Two yeasts - other questions

From my understanding, you have it about right. The wild yeast is more sensitive to the sulfite where the nice domestic yeast that is tolerant of it.

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.

At least that is how I interpret what is going on.

Ray

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

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.

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.

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 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

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:

multiple

|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

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

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

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