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Re: CO2 Questions

David Whittaker wrote:

> Mike Charlton said...
>>It is likely that the yeast will not fully ferment all the
>>sugar available.  Note that most people recommend recipes that result
>>in densities of 1100-1300.  I believe this is why many people find
>>DIY yeast generators unpredictible (sometimes going for 3 weeks, sometimes
>>going for 1 week, etc).
>
>This is very interesting. Does this mean that I've been wasting
>85% of the sugar in the generators?

Well, it's hard to say.  The best way to find out is to get a hydrometer
and test the density of the final solution.  If you have fermented all
the way out, the density should be about 0.990 or so (alcohol is less
dense than water, so the density will go below 1).  Anything more than
that represents unused sugar.

You can also taste the final liquid.  If it is at all sweet, then you
still have sugar left.  This isn't as good a way to do it.  Even without
the alcohol, a density of 1.020 is just barely sweet.  The alcohol will
mask the flavour even more.

I'm looking through the results of the CO2 experiment that David Lorenzen
did.  He ended up with final densities of between 1.020 and 1.030.  Now,
I can't remember what the original density was (about 1.120, I believe).
David also coaxed these bottles to produce as much CO2 as possible (at
one point keeping them in a 90 degree water bath).

I did a bit more checking.  1/4 cup of sugar (or about 62.5 ml) in 1 liter
of water has a density of about 1.020 (this will change greatly depending
on how finely the sugar is ground).  I have been using this for my CO2
generator (which I change every Sunday).  I measured the gravity of the
finished generator and got 0.995.

Today, I will put 1 cup of sugar in the generator.  In a couple of weeks
I will post the results.

          Cheers,
              Mike