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Old 12-22-2011, 04:38 PM   #21
Hex
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Can you include a picture of your test setup, and details of your methods?



 
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Old 12-22-2011, 05:10 PM   #22
tCan
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Sure. I'll include that in my post after fermentation stops. Though a single trial is hardly exacting science.

Edit: For the record, yeast is one of the most studied organisms in all of biology. I'm sure this information is already out there, and more reliable than what I'm doing.




 
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Old 12-23-2011, 03:11 PM   #23
Hex
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Quote:
Originally Posted by tCan View Post
I'm sure this information is already out there, and more reliable than what I'm doing.
You can include your historical references too!

 
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Old 12-23-2011, 03:25 PM   #24
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Awesome thread! Thanks!
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Old 12-23-2011, 03:30 PM   #25
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Ignoring until after peer review...

j/k, cool experiment. Thanks for putting it up here.
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Old 12-23-2011, 05:01 PM   #26
tCan
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I'm really surprised at how tolerant Saccharomyces is of alcohol. I didn't see any bubbles last night, but while I was sleeping, I picked up another percent ABV. They've barely slowed down at all, and I'm nearing 13% and my hydrometer has almost bottomed out. The end of the trial may be when there's no more sugar! A little bit of reading shows that reaching 13% is normal, with complete cell death at 14%. So we're probably going to see an abrupt ending here.

 
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Old 12-24-2011, 04:33 AM   #27
tCan
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Ok I'm just going to post the data I collected. I've included two charts which I think are the most interesting but you can obviously construct whatever you'd like from the data. I would have liked to overlay the two charts, but this doesn't seem possible with OpenOffice.

As per Hex's request, my methodology:

1 Welches white grape juice, with several inches of headspace plus sucrose (IG: 1.098, with an unmeasured combination of Hodgson Mill and Red Star active dry yeast. I assumed these yeasts to both be Saccharomyces cerevisiae, but possibly of different strains. This was done to try to improve the odds of getting an alcohol tolerant strain. Jug was left in room ~70F

The balloon was filled with water and then dumped into measuring cups and found to be almost exactly 1/2 cup or 115mL. The water probably stretched the balloon a bit, and some necking on the balloon would need to go around the mouth of the jug, so this was rounded down to 100mL. We're only looking for trend data here anyway.

When taking a CO2 reading, the balloon was pressed as flat as possible and allowed to inflate undisturbed. Time was called as soon the balloon stood upright. Two of these readings were taken, averaged, and then rounded to the nearest 5 seconds. The balloon method is too crude to assume anything more precise. This was done without moving the jug, making every effort not to jostle it which would release extra CO2, skewing the reading. Ambient temperature reading was taken at this time and used in the standard gas law equation to calculate mol CO2/sec: (n=(PV/RT))/sec

The jug was then moved to my bathroom sink area. Turkey baster, hydrometer, funnel and hydrometer testing tube are cleaned with antibacterial soap before every reading. Spinning or bobbing the hydrometer will remove bubbles from the hydrometer which can skew the reading. These Relative Density readings were used to calculate the ABV. The calculator at Winemaking Conversion Calculators - grapestompers was used as well as a table included with the hydrometer. These compose our alcohol % and alternative alcohol % respectively. In comparing a few online calculators, it seems the table included with the hydrometer errs a little on the high side, while the online calculator, a bit to the conservative. It is a safe bet that the actual ABV lies somewhere between the two. Again though, we're really only looking at the trend data.

Without further ado the spreadsheet: White Wine.xls

It's in .xls format. Let me know if there's any trouble, or if you'd like to know anything else I might have forgotten to mention here.

@HEX, I did take some photos, but I can't get them off my phone, it wont detect my microSD card, sorry. You're not missing out on anything you've not seen before, trust me.



 
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Old 12-24-2011, 05:45 PM   #28
Hex
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Too cool! Don't have much time at the moment, but I did have a good idea. Next time you run this, use a stopper and a mylar, party balloon, mass it empty(stopper and balloon), then when it fills, mass it again and subtract the difference. CO2 is very heavy, you will be amazed how much a full mylar balloon weighs. All you need is a gram scale, and your measurement will improve. (Volume is vary hard to measure compared to mass.)

Later.

 
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Old 12-24-2011, 07:01 PM   #29
tCan
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Why mylar? Are they easier to blow up or something?

Edit: Oh! Mylar! Yes. That would be interesting. Can't let it fill up all the way though. And that would be just about the saddest looking party balloon I ever saw!

 
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Old 12-25-2011, 02:47 AM   #30
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It might be interesting to fit a polynomial to the alcohol data and then take its first derivative. This should have the same shape as the gas evolution curve as gas evolution and alcohol production rate are proportional. I'd do it but the new Excel is not backward compatible and I can't open the spreadsheet.



 
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