Yeast Propagation Help/Info

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Otterbaub
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Yeast Propagation Help/Info

Post by Otterbaub »

Getting back into the saddle of brewing i have a question and yeast propagation.

I picked up some White Labs liquid yeast this week and was informed by the guy at O'Shea's that i could multiply the yeast in to 9 different parents. He gave me a piece a paper with 8 steps and no more than a sentence on each step. I would imagine that there is a little more science to it than the Betty Crocker instructions that i got.

i am a former baker so i feel i understand yeast pretty well in the aspect of how not to kill it via temp and lack of food. I have heard stories of people trying to take San Fransisco yeast starter to New York to make sourdough, but the yeast always changes after one or two batches of bread. What is to stop my liquid yeast from changing in to something completely different?

This is the first time i have worked with liquid yeast as well . Any information or general direction would be much appreciated.

The yeast i have is British Ale Yeast, any suggestions on extract recipes would be gladly taken.
Beer is like bread just in different ratios.
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lexuschris
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Re: Yeast Propagation Help/Info

Post by lexuschris »

Welcome back to brewing!

There are some good articles & youtube videos out there covering yeast propagation (yeast starters). I started out with this article at mrmalty.com.

The White Labs liquid yeast vials have enough yeast cells to properly ferment a 5-gallon batch of beer, provided it is of medium gravity (< 1.060 OG). Just let the vial warm to room tempature while you are starting your brew day. Bring your finished wort down to pitching tempature (I like 75-80-F) and make sure you aereate it well. Vigorous shaking or pouring is good. Air stone or O2 wand is better. After pitching bring your wort down to fermentation temp.

As for re-using yeast, there are various articles on yeast 'washing' or 'cropping'. These take healthy live yeast directly out of the fermenter, either after you rack off the yeast pack at the end of primary, or cropped off the top of the fermenting beer.

Generally, there is always a chance for mutations & infections. I've heard the recommendation to not re-use yeast more than 5 times, although I've heard lots of folks go well past that too. Always be sure you have well sanitized equipment & utensils when washing yeast.

Hopefully a few others can chime in and explain this a bit better, or correct my generalizations.. :)

Good luck!
--LexusChris
"A woman drove me to drink, and I hadn't even the courtesy to thank her." – W.C. Fields
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brahn
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Re: Yeast Propagation Help/Info

Post by brahn »

I agree with lexuschris: read JZ's article at mrmalty.com. It's really great information on propagating yeast.

The yeast manufacturers do market the vials and Wyeast smack packs as being pitchable into 5G of moderate gravity wort. However, those packages contain about 100B very healthy live yeast cells on the day they're manufactured. Using a fairly standard ale pitching rate of 750 million cells per milliliter per degree plato, 5G of 1.060 wort would require just over 200B cells. This is not to say that you won't make beer, even good beer, by just pitching one of the vials/smack packs. Just know that you will most likely be producing more esters and other fermentation byproducts than you may want. I'd suggest checking the pitching rate calculator to get a better idea of how much yeast you need.

I think 75-80 is pretty high for pitching temp. Unless you're trying to stress the yeast and create more esters/phenols/etc I would recommend pitching at or below your target fermentation temperature.
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