Noticing Lower Brix > Alc Conversions in 2016-18

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Roy Piper
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Joined: January 27th, 2009, 1:57 pm

Noticing Lower Brix > Alc Conversions in 2016-18

#1 Post by Roy Piper » March 4th, 2019, 9:07 pm

Anyone else noticing lower conversions from brix to final alcohol lately? The last three years I find it has gone from .59-.60 to >.55-.57. That is up to 0.5% lower alcohol. Curious if other noticed this too.
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BenjaminL
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Re: Noticing Lower Brix > Alc Conversions in 2016-18

#2 Post by BenjaminL » March 14th, 2019, 7:39 am

Hey Roy, I think the horse is out of the barn trying to use Brix to forecast alcohol. Glucose/fructose content is a much more accurate predictor, Potential Alcohol (% vol) = glucose + fructose (g/L) / 16.83.
I think you are right noticing vintage variation in alcohol conversion due to differences in Glu/Fru: Brix ratios. Please look at this chart from ETS Labs out in Napa:
https://www.guildsomm.com/resized-image ... atio-2.jpg
it shows that even between cultivars there are large differences in Glu/Fru: Brix ratios. I'm still looking at this chart to try to find patterns, but its not easy.
Benjamin Leachman
www.forgottenunionwines.com

Eric Lundblad
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Re: Noticing Lower Brix > Alc Conversions in 2016-18

#3 Post by Eric Lundblad » March 14th, 2019, 11:04 pm

Brix is a fine measure for predicting alcohol, but you need to centrifuge your samples before testing. The real issue is getting a juice sample that's truly representative if your tank as a whole, a difficult thing to do with precision. And predicting the specific details of your fermentation can be tricky...the amount of non-Sacc C yeast fermenting, the amount of alcohol that blows off during the heat of fermentation, and other related issues.

But, at the end of the day, the amount of alcohol that a Sacc C yeast produces from a fixed amt of sugar as input to the yeast is pretty fixed.
Ladd Cellars
Winemaker & Owner

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