Hello everyone, newbie here to both brewing and the forum. I have been on a diet that consists of very low sugar intake and llow carbs. One thing I really rreally miss is root beer, but of course I can not consume regular soda because of diet. I want to get into brewing my own root beer from an old recipe I has found. The recipe calls for 2.5 quarts of water and 2 cups of sugar. So at that rate there will be approximately 1.5 grams of sugar per fluid ounce before fermentation. That's a tad high for me still. My question is, roughly how much of that sugar will be consumed in theffermentation process? Thanks!

Welcome, Xandrew245!

Our resident brewmaster, aruzinsky, might be able to guide you on the sugar fermentation process. But you might want to consider using carbonated water / carbon injection instead. That might require changes to the recipe, but might taste more like what you're used to buying off the shelf.
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Kevin Guske

So heres a tribute toast with root beer in hand to you and the many mugs of suds along your happy trails. --Charles Wysocki, artist and root beer fan, 1928-2002

Xandrew245x wrote:

My question is, roughly how much of that sugar will be consumed in theffermentation process?

The reduction in the weight of sugar will be approximately proportional to the increase in alcohol or carbon dioxide according to the chemical reaction:

C6H12O6 + Zymase → 2 C2H5OH + 2 CO2

The molecular weights are as follows:


C6H12O6 - 180
C2H5OH - 46
CO2 - 44

The reduction in weight of sugar will be 180/(2*44) = 2.045 times the weight of carbon dioxide.

According to http://www.manualslib.com/manual/383616/Eutech-Instruments-Carbon-Dioxide-Gas.html?page=13 ,
the maximum carbon dioxide concentration of carbonated beverages is 880 ppm or 0.00088. The weight of one fluid ounce of solution is approximately 29.57 g., therefore the reduction in sugar will be, at most, 2.045*0.00088*29.57 = 0.53 g/oz.

aruzinsky wrote:

Xandrew245x wrote: My question is, roughly how much of that sugar will be consumed in theffermentation process? The reduction in the weight of sugar will be approximately proportional to the increase in alcohol or carbon dioxide according to the chemical reaction: C6H12O6 + Zymase → 2 C2H5OH + 2 CO2 The molecular weights are as follows: C6H12O6 - 180 C2H5OH - 46 CO2 - 44 The reduction in weight of sugar will be 180/(2*44) = 2.045 times the weight of carbon dioxide. According to http://www.manualslib.com/manual/383616/Eutech-Instruments-Carbon-Dioxide-Gas.html?page=13 , the maximum carbon dioxide concentration of carbonated beverages is 880 ppm or 0.00088. The weight of one fluid ounce of solution is approximately 29.57 g., therefore the reduction in sugar will be, at most, 2.045*0.00088*29.57 = 0.53 g/oz.

CORRECTION:

I made two mistakes.

1. "880 ppm" is wrong. I misread the reference.

2. 2.045*0.00088*29.57 = 0.053 g/oz (not 0.53)

From

http://chemistry.stackexchange.com/questions/9067/what-is-the-carbon-dioxide-content-of-a-soda-can-or-bottle ,

the carbon dioxide concentration of Coca Cola is 6197 ppm. At that concentration, fermentation would reduce sugar by

2.045*0.006197*29.57 = 0.3747 g/oz

aruzinsky wrote:

aruzinsky wrote: Xandrew245x wrote: My question is, roughly how much of that sugar will be consumed in theffermentation process? The reduction in the weight of sugar will be approximately proportional to the increase in alcohol or carbon dioxide according to the chemical reaction: C6H12O6 + Zymase → 2 C2H5OH + 2 CO2 The molecular weights are as follows: C6H12O6 - 180 C2H5OH - 46 CO2 - 44 The reduction in weight of sugar will be 180/(2*44) = 2.045 times the weight of carbon dioxide. According to http://www.manualslib.com/manual/383616/Eutech-Instruments-Carbon-Dioxide-Gas.html?page=13 , the maximum carbon dioxide concentration of carbonated beverages is 880 ppm or 0.00088. The weight of one fluid ounce of solution is approximately 29.57 g., therefore the reduction in sugar will be, at most, 2.045*0.00088*29.57 = 0.53 g/oz. CORRECTION: I made two mistakes. 1. "880 ppm" is wrong. I misread the reference. 2. 2.045*0.00088*29.57 = 0.053 g/oz (not 0.53) From http://chemistry.stackexchange.com/questions/9067/what-is-the-carbon-dioxide-content-of-a-soda-can-or-bottle , the carbon dioxide concentration of Coca Cola is 6197 ppm. At that concentration, fermentation would reduce sugar by 2.045*0.006197*29.57 = 0.3747 g/oz

Sorry, I made another mistake, C6H12O6 is glucose, not sucrose (common sugar). But, my last answer would have been correct, had you used glucose instead of sucrose.

According to http://en.wikipedia.org/wiki/Ethanol_fermentation ,

"Alcoholic fermentation converts one mole of sucrose into four moles of ethanol and four moles of carbon dioxide, producing two moles of ATP in the process."

The formula for sucrose is C12H22O11 and its molecular weight is 342. The molecular weight of carbon dioxide is 44. Thus, the mass ratio of sugar to carbon dioxide is 342/(4*44) = 1.943 and the reduction in sugar per ounce of soda is approximately 1.943*0.006197*29.57 = 0.356 g/oz.