Questions on Splitting a Starter

[BeerMeUp]

I recently started to wash yeast and also recently began to make starters. Washing yeast isn't a complete pain in the butt, but it can be time consuming and can only be done a debatable amount of times to a strain of yeast. Chatting away at lunch today with one of my brew buddies I came up with some ideas and wanted to see what folks think...

Instead of washing yeast after it fully ferments my beer, could I just take about 8 ounces off of my liter starter and stick that in the fridge to save for next time? I would then use this yeast to build another starter.

Assuming that this is doable, would this count as the same generation as what was used to create the starter or increase the yeasts generation? Maybe it's a half generation?

 

[broadbill]

You can certainly do this. The issue is how much you are saving back relative to the total size of your starter (and consequently how much you then end up pitching into your wort)

8oz is roughly 250mL. If you are doing a 3-4 L starter saving back 8 oz this isn't a big deal. If your starter is only 1L (pretty typical for a normal beer), you are talking saving back about a 1/4 of the total volume for this purpose. I would say that is a bigger deal. Even worse you are then underpitching by 25%.

Now if you up the size of your starter with the idea of saving some back...that would be workable.

As for generations and all that...those calculations can be done, but we brewers ball-park it anyway, so its not a huge deal whether you are saving yeast on the front or the back of the process.

 

[mobilecabinworks]

I realize this is an older thread but I read something on here somewhere about doing this and have not been able to find more info on this.

I'm thinking this is the way I'm going to proceed in the future. It makes sense to me to save the yeast from a controlled growth rather than from a variety of conditions in fermentation. Especially if you are doing large beers and braggots such as I am planning. It seems logical you risk less of a chance of mutation by controlling the growth phase each time. It also seems the math would not be too hard to figure for the amount you save, based against what you pitch.

Just looking for some conversion on this topic. Cheers.

 

[wilfonzo]

I'm going to try this, this week. Doing two brews with the same yeast... Doing the first brew this week, 1.048 OG, then in a week later doing a 1.051... So I went to Mr.Malty and figured out how much I needed for the first batch, 1L of 1.040 then added an extra 400ml to save for the next batches starter. Brew (1st batch) and place the leftover (still in flask) into the fridge and wait for the next batch and use the MrMalty, "repitch from slurry" tool to figure how many ml's I need for the next starter.

 

[Stauffbier]

I do this with all of the liquid yeast that I buy. I'll do a 1.5L starter then harvest half of that and use the other half to make a 2L starter then harvest half of that then make another 2 to 3L starter and harvest maybe a quarter of that and then pitch the rest into a batch. I end up with 3 jars with approx 90 to 130 billion cells each and the starter I needed for the batch I bought the yeast for. I start this about 7 days before I brew to allow for propagation and cold crashing in between starters.

 

[Polboy]

i do something similar but i freeze small samples of 1ml from starter slurry (pitch most of it, freeze 10-20ml) then whenever i need this strain i step it up to 1.5-3L