Tasting and Making Thiols

In early 2023, Laura and Allison teamed up with Lindsay Barr of DraughtLab to design some experiments in order to see how Thiolized yeast impacts beer flavor and consumer preference. The main hypotheses were:

• Thiolized yeast brings more tropical flavor

• People like thiols

• Dry hopping changes thiol perception

• Positive correlation with shelf life

We’ll examine all of these below.

One particular tropical flavor is a compound we’ve spent a lot of time discussing: 3SH (3‑sulfanyl-1-hexanol). While our understanding of 3SH in beer is relatively new, this compound was first identified in passion fruit, and later identified in sauvignon blanc wine as well as other fruits.

The key here is the human nose — tasters noticed a similar aromatic quality to all of these different fruits and beverages, and by digging for the source of this common link, researchers were able to identify the common thiol compound, 3SH. This research is ongoing, and we’ve only brushed the surface of understanding the role of 3SH in beer.

Knowing that Thiolized yeast is capable of generating thiols like 3SH, we were certain that using Thiolized yeast in our beer samples would bring more tropical flavor. When comparing two beers from the same batch — one half fermented with a non-Thiolized control yeast and the other fermented with Thiolized yeast, our sensory panel picked up significantly more tropical and citrus notes.

We also had some help from our friends at Half Acre Beer Co. in Chicago — we enjoy working with them because they also geek out on the science and are always up for a little experimentation. They produced a batch of their Pony Pils using Lunar Crush, a Thiolized lager yeast, which we used to compare to their standard Pony Pils. We first tested this concept at the 2023 NY State Craft Brewers Conference. Tasters found significantly higher citrus, fruity, and tropical flavors in the Thiolized Pony Pils.

Whether consumers enjoy a beer is possibly the most important thing for a brewer to consider. After all, why make a beer if nobody likes it? We have been experimenting with thiols for a while now, and have found that overall most people tend to like them… but anecdotal evidence isn’t hard data, so we also included a hedonic test to see how our samples scored.

When comparing the Pony Pils vs. Thiolized Pony Pils at CBC in Nashville, we didn’t see a dramatic difference in the ​“liking score” from one to the other. For both samples most tasters scored their degree of enjoyment somewhere in the middle, though we saw more polarizing results with the Thiolized sample. The number of tasters that increased their liking score was higher (see shift from score of 5 – 7 to 6 – 8), but also a smaller number of tasters lowered their liking score (1 – 2). 

We are still interested in determining whether there is a difference in consumer perception of 3SH that drives this polarization, where the majority of tasters perceive tropical aromas, yet there are some tasters that tend to perceive general sulfur notes. Compare this to how some members of a sensory panel may describe acetaldehyde as being like a ripe green apple, while others may experience it as raw pumpkin or fresh paint — people experience flavors differently. 

We also asked for hedonic scores with a dry-hopped IPA brewed with Thiolized yeast from Bearded Iris Brewing in Nashville, and the scores were even higher and slightly less polarizing than the results of the two versions of Pony Pils.

We think this underscores a really important principle of beer recipe design: you have to take every element of the recipe into account when layering in thiols. The thiols in the Pony Pils were intense, but with little else to meld and blend flavor, seemed to become less desirable for some drinkers. However, tasters were much more interested in the flavor of the thiols blending with the dry hops in the Bearded Iris beer. 

The research around dry hopping and thiols is ongoing, and complicated. We encourage you to consider a few factors when building recipes:

1. Odor activity value: how much of the aroma compound is present above the odor threshold? How much do you need for it to become impactful in your beer?

2. Masking/synergy: do you alter the perception of thiols with dry hopping, or are the thiols being masked by hop intensity? Do your hops and thiols create a complementary aroma profile?

3. Aroma quality: is there a point where more is not better? 

Above all, what you should strive for is balance. Build hop and thiol aromas together until you find the levels that you like. 

The team at Deschutes Brewery ran a shelf life study using dry-hopped Thiolized beer in an effort to discover whether the presence of thiols had any impact on the perception of oxidation, hop flavor, and fruit flavor. What they found was that when compared to a fresh sample, dry-hopped Thiolized beer maintained its stability after two months. It decreased in sulfur character after 0 – 1 month (from BBT to 1‑month-old cans). It increased in fruit scoring from 0 – 2 months (from BBT to 2‑month-old cans).

Overall, this is one shelf life study to show how thiol compounds alter the typical shelf life of a beer. These tend to improve over time. Our customers have shared this anecdotally, and have been pleasantly surprised at how well Thiolized beers have held on. We will continue to investigate this through shelf life analysis and would love to hear about the shelf life studies you have underway.

When brewing with Thiolized yeast, the primary flavors of thiols tend to dominate, which can in turn reduce the perception of cereal and bready aromas, as we saw in the Pony Pils comparison. Strong dry hop aromas can create entirely new combinations of flavors that many tasters will find pleasant, and while thiols overall can be polarizing, we have seen results that would suggest most people really like the tropical fruit flavors that thiols bring. 

We suggest taking these experiments back to your own breweries and trying some split batch fermentations to help you answer a few key questions:

1. What are thiols?
   Compare a control batch of a lager or blonde ale with a test batch of the same recipe fermented with Thiolized yeast. Use hedonic testing and/or a ​“check all that apply” (CATA) method to determine how much your tasters like the Thiolized sample and to establish common thiol flavor descriptors.

2. How are thiols impacted by dry hopping?
   Now compare a Thiolized lager/blonde with a dry-hopped version of the same. Use descriptive analysis and blending exercises to observe the differences in thiol sensory with and without the presence of dry hopping. By blending you can determine the ideal ratio to achieve the best thiol/hop balance.

3. Do thiols work in my recipe?
   Make a classic NEIPA or West Coast IPA and split the batch into non-Thiolized and Thiolized versions. Use tetrad tests, descriptive analysis, and hedonic testing to determine whether there is a significant difference in the two samples and discover which one your tasters prefer. This is also a great opportunity to run some shelf life testing and see how the Thiolized version holds up over time.

To learn how this study was executed and how you can do consumer research, check out DraughtLab’s blog post. Our team would like to thank Lindsay Barr for her contributions to thiol sensory research and her endless curiosity!