Author Topic: Less Awake Yeast vs. More dormant Yeast?  (Read 5352 times)

Offline Wildrover

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Less Awake Yeast vs. More dormant Yeast?
« on: June 15, 2009, 06:30:33 AM »
Is it better to pitch a yeast starter that is at high krausen which assuredly has fewer yeast cells than a yeast starter that has run its course but the cells now have to be re-awaken? 

The reason I ask is because somewhere along the way I ran into someone claiming that pitching the smaller amount of awake yeast produced for them quicker fermentation times with better attenuation.  This of course is anecdotal so I wanted to see if anyone else had some insight? 

Offline MaltLicker

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Re: Less Awake Yeast vs. More dormant Yeast?
« Reply #1 on: June 15, 2009, 09:36:33 AM »
I don't know exactly what the yeast cell count diff might be, but I can see how an active high-krausen starter could take off faster since the yeast are already eating.  (But those yeast are in the eating phase, and now they're in new wort with more oxygen, so does that throw them off too?)  There may be other variables that held back your friend's "reawakened" sample. 

One trade-off would be at high-krausen you'd be adding the spent wort to your beer:  probably OK with a stout, but perhaps not a kolsch or something else light/delicate. 

I like to pitch on the cool side of the range, so I've stuck with chilling the starter to ~54F to settle the yeast, dumping the spent wort, and pitching a few degrees cooler than my desired ferm temp.  I've also taken 8 oz of wort fm the boil at approx. 45 mins, cooled it, and poured into the starter slurry and put on stir plate to wake up the yeast, getting it used to the new wort profile before pitching the whole wort. 

dhaenerbrewer

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Re: Less Awake Yeast vs. More dormant Yeast?
« Reply #2 on: June 17, 2009, 10:43:51 PM »
Pitching at high krausen is absolutely the best thing to do. At this point, the yeast has gone anaerobic ( or is right on the verge ) and replication has stopped. So as far as having fewer yeast cells, I don't think that is the case. At high krausen the yeast is at it's most viable stage and will do very well if repitched.

Darin

Offline MaltLicker

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Re: Less Awake Yeast vs. More dormant Yeast?
« Reply #3 on: June 18, 2009, 07:17:28 AM »
....the yeast has gone anaerobic ( or is right on the verge ) and replication has stopped. Darin

I see how the starter cell count should be nearly identical.  But part of the total cell count includes the additional growth in cell count as yeast consumes the oxygen we pumped into the wort and buds some more, correct?  That yeast growth drives esters in the beer.  So what happens if the yeast are anaerobic (in starter) and eating (or shifting that way) and they are pitched into 5 gallons of wort with 10 ppm dissolved O2?   Do they stop eating and consume the O2 and resume budding new cells? 

On a home brew scale, do many of you dump the whole starter into the wort?  Have you ever thought you could taste the spent wort in your beer?  Or is that a wive's tale?

Offline Wildrover

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Re: Less Awake Yeast vs. More dormant Yeast?
« Reply #4 on: June 19, 2009, 11:13:03 AM »
The spent wort is something that I haven't thought of before.  I'm not really sure if I can taste it or not.  My last few batches have been pretty spot on though as far as my expectations and I don't think there is a taste.  Just thinking out loud (or whatever thinking into the keyboard is called) I'm not sure if you should taste the spent wort given that it is basically just sugar and yeast right?  I can see how too much might dilute the flavors of the beer you're making but in essence you're not adding anything different than what's already in the beer which is the flavors associated with the pale malt extract you used for the starter and the yeast right?  Isn't all of that already in the beer (assuming you made a beer with at least some pale malt)

I don't know though really, its something I haven't thought of before.

dhaenerbrewer

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Re: Less Awake Yeast vs. More dormant Yeast?
« Reply #5 on: June 19, 2009, 05:47:50 PM »
I've never had any issues with tasting "spent wort" in my beer. Like you said, it is generally a very light DME. There should be almost no residual sugar, and very little alcohol ( if you are using a stir plate ), so I can't see how it would affect the flavor. I've done this on a large scale, adding 150 gallons of yeast starter to a 1,000 gallons batch and never had any ill effects.

Darin