user 55733
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Doing a project in Microbiology, we have two set-ups, aerobic and anaerobic.
We are calculating alcohol using specific gravity, does this still apply for the aerobic set up as not all of the yeast will be metabolizing the sugar into ethanol.
Basically I'm asking would the same equation apply for the aerobic batch as the anaerobic batch?
I'm using this calculation BTW, nothing too complicated (I got the same, using Beersmith)
Here are my current calculations, I've copied and pasted it from my report so sorry if it's a bit long winded...
The specific gravity was measured at the beginning and end of the experiment to enable the calculation of alcohol content/alcohol by volume in the final product.
It also requires two constants (Hough [1985]):
 1.05 g which refers the amount of carbon dioxide produced for every gram of ethanol produced (constant 1)
 0.79 g/ml which represents the density of ethanol alcohol (constant 2)
Aerobic Experiment
 Original Gravity Reading (OR) = 1.030
 Final Gravity Reading (FR) = 1.010
OR - FR = 1.030 - 1.010
= 0.02 g/ml
(0.020 g/ml refers to the amount of carbon dioxide that has bubbled off)
Constant 1 x Amount of CO2 Bubbled off = 1.05 x 0.02
= 0.021
Ʃ (Constant 1 x Amount of CO2 Bubbled off) 0.021 ----------------------------------------------------------------- = ------------ Final Gravity 1.010
= 0.02079
0.02079 0.02079 ------------------- = -------------- Constant 2 0.79
= 0.0263
(%) = 0.0263 x 100
= 2.63 % alcohol by volume (a.b.v)
Thanks for reading
We are calculating alcohol using specific gravity, does this still apply for the aerobic set up as not all of the yeast will be metabolizing the sugar into ethanol.
Basically I'm asking would the same equation apply for the aerobic batch as the anaerobic batch?
I'm using this calculation BTW, nothing too complicated (I got the same, using Beersmith)
Here are my current calculations, I've copied and pasted it from my report so sorry if it's a bit long winded...
The specific gravity was measured at the beginning and end of the experiment to enable the calculation of alcohol content/alcohol by volume in the final product.
It also requires two constants (Hough [1985]):
 1.05 g which refers the amount of carbon dioxide produced for every gram of ethanol produced (constant 1)
 0.79 g/ml which represents the density of ethanol alcohol (constant 2)
Aerobic Experiment
 Original Gravity Reading (OR) = 1.030
 Final Gravity Reading (FR) = 1.010
OR - FR = 1.030 - 1.010
= 0.02 g/ml
(0.020 g/ml refers to the amount of carbon dioxide that has bubbled off)
Constant 1 x Amount of CO2 Bubbled off = 1.05 x 0.02
= 0.021
Ʃ (Constant 1 x Amount of CO2 Bubbled off) 0.021 ----------------------------------------------------------------- = ------------ Final Gravity 1.010
= 0.02079
0.02079 0.02079 ------------------- = -------------- Constant 2 0.79
= 0.0263
(%) = 0.0263 x 100
= 2.63 % alcohol by volume (a.b.v)
Thanks for reading