I've been told this is nasty, what do YOU know?

--
billb
Since time immemorial, the powerful have used religion to distract
the oppressed, to encourage them to focus on the next world so that
they will acquiesce to the injustices of this world. If you would
have your slaves remain docile, teach them hymns.

Yeast can undergo different changes, which can affect fermentation, in
response to their environment. They can undergo physiological changes
and they can undergo mutational or genoimic changes.

Researchers consider any change that undergoes the yeast population
after about 20 generations to be a physiiological change. That is the
yeast are still the same strain, they just have turned on different
genes and re doing differnet things. As a winemaker you cannot really
do anythign about that...but these fchanges are minor and not a big
problem.

Changes that undergo a yeast population after about 200 generations are
considered to be mutational, that is the yeasts DNA has changes and
they have become a different strain. These changes can have
significant effects on the fermentation or they may be benign.

Now two things, first wine yeast are pretty much optimized to work in
wine, so there is no real change to adapt to. So they do not need to
change so much. (although they still do change, but that is a differnt
issue called genetic drift). Second, yeast manufactures produce yeast
from stocks that are created froma progenitor cell. So they are in
theory identical from batch to batch. So if you jsut use fresh yeast,
you will be using the same yeast every time. This issue is only really
a concern for people that culture their own yeast, or those that seed
their vines with yeast (from pomace) and let their wine undergo
spontaneous fermentaion.

wow, how complicated!

--
billb
Since time immemorial, the powerful have used religion to distract
the oppressed, to encourage them to focus on the next world so that
they will acquiesce to the injustices of this world. If you would
have your slaves remain docile, teach them hymns.
"Droopy" > wrote in message
oups.com...
> Yeast can undergo different changes, which can affect fermentation,
in
> response to their environment. They can undergo physiological
changes
> and they can undergo mutational or genoimic changes.
>
> Researchers consider any change that undergoes the yeast population
> after about 20 generations to be a physiiological change. That is
the
> yeast are still the same strain, they just have turned on different
> genes and re doing differnet things. As a winemaker you cannot
really
> do anythign about that...but these fchanges are minor and not a big
> problem.
>
> Changes that undergo a yeast population after about 200 generations
are
> considered to be mutational, that is the yeasts DNA has changes and
> they have become a different strain. These changes can have
> significant effects on the fermentation or they may be benign.
>
> Now two things, first wine yeast are pretty much optimized to work
in
> wine, so there is no real change to adapt to. So they do not need
to
> change so much. (although they still do change, but that is a
differnt
> issue called genetic drift). Second, yeast manufactures produce
yeast
> from stocks that are created froma progenitor cell. So they are in
> theory identical from batch to batch. So if you jsut use fresh
yeast,
> you will be using the same yeast every time. This issue is only
really
> a concern for people that culture their own yeast, or those that
seed
> their vines with yeast (from pomace) and let their wine undergo
> spontaneous fermentaion.
>

Yeah, you have to go to school for 20 years to really understand it.

does yeast ever mutate to the point that it stops making ethanol and
makes harmful things?

--
billb
Since time immemorial, the powerful have used religion to distract
the oppressed, to encourage them to focus on the next world so that
they will acquiesce to the injustices of this world. If you would
have your slaves remain docile, teach them hymns.
"Droopy" > wrote in message
oups.com...
> Yeah, you have to go to school for 20 years to really understand
it.
>

On Thu, 22 Sep 2005, billb wrote:

> does yeast ever mutate to the point that it stops making ethanol and
> makes harmful things?

Yeast can mutate so much that they cannaot survive in the condition
encountered in a must or wine but that isn't something you will ever
encounter if you are following normal winemaking procedures. Yeast are
distant relatives of humans and many things that would make humans sick
would also kill yeast. Yeast won't make anything that will kill you
unless you are foolish and drink too much.

Warren Place

well I wonder about that because, as I've stated publicly here, I've
been using the same yeast for over a year, and it seems to still be
working. in fact, I've got excess yeast in the process and I mix
that with flour for bread or just throw it out.

but now I'm wondering if the yeast I started with a year ago is the
same as the yeast I have now???

to allay this fear, I've spent the whopping total of 2 dollars and 25
cents on new yeast and a package of yeast nutrient to add to the mix
on the theory that the nutrient will allow the yeast to remain in its
current form for a while.

who knows? lord knows I don't.

--
billb
Since time immemorial, the powerful have used religion to distract
the oppressed, to encourage them to focus on the next world so that
they will acquiesce to the injustices of this world. If you would
have your slaves remain docile, teach them hymns.
"Warren Place" > wrote in message
s.edu...
> On Thu, 22 Sep 2005, billb wrote:
>
> > does yeast ever mutate to the point that it stops making ethanol
and
> > makes harmful things?
>
> Yeast can mutate so much that they cannaot survive in the condition
> encountered in a must or wine but that isn't something you will
ever
> encounter if you are following normal winemaking procedures. Yeast
are
> distant relatives of humans and many things that would make humans
sick
> would also kill yeast. Yeast won't make anything that will kill
you
> unless you are foolish and drink too much.
>
> Warren Place