[APD] 'diy yeast' observation and thought

[Sean Fritz <ealar at mac_com>]

I have been experimenting with 'diy yeast' co2 injection for a few 
weeks (documented at 
http://isnot.org/wiki/wiki.pl/Co2_Injection_System).  I have made one 
interesting observation.  Also, it has perked my interest in 
winemaking/hard cider making and I have started looking into 
'drinkable' co2 production which lead me to notice a paragraph 
describing vinegar bacteria as resulting in only h2o and co2 as the end 
products.

The 'white bacteria' that several people reported growing near the exit 
airstones of their tanks appears to be alcohol thriving, not a product 
of the yeast itself.  When I was running my yeast gas through a pool of 
vodka (you use vodka for the exit valves of brewing equipment, that's 
where I got the idea) the cloud around my airstone was extremely large. 
 It had no ill effect on my fish and wasn't taking anywhere else in the 
tank.  After a few days of thriving on the airstone it also appeared 
that a small culture was growing in my 'cleaner' bottle (which should 
have had a high enough alcohol concentration to kill the bread yeast I 
was using).

I then made two changes at once (sorry, I know I shouldn't have but I 
really wanted to try to make hard apple cider).  I siphoned out all the 
vodka-water from the 'cleaner' bottle, and replaced it with about three 
cups of RO water (after running some bleach and several gallons of hot 
water [not boiling] through the bottle).  I also replaced my co2 
generation gunk (previously yeast/flour/sugar/water) with apple juice, 
sugar, and yeast.  The bacteria culture around the airstone died off 
(and floated around the tank in large chunks before finding the filter) 
inside of a day.  I am not 100% positive that the change that had an 
effect was the RO water in the 'cleaner' bottle, but I think it makes 
sense.  If anyone would like to run a few more experiments it might be 
very informative.

Also, I was reading up on winemaking today and I ran across this page  
http://home.att.net/~lumeisenman/chapt1.html which I quote:

"Depending upon the winemaking conditions, several other fermentations 
can and often do occur in wine. Some bacteria can ferment the glycerol 
in the wine into lactic and acetic acids. The natural grape sugars can 
be transformed into lactic and acetic acid by other types of bacteria. 
A few species of bacteria can ferment the tartaric acid in the wine 
into lactic acid, acetic acid and carbon dioxide gas. Vinegar bacteria 
can convert the alcohol into acetic acid. Then the same bacteria 
convert the acetic acid into water and carbon dioxide gas. These other 
transformations can produce several materials that detract from wine 
quality. Byproducts of these undesirable fermentations can be 
devastating, and when these fermentations occur, wine is often called 
"diseased" or "sick."

If I am reading that correctly (look for the "Other Fermentations" 
heading) it states that vinegar bacteria will help create a 'stable' 
co2 production factory with the only end product being water and dead 
bacteria (and one would think 'recoverable' simply by adding sugar).  
Does anyone have experience with this?  It sounds interesting.

--
Sean Fritz

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