multiple yeasts?

[blazingstar]

I am very interested in using multiple yeast strains to produce a beer. I heard that it is a common practice with some Belgian beer producers. I was wondering whether anyone knew of any info that could enlighten me. I was thinking about using a low attenuating yeast first at an elevated temp (75 degrees F). Then adding a higher attenuating yeast and droping the temp. I'm very interested in Belgian beers and have just created a very clean Belgian pale ale. Any help would be appreciated.

[BigWilley]

I would add both yeasts at the beggining so you get some influence from both. If you add one after 90% of the fermentation is over the second strain wont do much at all. Belgians are probably the best beers to blend yeast with so give it a shot and let us know what happens. I know when I talked to white labs about blending they told me you could get about 3 generations before one strain started to dominate. I imagine that if you blend a highly flocculent yeast with a poor flocculator you would have to be careful when harvesting to maintain the blend.

[blazingstar]

My thought was to add the second strain two days after pitching the first. First strain an ale yeast with low attenuation and high ester production. Second strain a lager yeast with higher attenuation and a clean profile. That way I get the ale characteristic from the first one combined with the dryer mellow profile from the second strain. I will only be doing it a 1/2 barrel batch, just as an experiment. Any advice would definately be appreciated.

[blazingstar]

I won't be harvesting the yeast, but flocculation is a good factor for me to consider.
thanks

[BigWilley]

I would think your best bet would be to call up your yeast supplier tell them what you want and find a single strain. After two days any good ale yeast will pretty much have the wort fermented out by the time the second yeast can get going, then if I understand you your going to add a lager strain which means you'd have to crash the beer down to lager temps and then add the lager strain. You had better pitch a good amount of an active lager strain to get it going. My thought is that its not worth the trouble except as an experiment, but if you want to do it make sure you get an ale yeast that will quit at low temps, as some will keep on churning even at lager temps.

[dick murton]

The big problem with multi strain yeasts is maintaining the right balance of the strains for pitch after pitch. If you don't, then you are highly likely to change the flavour profile of the beer. This was one of the reasons for the multitude of odd fermenting and cropping systems used in the UK, such as Yorkshire squares and the Burton Union system (and probably equally strange ones elsewhere originally) By cropping with a particular system, at a particular time, the dead yeast could be left behind and the suitable mix of yeasts cropped. The yeasts have to grow at suitable rates of course to maintain the yeast mix.

If you want to get characteristics from each strain reliably, it may prove necessary to pitch with fresh yeast each time, though it sounds as if this is exactly what you had in mind anyway. I have also used one yeast (mainly top cropping) for fermentation, filtered it, primed the beer and then added another highly sedimentary yeast prior to bottling, so the beer was bottle conditioned.

If you are adding yeast to already fermenting wort, you will either need to ensure the fresh yeast is fully oxygenated prior to addition, or aerate after addition, which may cause the first yeast to grow madly, and / or produce off flavours.

Good luck

[Tbrew]

For blending and ale and lager strain I think the best approach would be to ferment them separately and then blend them after primary fermentation or transfer a high Krausen beer into another during fermentation. The reasons are:

1) If you pitch one yeast in at start at say 15mill cells/ml and then pitch the second 2 days later the first strain should be in the neighborhood of 90 mill cells/mil while you would have to pitch ~6X the 1st strains initial amount for the second yeast to get close to equal.

2) Assuming you do not pre-oxygenate the second yeast it will have very low vitality and will not ferment well. If you re-oxygenate the fermenter you will have excessive yeast growth, foam and possible off flavors.

3) Most yeast flavor compounds are produced early in fermentation not late.

If you choose to ferment two strains initially together than make sure they play well together. Some lagers can have trouble at higher temperatures and some ales trouble at lower. This could quickly create an imbalance. I would look for strains that compliment in processing parameters but serve different roles (attenuation etc.).

FYI, Chris White from White labs gave a presentation on this last year and would be good for you to talk to.

Have fun!

[blazingstar]

Thanks all. What inspired me was Unibroue's Terrible. I heard that it has over 10 yeast strains used in its production. I've also heard that Duvel uses multiple yeast strains and different fermenting temps. Since I can't find any literature on it I'm using the old noggin to come up with some ideas. We'll see what happens. Thanks again.

Blazingstar

[dick murton]

Don't forget that they may never reculture their yeast from single cell culture slopes. Many of the traditional British ale brewers use nominally a single strain, but on DNA analysis they find a large number of strains. One I heard of recently uses nominally a two strain culture, but this actually consists of 23 + different identifiable DNA strains. Perhaps this is what Unibroue are referring to (?????)

[Tbrew]

Also most Belgian style breweries (including Unibroue) centrifuge their beer after fermentation and then dose "sugar"(maltose, candied, glucose etc.) along with a new high vitality bottle conditioning strain. This is why growing up yeast from the bottom of a Belgian "abbey/trappist style” beer will rarely produce the same beer. So as far as claims of a beer made with many types of yeast, you need to be sure they are referring to co-fermentation. If I sat at a bar and poured a Bud into a Bass I would have a multi strain fermented beer!

To follow up on Dick's thought on ale strains, some English strains have developed co-flocculence, where one strain would not flocculate without the other. In some cases this symbiotic nature can involve three strains of yeast! Isolated you might have one or two poorly performing yeasts. Not sure if these are being used with any regularity these days.

[Greenbrewmonkey]

Wow, I have heard (well, seen really) some really great posts on this thread. I have, over the years, somewhat specialized in top cropping "traditional" British strains, and in my current incarnation I focus on rustic French, and Belgian style ales. Again top cropping. In my experience all the above posts have been pretty much spot on with blending tips and advice. I have done the ale followed by lager thing, but only as a last resort, with, say a beer that just won't attenuate properly. Some of those Belgian strains can be finicky! Usually without aeration, or a huge highly active pitch. (For the reasons stated above) It can work, but the results are highly unpredictable. At best. At worst, imagine the worst yeast bite you've ever tasted. Then magnify it, then explain why you had to dump the batch! (Or serve the junk No fun either way.

I think Dick's last comment on the multiple strain use and copping rather than growing up from a single strain is very pertinent and an accurate statement for such breweries and strains in use. Many are very multiple, and the further technology advances for analysis, the more so they are revealed to be. This cannot easily be replicated by pitching two pure strains. And while I have heard (and spoken with) Chris White on the subject I find what he says to be a little off. In pitching two or so strains at once, I usually find one immediately dominant. In flavor profile, cropping, everything. From the very first batch. The reasons for this are eloquently stated at various spots above.
1) Yeasts have differing lags times and respond differently to differing initial fermentation temps, wort composition, aeration, etc. Given this, one yeast can easily get a leg up in a hurry.
2) Many of the more prominent flavor compounds are produced early in a fermentation. So see above.
3)Yeasts can flock differently at different rates and points during a fermentation, making cropping and repitching your blend challenging.

Hmmm. And all the other stuff said above as well.

Unless you can get your hands an "old" strain, and are prepared to treat it in a traditional manner, you may be in for an unpredictable / unrepeatable ride. When I speak to people about how to do this, I usually find them nodding OK, then saying "yeah, that would be nice, but..." and going back to their regular production habits. And hence not getting the results they might. So I also usually recommend just one good yeast to get the job done.

On a related note... While larger Belgian (& Belgian style) breweries will centrifuge and prime / re-yeast with (maybe) another strain, I would remind folks that this sort of thing is way out of reach of the smaller, farmhouse type producer. (Who can also make some fabulously complex beers.) I mean, think about it, have you priced a brewery sized centrifuge lately? And for a small producer keeping one old strain happy can be difficult enough without having to source / prop up another strain. It seems to make more sense that a small producer would re-yeast with the same strain. Heck, you've got lots of it around, and its highly viable. Most top cropping strains floc to the bottom of a bottle, to make matters even easier. And let's remember this bottle conditioning is re-fermentation. Using a lager strain means lager yeast by products. Sulfur, anyone? (To mention just one) In a Belgian ale, not so much so, no thank you. Also bottle re-fermentation rooms are often warm to HOT. Ever have the glycol go out on a lager only to have it soar to 75-80*F? Did it taste good? If so, you better play the numbers before your luck runs out! Speaking of numbers, check the bottled on date. The last bottle of Orval I drank was bottled two years previously (& was fabulous by the way!), which may explain why it wouldn't prop up all that well either!

There could be more, but this post is sooo long!
Hipa!
& much Aloha
Ron
(One small, Artisan, top cropping, bottle conditioning, rustic country ale type of brewer)

[Moonlight]

This can easily be done without a centrifuge. Just ferment with strain #1 and Krausen with strain #2. It will not matter if some of the first strain is still around-if your Krausen pitch is rip roaring while #1 is having the after Thanksgiving feast siesta. The inconvienent part is the logistics of having different yeasts healthy and vigorous on a production-type schedual. This is not rocket science, this is micro ecology. Separate yeasts by behavior-say settling speed (can you make one top crop, or harvest different layers), or ideal ferm temp(forcing one to consistently out pace the other when you wish it to. Be creative with the differences of the strains you have chosen.
When one looks at things done say in Belgium with yeasts, don't forget after a hundred years or more, a brewery can find the patterns that work-or more likely, the yeast find patterns that fit the humans needs.