One Yeast = 2 Brews

[ryandlf]

I am going to be using a WLP007 yeast on 2 separate brews that I plan on brewing back to back. I usually make a 0.25 gallon starter with DME the night before brew day. Instead, can I make my usual starter 3 days before hand, then a day after add another 0.25 gallons of DME, let sit for the remaining day and pitch half into one brew and half into the next? Will 3 days be enough time to allow enough yeast to multiply so I am not under pitching?

And on a side note. I have been asking a ton of questions lately and have had nothing but amazing feedback and advice from all you HBT brewers. I am truly thankful for websites like this one...so thank you to everyone who has taken a moment of time out of their life to help a novice noob like me

 

[joety]

I think you will be under pitching. Check MrMalty, and plug in 10 gallon batch size. You will have to be careful to split it in two appropriately.

I am guessing, depending on gravity, you'll need a full gallon starter, not 1/2 a gallon.

 

[ryandlf]

The reason I am using a half gallon is because I usually use a half gallon jug, half way full for a starter. I was hoping by fermenting for 3 days as opposed to my typical overnight that I would actually be replicating and producing twice the amount of yeast, as opposed to just sort of waking them up.

 

[joety]

The reason I am using a half gallon is because I usually use a half gallon jug, half way full for a starter. I was hoping by fermenting for 3 days as opposed to my typical overnight that I would actually be replicating and producing twice the amount of yeast, as opposed to just sort of waking them up.

That only works if you start with twice as much as well.

 

[ryandlf]

How does "reproducing" yeast only work if you pitch twice as much of an original culture? When I pitch into my wort and let it ferment for a week I end up with a considerable amount more after I rack the beer off.

 

[stageseven]

There is only so much that yeast will be able to reproduce given a set amount of wort and starting yeast. I'm not sure of the exact numbers, but one of the things Chris White goes over in his book on yeast is starter sizes, and how you get diminishing returns by upping the volume of starter with the same amount of yeast. 1L to 1 vial is optimal for a 1.035-1.040 stater wort to get a doubling of the yeast, but it doesn't keep the same linear level of increase as you increase the amount of starter wort.

That's where joety's math comes in. After your initial doubling, you need a greater volume of wort for another doubling, hence the 2L step up size instead of another 1L. Your idea will get you more yeast than not stepping it up at all, but not as much as following joety's recommendation.

 

[rp5brew]

If both your brews are 15P or less than a 1 gallon starter in two 2 quart steps should be sufficient. I would recommend chilling and decanting your starter, divide it I half and toss a little 16-24floz of your first brew wort in the remaining slurry to keep it happy until you pitch into the second brew.

If you go to wyeast labs they have a pitch calculator to figure out your pitch rate, commercial rates according to Palmer are 1 million cells/ml per degP of wort. So 15P=15 mil cells/ml.

5 gallon batches yes?

 

[ryandlf]

Yes both 5 gallon batches. Ok so I think I understand now it's just going to take slightly longer. I'm going to let the yeast consume all the usable sugar in its original 2L's of wort, then chill and decant the liquid and add another 2L which should hopefully get me enough yeast for both batches.

 

[rp5brew]

That's one way- a two step 2L starter should be enough though- and you don't have to decant between steps, just pour the new wort in. 1L steps

 

[bullinachinashop]

No one has asked what your starting OG will be. The OG has everything to do with cells needed.
So you need to give more information about the beers your brewing before anyone can give you an accurate answer.
Bull

 

[McKinley]

Why not top crop? Do you have to brew these both on the same day? Seems easier than all this math.

 

[ryandlf]

I didn't realize I could just pour the new wort on top of the old stuff, but ya i'll do that instead.

OG's...I will have to look at promash as I don't remember. I know the first beer is an Oatmeal porter so its going to be around 1.057 I think and then second a Black IPA which will start somewhere around 1.080.

Top cropping? Is that when I siphon some of the yeast off the top of the beer while its fermenting? Not sure how to do that because I ferment in better bottles.

 

[rp5brew]

Whoa-

The IPA would need a .5 gal starter just for it- I would not recommend splitting a single vial for those, even with a starter. they both are higher gravity, especially the IPA.

 

[ryandlf]

Hmm...ok. Maybe i'll just stop being cheap and buy another vial of 007. How about top cropping? If I brew one batch this week and the other next week can I top crop somehow with a better bottle and reuse the yeast?

 

[joety]

No one has asked what your starting OG will be. The OG has everything to do with cells needed.
So you need to give more information about the beers your brewing before anyone can give you an accurate answer.
Bull

Correct, that's why I said "depending on gravity". I was estimating based on the sufficiency of the 1 quarter starter he uses for 5 gallons, which would only cover moderate gravity beers.

 

[marc06]

Unless your stuck having to brew on the same day, the first beer gives you a nice yeast cake for the second. If you have to brew on the same day... you need more yeast.

 

[bullinachinashop]

The vial by itself will be sufficient for the first batch as long as it's fairly fresh.

The second batch will require more cells and can be taken from your primary yeast cake after a couple of weeks. This can be done by simply siphoning some off the bottom of your primary and measuring the amount as a thin slurry in mrmalty's pitching rate calculator.

Top cropping is more of an art and difficult to determine the amount of yeast you are collecting. Maybe something to try on a session beer.

If your growing your yeast from 1 vial for the second batch, then you would need to multi-step a starter with 2-1 liter steps or make 1 large starter of 4.5 quarts.

Good luck

Bull