase.

I will make a starter that is larger than needed with a new strain. I then make 4 vials with 5 ml yeast, 5 ml glycerin and 10 ml water to freeze. 4 generations is considered optimal so if I made 4 new vials each time I could do 256 brews from the initial purchase.

I sometimes do an extra sparge for starter wort but if the original recipe is not high gravity, the resulting wort would have to be boiled to 1/4 volume or less to get up to about 1.038 -1.040.

 

[msa8967]

Thanks for the info, I'm not 100% that washing yeast makes that much sense for less than 2 generations (by the time you pay for DME). But the whole process is interesting enough for me to try it.

I should have mentioned that I make my own starter wort (and can it) from grain not DME.