Re: Starch, yeast and alcohol

[George Slusarczuk <yurko at warwick_net>]

Hello Bill,

You are absolutely right -- many foods, particularly bread, contain
yeast. Yeast makes dough rise. It is killed during baking.

Yeasts can ferment sugar (usually sucrose) or starch (starch is
polymerized glucose, a sugar).

Fermentation of sugar is simpler and faster than that of starch, but on
a larger scale, much more expensive.

Commercially, alcohol (ethanol) is produced by fermenting starch
--mostly crushed grain, corn, or potatoes -- and distilling alcohol from
the "mash". 

The different taste of the several fermentation end products depends on
the starting material, kind of yeast, fermentation conditions (and
distillation, if used). Many variables, thus so many different varieties
of the end products available to us.
 

The controversy and different methods of raising "Daphnia" is, I think,
due to a large extend to differences in the critters people keep. There
are, literally, dozens of Daphnia species. Then there are other
Cladocerans -- Moina, Bosmina, Ceriodaphnia, Sida, Latonia, etc., etc.
On top of that, each Cladoceran species usually has many different
races, with different culture requirements. 

For an amateur, it is practically impossible to determine which species
it is that he keeps. Good if the genus can be established! Even
specialists have difficulty distinguishing between many described
species, never mind races.....

So, one either experiments with different conditions, or -- what I
generally do -- select culture conditions that suit me, and then try to
find critters that will grow well under those conditions.

Either way, the culture will go well for months or years and then,
suddenly, crash. That is why backup cultures are essential.

Best,

George


Date: Sat, 25 May 2002 17:37:59 EDT
From: Billinet at aol_com
Subject: Re: Raising Daphnia - Flour and Alcohol

Matt said, in part:

"The only reason that I can think of for not using activated yeast is if
you are also using FLOUR to feed your Daphnia. Yeast + flour will start
a fermentation, producing alcohol, that eventually will kill the
Daphnia."

Well, not in my experience.  I've been raising daphnia for at least 4
years 
on a soy flour - yeast mixture and it's worked great!  I've never had a 
die-off.  

Can you furnish a reference?  Yeast is a common ingredient in many
foods.

I don't know much about the production of alcohol; I'm more at the
consuming 
end.
I do know that it is a chemically complex process, but it all seems to
start 
with the fermentation of sugar.  To make it you need a lot of sugar or
its 
equivalent, and I'm sure that the soy flour - yeast - daphnia water
doesn't 
produce enough to cause any problems, if it produces any at all.

In my original post I said that the "how do I feed daphnia" question
always 
seemed to produce controversy.  Well, ...

Good luck!

Bill