Differnt Strains of Yease

[coop]

Has any one ever mixed two different strains of Yeast? If so what were your results. Coop

[Charles@AEppelTreow]

I use three strains in sequence for in-bottle sparkling cider/perry. A slow fermenter with really good aromatics, followed by another that mops up any residual sugar and then an encapsuled yeast in tirage to speed riddling.

I've also tried the chr hansen non-sacchromyces blends. 2-3 dry yeasts blended to have different pitching rates, and so simulate a native-yeast succession. The results with a dessert cultivar blend of apples wasn't notable.

[JohninWV]

Not to put out Todd's business, but he may have some input.

http://adiforums.com/index.php?showtopic=1550&view=findpost&p=8795

[poca]

I switched to a different strain a few weeks ago bc i liked the flavor profile of the new yeast better. Realized I wasn't getting full attenuation sfter s few brews though. So a did half and half new and old. Full attenuation and nice profile.

Its my understanding that there can be a more dominant strain that would take over the fermentation. At least with beer yeast.

[Denver Distiller]

Not to put out Todd's business, but he may have some input.

http://adiforums.com/index.php?showtopic=1550&view=findpost&p=8795

Not much to add here, save to reiterate that yes, indeed, we use at least two strains on every line spirit we make.

IMHO, you need to have your ducks in a row to do it.

[JohnD]

We've gotten some really nice results with a combination of wine or brewing yeast followed by distiller's yeast. The flavor profiles are excellent but Denver's right, you have to have your stuff together to maintain consistency.

[Chris Martin]

We've gotten some really nice results with a combination of wine or brewing yeast followed by distiller's yeast. The flavor profiles are excellent but Denver's right, you have to have your stuff together to maintain consistency.

JohnD & Todd, what in particular should I watch out for re: maintaining consistency? Thanks!

[Chris Martin]

Has any one ever mixed two different strains of Yeast? If so what were your results. Coop

Coop,

If you can get your hands on it , you can find an interesting Japanese study on this in Chapters 15 & 16 of the 2008 Worldwide Distilled Spirits Conference book titled Production, Technology and Innovation.

In a nutshell, use of brewer's yeast with distiller's yeast yielded a more "complicated" spirit, but unfortunately at the expense of "estery" qualities. Of the brewer's yeasts tested, the most distinctive spirit was found specifically with dry ale yeast (supplied by Lallemand and Fermentis).

The reason for the lack of esters with the dry ale yeast was explained this way:

The first is the growth phase of the fermentation. Dry ale yeast grew much more, therefore this high growth of yeast could produce high fusel alcohols. On the other hand, dry ale yeast produced less esters because the yeast would be propagated under aerobic conditions (Boulton and Quain, 2001). The second is the death phase. The autolysis of yeast could not proceed because of the survival of the yeast. Thus, the degradation of intracellular components would be lower, and the amounts of long chain fatty acid esters were in consequence less.

So, it was suggested that the estery quality could be improved by the following at the growth phase:

The first method is changing the pitching rate to be lower than usual. It will prevent a rapid depletion of the acetyl-CoA (Boulton and Quain, 2001). The second is to propagate again under anaerobic conditions. This would decrease unsaturated fatty acids contents of yeast’s membrane at the beginning of the growth phase (Boulton and Quain, 2001). The third is the use of clear wort. The use of clear wort is the most effective for increasing esters. Clear wort means lower contents of lipids, and can be obtained by less raking in mashing (Boulton and Quain, 2001).

And, at the death phase...

We suggest three methods to increase the autolysis of yeast at the death phase. The first method is expansion of the fermentation period, since the stained cell ratio of yeast at the end of fermentation is low. Thus, the yeast will be dead, and the degradation of intracellular components could be higher. However, there is a possibility that excessive degradation of the wash would arise in the case of overly long fermentations. The second method is to raise the maximum fermentation temperature by raising the initial fermentation temperature. However, one must take care to prevent sugars remaining in the wash at the end, as the autolysis of yeast at high temperatures may occur before all sugars have been consumed. The third method is to promote the fermentation of lactic acid in the latter phase. If conditions are set up, pH would fall due to the increased lactic acid, and the autolysis of yeast would be promoted as a result.

Also, some interesting info in Chapter 14 of the 2004 edition, Tradition and Innovation.

[JohnD]

Hey Chris, sorry for the late response. For some reason the forum stopped auto-emailing me when there's a response to one of these threads.

Co-cultures are complicated environments. Your yeasts will produce different compounds in different environments. If you stress one yeast by putting it in later in the fermentation (low free nitrogen, low glucose, etc) it may produce some really interesting flavors, and very little ethanol, but add interesting flavor notes to your finished spirit. Timing your innoculations can be difficult if you don't have good analytical. It's rarely as simple as; wait until day 3, add second yeast. It's usually better to track something like brix and pH and pitch at a specific point in the process. If you don't keep track of such things and pitch consistently using some analytical measure, your product will be subject to variation.

[Chris Martin]

Makes sense... thanks for that John.