Author Topic: Original gravity affect on yeast  (Read 616 times)

Offline james_cornell

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Original gravity affect on yeast
« on: November 26, 2014, 04:41:23 AM »
So, since I am still getting a feel for my new equipment, I brewed the same recipe two nights ago and last night, only difference was my sparging technique.

Two nights ago I tried fly sparging through a strainer and got a pretty low mash efficiency, approx 60%.  I was aiming for a final volume of 1.25 gal with an original gravity of 1.071.  I ended up with approx 1.35 gal (played with the stove a little much when boiling) and an original gravity of 1.050.  I used a Wyeast british ale smack pack which i started before i started to brew and was inflated by the time I pitched.  Since these were small batches I pitched half the pack and poured the other half in a sanitized mason jar topped with aluminum foil and left it in the fridge ( i know it was exactly half because I actually poured it out into two same sanitized mason jars first to make sure it was split even).

The next night I batch sparged, got a mash efficiency of approx 65% and ended with a final volume of approx 1.11 gal (got a better feel for the stove after last night and managed to keep it at a roaring boil without boiling over so I lost more due to boil off) with an original gravity of 1.066. Then I pitched the leftover yeast.

After 48 hrs since the first batch and 24 hrs since the second, the airlock in my second batch has a healthy amount of activity and the airlock in my first has none. Other than the fermenting bucket and the issues described above, nothing is different between the two.

Now here's my question, if we ignore the possibly of the fermenting bucket lid not sealing, would the lack activity be due to the lower gravity, since there is less sugar and all?

I am still new to brewing but this is the second batch I have made in the 1.050 and neither shows activity although the first did ferment so maybe at that low of a gravity it doesn't show in the airlock? 

Offline a10t2

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Re: Original gravity affect on yeast
« Reply #1 on: November 26, 2014, 04:51:34 AM »
Unless there's a difference in temperature, you can be 99.9% sure they're both fermenting and that it's a poorly sealed fermenter. Is there no krausen on the batch with no airlock activity?
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Offline james_cornell

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Re: Original gravity affect on yeast
« Reply #2 on: November 26, 2014, 05:00:44 AM »
I cracked the lid.  There is a little krausen, or I assume thats krausen, and it smells somewhat beerish.  I'm not super concerned that it's not fermenting, just looking for an explanation as to why I see so much activity in half the time in one and none in twice as much time in the other.

I know a lid not sealing is a probable answer but I was wondering if the amount of sugar might also slow down or delay the fermentation.

Also the Wyeast had an additional 24 hours in the fridge before it was pitched in the second batch. Im assuming thats  another plausible variable.

Offline james_cornell

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Re: Original gravity affect on yeast
« Reply #3 on: November 26, 2014, 05:01:26 AM »
P.S. why don't you like Chico?

Offline majorvices

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Re: Original gravity affect on yeast
« Reply #4 on: November 26, 2014, 12:51:33 PM »
I cracked the lid.  There is a little krausen, or I assume thats krausen, and it smells somewhat beerish.  I'm not super concerned that it's not fermenting, just looking for an explanation as to why I see so much activity in half the time in one and none in twice as much time in the other.

I know a lid not sealing is a probable answer but I was wondering if the amount of sugar might also slow down or delay the fermentation.

Also the Wyeast had an additional 24 hours in the fridge before it was pitched in the second batch. Im assuming thats  another plausible variable.

It is possible you see less activity due tolower gravity wort. but it is also a probability that you did not split your yeast completely evenly since it appears you just "eye balled it". So cell count is probably a bigger factor. Along with the bucket lid not seated properly. To be honest, if you make sure you have aerated properly and have pitched an appropriate sized pitch of a healthy yeast you won't need to concern yourself with airlock activity or the amount of krausen. You will be confident that you will have a solid fermentation everytime.

Offline HoosierBrew

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Re: Original gravity affect on yeast
« Reply #5 on: November 26, 2014, 01:33:30 PM »

It is possible you see less activity due tolower gravity wort. but it is also a probability that you did not split your yeast completely evenly since it appears you just "eye balled it". So cell count is probably a bigger factor. Along with the bucket lid not seated properly. To be honest, if you make sure you have aerated properly and have pitched an appropriate sized pitch of a healthy yeast you won't need to concern yourself with airlock activity or the amount of krausen. You will be confident that you will have a solid fermentation everytime.

+1
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Offline a10t2

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Re: Original gravity affect on yeast
« Reply #6 on: November 26, 2014, 05:11:36 PM »
P.S. why don't you like Chico?

It screws up my brewing schedule because it takes so long to drop bright. I see no reason to use it when more flocculent strains with very similar flavor profiles are available.
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