I’ve been talking a fair bit about yeast blending in brewing with fellow brewers recently. Brewers reaching out to me on the back of my article on wine yeast and brewing being shared on the MTF (Milk The Funk) Facebook group.
It’s a subject I plan to explore more now I’ve access to a pilot system. This article is meant as a short introduction to the subject of yeast blending in brewing, with co-fermentation information covered as well.
As I do more experiments, I hope to share some of my findings. So, build a little repository of knowledge for myself, as well as for other people to access, if they find the subject interesting too. It will be slow moving project as it’ll fit around my other work however, we all have to start somewhere, right?
Yeast Blending in Brewing – What’s The Appeal?
More and more yeast strains are becoming available to commercial brewers. The whole Norwegian Kevik yeast discovery by the outside brewing world a few years ago, with many breweries now having a Kveik beer in their core range. Is an example of new yeasts being used in commercial breweries.
Many yeast strains are single cultures with well-known traits. If a brewer were to blend yeasts, it gives them the opportunity to create unique beer profiles and offer “something different”. As craft breweries continue to pop up, with competition becoming fiercer, the need to offer something new, fresh and appealing is attractive to a brewer.
Possibilities are endless so, the chances of creating something unique is easily possible plus, the journey can be fun to boot. When it comes to blending yeasts strains there are several approaches and the benefits to consider including:
New flavor profiles
With experimentation and tweaking new unique flavor and sensory profiles can be created through combining different yeast strains.
Take advantage of different yeast profiles
For example, you can combine yeasts to hit desired beer recipe parameters like target FG and flavor profile not possible with a single strain.
You can combine an alcohol tolerant strain with one which is less tolerant but has a flavor profile you like. Furthermore, different yeasts have their own performance expectations like sugar utilization, temperature tolerance and flocculation. Combining yeasts could help condition your beer.
Combing yeast already in-house can create a new beer profile without having to bring or buy another yeast into the brewery.
Standing Out from The Crowd – Yeast Blending in Brewing
As we said above, as the craft beer market becomes fiercer, the need to “stand out” becomes stronger. Creating something new by blending yeasts could catch the imagination of the public and create a buzz for your brewery.
The Stages of Fermentation – Yeast Blending in Brewing
Before we moving on, it makes sense to go over the stages of fermentation, please read my in-depth article by clicking the link. However, I’ll add a quick recap below.
Nothing appears to be happening, as there’s no visible activity. However, the yeast is absorbing the oxygen in the wort (producing sterols), which is crucial to reproduction, healthy growth and fermentation. The yeast is getting ready to do its thing.
After 2 to 48 hours, you should see active fermentation, depending on yeast strain. The yeast cell count increases fast, as it consumes the sugar made on brew day.
Furthermore, CO2 is produced and a layer of foam called the krausen forms. Ethanol and flavor compounds are being produced. In the first 72 hours most of the flavor compounds are formed in most styles of beer (again depending on the yeast).
During this phase beer is still considered “green” but begins to condition. The yeast begins to absorb diacetyl made during fermentation. Hydrogen sulfide escapes the FV (fermentation vessel) and the foam layer dissipated with the yeast beginning to flocculate and settle out.
Once the beer has reached terminal gravity and in accepted parameters such as the VDK (vicinal diketones) numbers are good. You chill the beer and allow it to mature.
During this time the beer becomes clearer, haze forming protein precipitate and the beer smooths out. Plus, there’s a reduction in sulfur compounds, diacetyl and acetaldehyde.
What We Need to Consider When Yeast Blending in Brewing
So, after a little crash course in the stages of fermentation. Let’s back to the key elements to consider when blending yeast.
When combining yeast strains, you can’t inoculate your wort without careful thought and consideration. There are several elements a brewer needs to consider when blending.
Lag phase – Some yeasts may have longer lag phase than others. It might allow one yeast to dominate over another.
What sugars do the yeasts consume? – Not all yeasts are created equal. Need to understand the sugar spectrum each yeast can ferment and how they might complement each other.
Flocculation – Strains vary in how the flocculate with some being more flocculation than others. You need to think how different strains might interact.
Flavor profiles – Will different yeasts complement each other. For example, will a yeast known to promote banana esters and aromas work well with a yeast which sours?
Kill Factor – We spoke about the kill factor in my wine yeast article. Some yeasts have the ability to kill off other yeasts, you need to consider this if co-pitching. We will explain in more detail below.
When to Pitch – Do you add both yeasts at first pitch or wait and add a second yeast later (co-pitch) either later in primary or during secondary fermentation?
A Major Disadvantage – Predictability
I was speaking with one of my brewing buddies who was talking about having a blended yeast beer in their core range. The main concern is it’s hard to predict how the yeast will work when re-pitched.
One strain may become more dominant over subsequent generations making consistency a challenge or near impossible. It might mean yeast blending is a one-time deal with single brew and starting fresh with the next batch.
When you mix strains, the outcome is always hard to predict and currently there’s not much literature on the subject either. There’s a lot of trial and error when blending, that’s why having the pilot system to trial on is important to me.
I need to do many trials recording as much data as possible. Learning from each trial to understand yeast interactions over time. The fun is learning with each batch and tweaking methodology to brew beer with profiles I’m aiming for.
Working With Wine Yeasts in Beer – Yeast Blending in Brewing
As I say, I’ve written a lot on this subject in the wine yeast article. However, it seems prudent to discuss some of the main themes here.
Wine Yeasts Don’t Ferment Many Sugars in Beer Wort
Wine yeast might not ferment maltose and maltotriose, the main sugars in wort. They will ferment other sugars and you’ll need to add a beer yeast to ferment the beer out to your target gravity.
Hence co-pitching. The other option is to use an enzyme to break down the more complex sugars into simple ones the wine yeast can ferment.
As we said before, we need to understand if a yeast has the kill factor. Many wine yeasts have it. If they do then the beer yeast will not ferment if either pitched at the same time or added later on. In this case you’ll need to pitch the beer yeast first and the wine yeast after or…
Split the batch say 70% beer for the beer yeast and 30% for the wine yeast. Then use an enzymes like Convertase AG-300 to convert the sugars into simple sugars so, the wine yeast can ferment the beer wort fully. Once both yeasts have finished you can blend them at a later date.
POF+ and POF-
Wine yeasts are most often POF+ (phenol off-flavors), meaning went fermented in beer wort they create undesirable phenolics not suited to beer. There are some POF- wine yeasts more suited to beer making and they are listed in the other article. Still, little is known on the subject and more researched is needed.
Other Yeasts to Consider – Beyond Brewing Yeasts
I’ve spoken a lot about Milk the Funk (MTF) recently, they have their own wiki and it’s a brilliant resource for learning to use non-brewing yeasts in beer making. Please click here to go to the main page of MTF.
There are many yeasts discussed on the site, including Lachancea thermotolerans of which Levilia Alcolmeno has been trialed for beer production. And has now become commercially available as Fermo Acid brew by AEB. It ferments the glucose present in wort to lactic acid.
It’s a viable alternative to produce consistent sour beers in the fermentation vessel. As glucose represents roughly 14% of the sugar make-up of wort, you’ll need to co-pitch a beer yeast to hit terminal gravity. Being able to create sour beers in FV rather than take up kettle time for souring certainly appeals to brewers.
Brewers are looking at other non-beer yeast strains now with S.kudriavzevii and Torulaspora delbrueckii seemingly having potential. Furthermore, there’s Brettanomyces plus bacteria (beyond lactobacillus), which have been collected from local microflora and been experimented with, also showing promising results.
There’s a whole world of exploration out there for brewers to discover. As we learn of the new sensory and functional contributions these yeasts and bacteria can potentially make. However, one note of caution…
You need to be careful of cross contamination. You need to ensure if you’re bringing anything new into a brewery you have proper measures in place to prevents cross contamination.
In some breweries for example; their sour beer program is completely separate from the normal production facility with its own packaging line.
Yeast Blending in Brewing and Co-Fermentation Pitching – Conclusions
I hope it comes across yeast blending in brewing is a subject I’m passionate about BUT, also cautious of too (cross contamination). There is so much potential in blending and co-pitching for creating unique sensory profiles as well as practical and functional rewards.
As brewing continues to evolve with craft beer drinkers becoming more adventurous, there’s certainly room for experiment as there’s audience willing to try what’s produced. As the heavy hopped IPA’s, pastry stout and heavily adjunct beers become the norm; is yeast blending the new frontier of craft brewing? I guess we will soon find out…
If you have experience with yeast blending, using wine yeasts or co-pitching please feel free to comment below or send me a message. My email is: firstname.lastname@example.org
Or you scan the QR code below of your preferred and add me there too. Thanks for reading and happy brewing.