Running Yeast Trials: Tips From the Pros
Yeast trials can mean a lot of different things, but ultimately it implies splitting a wort into at least two different fermentations. This is a great way to compare how the yeast will perform under different conditions, whether at the outset of fermentation, during active fermentation, or post-fermentation. We got recommendations for running yeast trials from two experts in the field.
Kara Taylor is the Technical Laboratory Manager at White Labs in San Diego, California
When we started our tasting room, I really didn’t understand how much of an influence a yeast strain could have on mouthfeel. Lagers brewed in an ale recipe still had a crisper mouthfeel. A panel of English strains showed how different creaminess can be influenced by strain.
My favorite story was when we were in Copenhagen and had provided brewers with a “wandering” pitch of yeast that travelled from brewery to brewery. Each brewery made a different style with the yeast, which was a farmhouse-style blend. We served all of the beers at a festival and it was funny because most of the beers were hard to tell apart. It was a great example of how a yeast-forward strain can dominate a beer, regardless of a style.
When running trials, there are a couple of different factors that we look at. Not only will we compare different strains but we will compare the same strain against itself . . . with the exact same conditions. This allows us to choose the most robust yeast to store in our bank. This may not be something homebrewers look at, but you may find that different generations of the same yeast can produce unique characterisitics in the final beer. We’re looking primarily for attenuation and flocculation characteristics when we perform these type of tests. When we compare different strains we will compare attenuation, flocculation, mouthfeel, as well as flavor and aroma characteristics.
I would recommend if you want to do some different variables such as pitch rates, trub levels, or fermentation temperatures, make sure that you focus enough time and thought so that you’re changing only one variable at a time. If you change the pitch rate between two fermenters while one fermenter has all the trub and the second fermenter has almost none, it’s hard to know what made an impact. Trials can be slow and tedious, but if you’re into the process the results can be very interesting.
Utilizing a control is something that is done in a scientific setting and may be difficult for homebrewers. You may think about comparing your beers to a commercial beer that is similar or a “standard” in that style. Trying to come up with your own homebrewed control when running yeast trials would not be a bad precedent to set either. I would say that doing a trial against a neutral strain such as WLP001 (California Ale) yeast is probably our most common, but we might be trying to compare yeasts that are more similar, like hazy strains that are popular these days.
We are lucky to have a brewery in- house and have the ability to do a lot of trials. For those, we usually round up a group of employees to help do some tasting notes. We will also run all of the beers through our analytical lab to help match up what we are smelling and tasting to the data. You can often perceive something as sweeter, but when you look at the data the beer actually has a lower gravity than the rest. Combining the tasting and analytical data can be very powerful when analyzing yeast strains. I highly recommend bringing friends or homebrew club members to a table for sensory analysis. Blind tastings are always fun!
Shaun Hill is the Founder and CEO of Hill Farmstead Brewery in Greensboro, Vermont
We are quite minimal with yeast “trials” but we do use many different strains, still. The most recent strain we brought in was the “H” Strain from a famed Czech lager producer. We have two yeast propagation vessels and will soon receive a new, trial fermenter. Hoping that the new fermenter will allow us the ability to experiment with some new yeast strains. I am also embarking on a new project that is guided toward further developing a proprietary yeast strain.
The two other biggest fermentation factors that we will tinker with is pitch rate and oxygenation rate. Not all yeast strains react in a similar fashion to these conditions. Learning a strain’s nuances and preferences helps us brew better beer.
When it comes to the wort we use for a trial, I think it depends upon the goals of that trial — but I believe that a consistently made wort that is simple and repeatable is best. For us, we would use a 12 °Plato (1.048 SG) wort with moderate bitterness. And for tasting, get plenty of crackers. Blind tastings in a well ventilated room . . . that’s how we do it here at Hill Farmstead.
Tamara Logsdon is the Quality Control Lab Coordinator and Brand Manager at Wyeast Laboratories in Hood River, Oregon
Yeast trials are small-scale fermentations set up to experiment with different variables, so that any parameter of the brewing process can be adjusted, measured, manipulated, etc. Like all good science, trials give you the ability to set up a control, which is a standard for comparison between known and unknown outcomes. For example, if you were interested in adjusting your favorite saison recipe, your control should be your original recipe. It’s familiar, you know what to expect when you brew it, how it should taste.
You should have detailed notes on your brewing process so that the final beer is reliably consistent. Your variables could be a change in yeast strain, how the strain is expressed on different mash methods, using a harvested pitch compared to a fresh one, just to name a few. Maybe you want to troubleshoot an issue you’re having such as stuck fermentation or an off-flavor in your beer. Variables are limitless! Trials will help you gain a better understanding of the intricacies of brewing and how a specific parameter can influence the final outcome of your beer.
Homebrewers mainly focus on yeast strain trials. There are several fermentation dynamics you can trial with the same strain (temperature, pitch rate, pressure, to name a few). I think there are no limits or requirements other than what you want to understand better or control with more intention. Use a simple, low-gravity, neutral recipe that will allow any nuances to be identified. If your goals are specific to a recipe you already brew, perfect the details and use that as your standard.
When I started working on sensory analysis, it was very informal. I would ask as many questions as possible and describe what I was tasting in a beer to colleagues or friends in the industry and listen to their feedback and interpretations until I understood how to identify and use sensory vernacular. Whether a sensory evaluation was being done on a sample in the lab, or I was at a local brewery, I asked questions all the time. Your sense of smell and taste are two of your most powerful tools – it truly takes practice to calibrate them!
