Splitting a Starter into 2 Batches

Hi All,

I've searched and searched and cannot find an answer to this question...apologies if this has been covered before (I imagine that it has been).

Friday I'm planning on brewing a Bourbon Barrel Porter (OG 1.065) and a Winter warmer (1.047)...both 5 gallon batches. In both, I am using a Wyeast Scottish Ale smack pack. I have two smack packs on hand but was thinking about making a large starter and splitting it between the two batches since I am brewing the same day. This way, I can use the other smack pack to make a Scottish 60 one night next week.

I've made plenty of starters before but I have never split a starter between two batches so I'm wondering how much I should make. Last night I made a starter with 2 cups xtra light DME and 32 oz water. Since I plan on brewing on Friday, I was going to put it in the fridge to get the yeast settle, decant, and pitch half the slurry in each batch.

Do I have an adequate amount of yeast to do this with the size of starter that I made or should I step it up when I get home tonight? I know I'd probably be fine either way but just wondering what people think.

Thanks!!

Unfortunately, that won't be a big enough starter. You can definitely split a starter, but the starter size must be large enough to propagate enough yeast required to ferment both batches. In your case, it is going to be at least a one gallon starter, possibly more depending on the viability of your yeast.

Also, if you do a large starter like this and split it, be sure to step up the starter -- i.e., don't just pitch the yeast in 1 gal of wort. Instead, make a 1 quart starter first, then 'step-up' the volume to 1 gal or more. You will make a lot more yeast this way, particularly if you provide the starter wort with lots of oxygen.

I concur with Flyguy on this one. 2 days isn't really enough time to get a sufficient cell count up from a split starter from a smakpack, even with a stirplate like I use. You could get away with it, and prolly come out with good beer, but I'd prefer to have at least a step or two in there to build the cell count.

Thanks for the help. I'm glad I asked this question.
I'll just pitch this starter into the Bourbon barrel porter and then make another for the winter warmer. I'll make the winter warmer starter tonight...

Do you think I should step up the bourbon porter starter or do you think that 1 quart starter I made last night is enough?

What's your anticipated OG for the Porter?
If it's fairly high, ie. 1.065 or higher, I'd go one more step, but if it's a regular strength porter, you're fine.

It's 1.065. Thanks for the advice. I'll step it up tonight.