Splitting a yeast smack pack on brew day between 2 5-gallon batches

Disclaimer: I used the search function but didn't really see any results that pertain to my situation (maybe I used the wrong keywords).


I have only done 1 batch before today, an American IPA where I used dry yeast. I recently got my buddy interested and he purchased a starter kit and an ingredient kit.

Today was our planned brew day, he was planning on coming over to my house and we would each make a batch. The problem is I forgot to tell him to get yeast and the home brew store is closed on Sundays.

I have an Activator Wyeast American ale liquid yeast smack pack with supposedly 1 billion yeast cells which I have yet to activate. Would it be possible and/or advisable to split this between both of our batches without having taken any prior steps?

There are a few variables that you need to account for when pitching the yeast: volume of wort, original gravity and amount of yeast you have on hand. Usually i do yeast starters with liquid yeast that coincides with what http://www.mrmalty.com/calc/calc.html says is a viable pitching amount.

It doesn't seem that you did a yeast starter so you may be already underpitching your wort. I wouldn't recommend splitting your single smack pack. In the future you should look into making a yeast starter to adequately pitch the correct amount. There are a bunch of threads regarding the benefits of doing this and also a sticky somewhere that gives a basic description of creating a yeast starter.

Possible, but not advisable. The term you want to search for is "underpitching". You'll likely get a slow fermentation with off flavors. There is some controversy about proper pitching rates, but half of an activator is low by any metric.

(BTW, an activator has 100b cells, not 1b)

Make a starter out of the wort and pitch it when it's ready. You can leave you wort for a few days in the carboy with out a problem.

ShakerD said:

Make a starter out of the wort and pitch it when it's ready. You can leave you wort for a few days in the carboy with out a problem.

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That's a great way to get an infection too. Make a starter prior to doing it... you'll be way underpitching with 2 batches

veritas524 said:

That's a great way to get an infection too. Make a starter prior to doing it... you'll be way underpitching with 2 batches

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Please explain what you mean here. The part about the infection.

ShakerD said:

Please explain what you mean here. The part about the infection.

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I'm going to have to agree with veritas on this one. A carboy full of warm wort is a great habitat for errant bacteria. Pitching a few hundred billion yeast cells right after boil usually means that the bacteria can't get an active foothold, but a couple of days head start makes for a very different situation. You could have some pretty nasty wort by the time you had yeast ready to go.

If you can get the wort down to <40F quickly and if you have excellent sanitation procedures, you might be okay. Judging by the OP's question, though, I'm guessing he's relatively new to brewing (no disrespect intended) and likewise I don't expect that either of those are safe assumptions.

Wow I am surprised by the response.

You guys should check out the no chill method. There are people that no chill and leave the wort for months before they pitch. As long as sanitation is done properly leaving wort for a few days shouldn't be a problem.

NO CHILL WIKI

Cheers

ShakerD said:

Wow I am surprised by the response.

You guys should check out the no chill method. There are people that no chill and leave the wort for months before they pitch. As long as sanitation is done properly leaving wort for a few days shouldn't be a problem.

NO CHILL WIKI

Cheers

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I've done no chill, and think it's perfectly effective. But like I said, I'm not going to assume the OP's sanitation is solid considering that this is the beginner's forum. I can sterile wort for starters and have jars that are six months old and that are still perfectly fine. But I've also seen wort go putrid in a couple of days.