Ray Calvert wrote:

If you pitch two tolerant yeasts at the same time they will both
develop
colonies and each will devour as much sugar as it can, competing with
the
other as each yeast cell in each colony competes with each other
yeast cell.
They really do not care what yeast cell they are competing with.
They are
not prejudiced. They are just hungry. If you mix types, you may be
mixing
character of wine. That is all.

I think it's a little more complicated than that.


"Rob" wrote

Wine yeast is pitched onto a must, which of course has some wild
yeast
in it as a matter of course. We sulphite the must, which inhibits
the
wild yeast, allowing the pitched yeast to multiply rapidly and
overwhelm the wild yeast by numbers.

If the wild yeast isn't resistant to SO2 also. The SO2 can inhibit the
cultured yeast also. My understanding is SO2 is harmful to all yeast
but the "resistant" yeasts can neutralize the SO2 but may still be
stressed by it.

How do yeasts create environments that "kill off" other yeasts, or
does
it just slow them down?

It can do both. Some yeast strains will up take certain nutrients very
quickly and store them for later use. This can cause a limiting factor
for other strains which may slow their reproduction.

There are also strains that produce a "killer factor". I believe this
is a peptide that disrupts critical cell function. Yeast strains can
produce this killer factor, can be resistant to it but not produce it,
or can be sensitive to it.

You also have to take into account speed of reproduction. Even what I
would consider a small difference in reproduction speed can have a
significant effect on which yeast becomes dominant.

Some yeast strains are more sensitive to lack of certain nutrients. If
the must is low in those nutrients, another yeast may be able to
compensate faster and become the dominant strain.

There are a whole host of chemicals yeast can produce that can be
inhibitory to other organisms, even other yeast strains.


Are there wine yeasts that are compatible with
each other? What exactly happens if you pitch two wine yeasts? Is
there one wine yeast which is the king - outcompetes them all?

I think that's the problem, no one really knows. Certain yeast strains
are very strong and will probably take over, but I think in general
it's too complex to really figure out exactly how each yeast will react
and it may even change from one must to another.


Andy

I kind of agree however it seems to me, not through experience just
intelectual persuit, that all the yeasts will respond to the
environment but probably the one most suited to the conditions will
predominate. If this is so then there will probably be some wild yeast
activity but it'll be supressed by the sulfite. If there are multiple
yeasts adapted to a sulfited must then the faster growing yeast will
have the greatest influence in the beginning and the most alcohol
tolerant yeast will take over towards the end.

Chris

I kind of agree however it seems to me, not through experience just
intelectual persuit, that all the yeasts will respond to the
environment but probably the one most suited to the conditions will
predominate. If this is so then there will probably be some wild yeast
activity but it'll be supressed by the sulfite. If there are multiple
yeasts adapted to a sulfited must then the faster growing yeast will
have the greatest influence in the beginning and the most alcohol
tolerant yeast will take over towards the end.

Chris

That makes sense, and in fact I made a zinfandel with three different
strains, mixing them following primary, just to judge what they did to
the wine - great experiment, and were I to have enough equipment,
I'd've kept them separate all the way through to blend them. Ah, well.
But it's an experiment I encourage others to do - I concluded there
was more variability in yeast than which oak toast you use, or where
the barrel staves were grown.

And Chris, I agree with the outcompete theory. If one strain (say
sulphite resistant) has a 100x reproduction factor over another (wild
yeast), it certainly will dominate.

So there's no equivalent of "vines-to-wines" for yeast, huh?

Thanks, guys. Very interesting. Love this newsgroup.

Rob



Ray Calvert wrote:
I agree with both Andy and Chris. I did over simplify. One of the
yeast
will provably have a slight or a not so slight advantage and that
yeast will
dominate. If you really want the character of two different yeasts
blended
then you should make two different wines, one with each, and then
blend
them. If you try to blend the yeast, you will probably end up with
one or
the other.

Ray

"Chris" wrote in message
oups.com...
I kind of agree however it seems to me, not through experience just
intelectual persuit, that all the yeasts will respond to the
environment but probably the one most suited to the conditions will
predominate. If this is so then there will probably be some wild
yeast
activity but it'll be supressed by the sulfite. If there are
multiple
yeasts adapted to a sulfited must then the faster growing yeast
will
have the greatest influence in the beginning and the most alcohol
tolerant yeast will take over towards the end.

Chris

|If the wild yeast isn't resistant to SO2 also. The SO2 can inhibit the
|cultured yeast also. My understanding is SO2 is harmful to all yeast
|but the "resistant" yeasts can neutralize the SO2 but may still be
|stressed by it.

I have read in many places that wine growers add sulphite right at
the crush. Cultured yeasts may be stressed by the sulphite but it
seems to be common practice to add it to inhibit wild yeasts.

Don

If you pitch two tolerant yeasts at the same time they will both develop
colonies and each will devour as much sugar as it can, competing with the
other as each yeast cell in each colony competes with each other yeast cell.
They really do not care what yeast cell they are competing with. They are
not prejudiced. They are just hungry. If you mix types, you may be mixing
character of wine. That is all.

So let's go back to my original posting where I was thinking about
adding EC-1118 after a full fermentation with D-47. The purpose of
the 1118 is to ensure it is fermented down to dryness due to it being
an aggressive and very tolerant yeast. In light of this discussion
would you not think that there will be no adverse affects. That the
character of the wine will be that of the D-47 and that adding the
1118 will just have it attempt to finish fermenting whatever the D-47
did not finish ie. residual sugar.

I'm thinking if the D-47 left off a 0.998 that the 1118 might take
it down to 0.997 or 0.996. Completely dry with no chance of later
fizziness. I'm kinda rushing this wine doing it pretty much by the
instructions because I'm out. The only change is the use of D-47.
And in this situation I think there's a good chance of minor bottle
fermentation, thus the 1118.

Don
Don

If you pitch two tolerant yeasts at the same time they will both develop
colonies and each will devour as much sugar as it can, competing with the
other as each yeast cell in each colony competes with each other yeast cell.
They really do not care what yeast cell they are competing with. They are
not prejudiced. They are just hungry. If you mix types, you may be mixing
character of wine. That is all.

So let's go back to my original posting where I was thinking about
adding EC-1118 after a full fermentation with D-47. The purpose of
the 1118 is to ensure it is fermented down to dryness due to it being
an aggressive and very tolerant yeast. In light of this discussion
would you not think that there will be no adverse affects. That the
character of the wine will be that of the D-47 and that adding the
1118 will just have it attempt to finish fermenting whatever the D-47
did not finish ie. residual sugar.

I'm thinking if the D-47 left off a 0.998 that the 1118 might take
it down to 0.997 or 0.996. Completely dry with no chance of later
fizziness. I'm kinda rushing this wine doing it pretty much by the
instructions because I'm out. The only change is the use of D-47.
And in this situation I think there's a good chance of minor bottle
fermentation, thus the 1118.

Don
Don

Don S wrote:
|If the wild yeast isn't resistant to SO2 also. The SO2 can inhibit
the
|cultured yeast also. My understanding is SO2 is harmful to all yeast
|but the "resistant" yeasts can neutralize the SO2 but may still be
|stressed by it.

I have read in many places that wine growers add sulphite right at
the crush. Cultured yeasts may be stressed by the sulphite but it
seems to be common practice to add it to inhibit wild yeasts.

Don

While it may be common practice, it's not universal and many wine
makers are going the other way. No initial SO2 addition if the fruit is
sound and even encourage a little wild yeast growth before pitching the
cultured yeast. It's supposed to create some complexity in the wine.

The no initial SO2 will also eliminate one stress factor for your
cultured yeast. Stressed out yeast tend to produce more unwanted
by-products.

Andy

Don S wrote:
|If the wild yeast isn't resistant to SO2 also. The SO2 can inhibit
the
|cultured yeast also. My understanding is SO2 is harmful to all yeast
|but the "resistant" yeasts can neutralize the SO2 but may still be
|stressed by it.

I have read in many places that wine growers add sulphite right at
the crush. Cultured yeasts may be stressed by the sulphite but it
seems to be common practice to add it to inhibit wild yeasts.

Don

While it may be common practice, it's not universal and many wine
makers are going the other way. No initial SO2 addition if the fruit is
sound and even encourage a little wild yeast growth before pitching the
cultured yeast. It's supposed to create some complexity in the wine.

The no initial SO2 will also eliminate one stress factor for your
cultured yeast. Stressed out yeast tend to produce more unwanted
by-products.

Andy

Don S wrote:


So let's go back to my original posting where I was thinking about
adding EC-1118 after a full fermentation with D-47. The purpose of
the 1118 is to ensure it is fermented down to dryness due to it being

an aggressive and very tolerant yeast. In light of this discussion
would you not think that there will be no adverse affects. That the
character of the wine will be that of the D-47 and that adding the
1118 will just have it attempt to finish fermenting whatever the D-47

did not finish ie. residual sugar.

I'm thinking if the D-47 left off a 0.998 that the 1118 might take
it down to 0.997 or 0.996. Completely dry with no chance of later
fizziness. I'm kinda rushing this wine doing it pretty much by the
instructions because I'm out. The only change is the use of D-47.
And in this situation I think there's a good chance of minor bottle
fermentation, thus the 1118.

Don
Don

You can maybe do this without any adverse effects, but I still don't
understand why you think this is necessary? I've done both juice and
kit whites with D47 and never had any issues with stuck fermentation.
It's a great yeast for whites and should be happy with PAs up to 14,
maybe even 15%.

Also, that ending gravity you mention looks high to me. All the dry kit
whites I've done to this point ended at 0.992 or less, one Chardonnay
even dropped under 0.990.

More likely that not, if you add EC1118 that late in the ferment, it
will just die off. And I would be worried that adding a new yeast
strain could actually slow down the first yeast, to the point of
sticking.

Pp

I'm not sure the 1118 will even start if you add it straight to all
that alcohol. If you really want to do this, maybe get it acclimated
to alcohol first by pulling off a bottles worth and watering it by half
and adding sugar. Once it takes off you can add it back in.

I use both 1118 and D47 and don't have issues getting D47 to dry. You
may want to warm the wine up and rack it to see if it restarts. I
would think you are better off measuring RS with Clinitest rather than
relying on a hydrometer as an FYI.

Joe

I'm not sure the 1118 will even start if you add it straight to all
that alcohol. If you really want to do this, maybe get it acclimated
to alcohol first by pulling off a bottles worth and watering it by half
and adding sugar. Once it takes off you can add it back in.

I use both 1118 and D47 and don't have issues getting D47 to dry. You
may want to warm the wine up and rack it to see if it restarts. I
would think you are better off measuring RS with Clinitest rather than
relying on a hydrometer as an FYI.

Joe