Re: vinegar eels, surface scum

["Tyrone Genade" <Tgenade at sun_ac.za>]

On 28 Aug 2002, at 13:07, Rjga at aol_com wrote:

> nothing is wrong. The scum is probably yeast. You should still have
> plenty of vinegar eels in there, although the juice would use up much
> faster than a slice or chunk of apple.

The odds are the scum is an Acetobacter and/or Gluconobacter biofilm 
(these guys are aerobic and need air!). Any yeast would of been 
killed by the acetate (they have a very poor acetate tolerance, poor 
buggers...).

I agree with the idea that the population drop was because of an 
burst of ethanol produced from the sugar in the juice. The apple also 
has sugar (lovely fructose!) but this is less accessable to the 
bacteria that produced the ethanol. So, I have to also agree with 
Robert as the juice was certainly used up much faster than the apple. 
With the apple the fermentation would of been slow and the 
Acetobacter and Gluconobacter would of been able to convert the 
ethanol to acetate evenly. The ethanol probably overwhelmed them and 
the eels both. The good news is that both will recover in time!

I've found vinegar eels to have a long lag phase in growth regardless 
so you may just no be seeing anything at this time Paul. Have a 
little patience.

As a side not Glucobacter liquifasciens (formally Acetobacter) is a 
nasty pest in the Hawain pinaplle industry where the bugs destroy the 
ripe pinaplles.

Also, yeast will precipitate in most unfriendly environments except 
ale where they will flocculate and float to the top.... go figure. In 
the bear brewing process the yeast will flocculate and sink to the 
bottom. The same occurs in batch culture in the lab on plain glucose. 
The acetobacter etc.. always rise to the top where they can form 
paper like sheets (they produce massive amounts of cellulose and 
research is under way to try and harvest this for the paper industry 
etc...).

tt4n

Tyrone Genade
tgenade at sun_ac.za
http://www.tyronegenade.0catch.com
cell#: 084-3354-977

*************************************************************
P450 Lab, Biochemistry Department
University of Stellenbosch, 7602, South Africa
Ph: +27-021-808-5876, fax: +27-021-808-5863
**********************************************************

"Seek your happiness in the Lord."
                  Psalms 37:4

---------------
See http://www.aka.org/AKA/subkillietalk.html to unsubscribe
Join the AKA at http://www.aka.org/AKA/Applic.htm