Author Topic: Fermentation and High OG  (Read 3514 times)

Offline a10t2

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Re: Fermentation and High OG
« Reply #15 on: November 21, 2009, 10:31:20 AM »
That still works out to an FG of 1.011. I downloaded BeerAlchemy and plugged those numbers in, and it gave me 1.012. Are you sure you're entering the right inputs (current Brix reading, and OG in SG)?
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Offline bendbrew

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Re: Fermentation and High OG
« Reply #16 on: November 21, 2009, 11:09:33 AM »
You're right-I entered it wrong.  Thanks for the correction.  What I don't understand is when I tested it with they hydrometer at the same time it read 1.022 at 68%.  That is a large discrepancy.  I will retest either today or tomorrow

Offline a10t2

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Re: Fermentation and High OG
« Reply #17 on: November 21, 2009, 01:23:22 PM »
I've never seen a discrepancy that large, but in my experience the refractometer correlation rarely agrees with a hydrometer reading.
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Offline wilypig

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Re: Fermentation and High OG
« Reply #18 on: November 23, 2009, 07:58:48 AM »
One thing to remember about yeast and O2 is that in the presence of O2 yeast will want to reproduce and will not start any noticeable fermentation until the Lag phase (all O2 used up) is done. The more O2 you use the longer the lag time but the shorter the actual fermentation due to overall cell count. 
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Offline denny

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Re: Fermentation and High OG
« Reply #19 on: November 23, 2009, 09:59:23 AM »
I thought that the Crabtree Effect said that in the presence of a >.5 % glucose solution that fermentation starts immediately.  Incorrect?  Or is that what you were referring to by "noticeable fermentation"?

One thing to remember about yeast and O2 is that in the presence of O2 yeast will want to reproduce and will not start any noticeable fermentation until the Lag phase (all O2 used up) is done. The more O2 you use the longer the lag time but the shorter the actual fermentation due to overall cell count. 
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Offline a10t2

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Re: Fermentation and High OG
« Reply #20 on: November 23, 2009, 11:25:22 AM »
That's my understanding of the Crabtree Effect as well, although the yeast will still respire aerobically until all the O2 is consumed. Otherwise there would be no reproduction in wort at all.
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