top of page




Do biologically engineered yeast genetics bring differing presentations to a final beer? So...... a while back, with the assistance of Zack Weinberg of Toronto Brewing co. I brewed up some wort with the intention of testing Thiol conversion. Thiol converting yeasts side by side in the same basic hazy IPA type wort. I’m not interested in style points nor am I shooting for stellar beers here. I’m looking to test genetically altered yeast, how they vary, and the differences in how they would perform in a beer that the average person would brew. Not everyone is a pro right! What I'm looking to accomplish here isn't to perfect a beer but to see if the same wort, hopping schedules, and fermentation regimens will produce drastically different beers from two different genetically altered yeasts designed to emphasize Thiol conversion. The two yeasts being used are Omega yeast labs "Cosmic Punch" and Escarpment yeast Labs "Thiol Libre", both genetically enhanced yeasts designed to break down free thiols in wort. Thiols, as discussed in a previous post here (LINK) are bound organic sulfur compounds that once released and converted by the genetically augmented yeast create tropical aromas to the beer being fermented. With some hops and methods being better for the production of Thiols, you'll want to plan a bit before diving in with these yeasts. A Mash addition of hops is a good idea, along with the exclusion of most boil hops, beside a small bittering charge all other additions of hops will be post-boil in hop stands, and a few dry-hop additions to round things out. The recipe is as such:


Process and personal observations.

Brewing and Fermentation equipment are all Grainfather, a G30 connect for my kettle and Grainfather conicals with a Grainfather glycol chiller for fermentation. Closed transfers are made with a homemade transfer cap on the conical. Efficiency suffered due to grain bill size. So we'll start things off from my perspective. Since I wanted to make this a real-world experiment I disregarded any suggestions that the yeast labs had regarding grain choice since most new brewers, and even veterans won't follow the suggestion anyway. I tried to keep things within the realm of what's probable for most new brewers on the scene. Both beers had identical grain bills (to a few grams), hop profiles, and fermentation schedules. The only thing that differed was the yeast. Beers were close transferred into cO2 purged kegs with 1.5 oz of hops in a stainless mesh canister with an additional 3G of CaCl2 to the keg.

Thiol Libre

I've personally used Thiol Libre three times so I have a bit of experience with what I was to expect. Expectations are often different from what you've experienced previously, this time was no different. So a good amount of settled and packed yeast that required mixing before I opened the packet was the first thing I noticed, good and quick compaction of the yeast. Since both yeasts were mixed thoroughly before I stored them I didn't expect to find that much compaction in the short time the two yeasts were in the fridge, and even after mixing thoroughly with squishing of the corners it was still difficult to get every last straggler out of the pack of Thiol Libre into the starter (I succeeded though). The smell of the yeast was somewhat fruity with a mild citrus undertone with a noticeable tart yeasty aroma up front. During the brewing process, I kept my pH as consistent as I could and as close to 5.2 as I could manage throughout. I pitched the yeast into 17 degrees Celcius wort and fermented it there for 7 days, and ramped up to 20 C for 2 days to finish off allowing the yeast to clean up. During the fermentation process, the blowoff aroma was very citrus forward with a mild peach undertone giving it a slightly sharper nose than its experiment counterpart. The aroma from the blowoff post dryhop (Dryhop was added at high krausen, day 3) was noticeably more citrus with less of the stone fruit sharpness that was there previously. Fermentation was fast at the 17C temperature and was fairly capable of doing it's job taking a 1.069 beer down to 1.018 in less than a week. Once fermentation was complete the beer was cold crashed at 4C for 4 days and then transferred to the kegs for conditioning with an additional 3 grams of Calcium Chloride and the 1.5oz of keg hops. Since I didn't try these beers until the GTA Brews meet in early in January I can't express any tasting notes that were on the fresh side. This beer was likely past it's BB date and had sat on dry hops in keg way too long when the club tried it. But I didn't want to be biased by trying the beer before the public. Post-fermentation showed a few differences between the two yeasts that were somewhat unexpected. Since I had used Thiol Libre previously at two different fermentation temperatures I saw an artifact in the beers fermented a few degrees hotter than the other beer fermented at 3-4 degrees cooler. This artifact was a phenolic presence similar in nature to a Saison, which occurred in both beers when fermented at 17 and 18C which was not present in a beer that was fermented at a chilly 14C with Thiol Libre. These beers all contained Pilsner malts in the grain bill but a greater percentage was present in the warmer fermented beers. Could the spicy phenol be an artifact of the Pilsner and not fermentation temps, or an artifact of both factors? For consistencies sake, all three of these beers were fermented in the same Grainfather system with fresh packages of yeast for the starters.

Colour: Final colour on this beer was a few shades darker than the Cosmic Punch Sample. This artifact was present in the other two beers I fermented with Thiol Libre also. I'm not sure if this is an artifact of higher flocculation and protein drop or if it's a biological artifact causing the darker shades, but it is certainly something I've noticed after brewing three beers with it. These two beers being otherwise identical except for the use of Thiol Libre to ferment one of the two beers. Aroma: The aroma was far more citrus than tropical and more up front and pronounced than the Cosmic Punch, and since I used hops that should have provided lots of bio-transformable terpenoids there should in my mind have been much more of a tropical hop body to this beer. There wasn't, I was expecting much more mango, papaya and stone fruit, but it just wasn't there, unfortunately. And since I used hop amounts that would better reflect a person on a budget I wasn't expecting a hop bomb here, just a balanced mildly hopped hazy IPA with tropical notes. Instead, I got a mildly phenolic IPA with lots of citrus and some peach. Not a disappointment, just not something I expected in the tiniest way. Yes I could have used an alternate source of free thiols in the way of Phantasm, but this was an experiment based on simplicity and something anyone could brew.

Flavour: I found that the Thiol Libre beer presented much like a Saison or in some ways like a Kveik yeast. A Saison in that the beer presented drier, with less tropical fruit and a spicy phenol that could be desribed as Saison like. This translated to a slightly peppery note after the initial citrus and mild peach subsided. As Eric Cousineau pointed out, it would make a great yeast for a white IPA. Overall the flavour was pleasant with a certain charm of it's own, I certainly wouldn't balk at one if served to me.

Body: This Beer had a slightly better body although it fermented 3 points lower than the Cosmic Punch beer. It also wasn't as soft and creamy in the mouthfeel as the Cosmic punch fermented beer, which I found odd considering they both had identical Chloride additions. Overall it was a good beer with an odd phenol lurking on the back end which wasn't offputting but certainly made it's presence known.

Cosmic Punch

I've personally used Omega yeasts twice, so I had no idea what to expect with their Thiol converting yeast. Once again, everything was exactly as the Thiol Libre beer so the process didn't change from beer to beer. This beer also started at an OG of 1.069 but it finished at 1.022 for a final ABV of around 6.2%, compared to the Thiol Libre at 6.4%. The higher FG is due partially to my high mash temps, and less an artifact of inefficient yeast. So don't judge the yeast efficiency from my data, I intended for the beers to be a higher FG.

Colour: Final colour on this beer was a few shades lighter than the Thiol Libre Sample. This beer also seemed to hold on to haze slightly better also, which may have contributed to the presentation of it being lighter in colour. I'm not sure if this is an artifact of lower flocculation, but it is certainly something I noticed when the two finished beers were put side by side. During the A/B test the amount of stable haze was pretty similar but showed the Cosmic Punch was lighter in colour. Aroma: The aroma of Cosmic Punch was far more tropical. It was a mix of Pineapple, Papaya and Peach for me, with a slight pear in the background, but certainly softer and less up front than the Thiol Libre sample. I found it much more subdued than the Thiol Libre in aroma but presented more of the desired tropical notes I was looking for.

Flavour: I found that the Cosmic Punch sample was far and away the better beer of the two in this department. It was somewhat juicy, with loads of stone fruit, citrus, and rounded bitterness due to the Calcium chloride levels, and not much in the way of off flavours I could detect. This beer was on the opposite end of the spectrum compared to the Thiol Libre sample, the beers were nothing alike at all, all things considered, when it comes to all the other processes, they couldn't have been more unique from one another. I personally preferred the Cosmic punch sample myself as it was more along the lines of what I was shooting for in the final product.

Body: This Beer had a slightly thinner body, even though the creaminess of the Cosmic Punch beer gave a false sense of thickened body, after swallowing the beer you could notice a slightly thinner mouthfeel on the backend. The carbonation was good, and overall it was a decently balanced beer.

Public observations:

I was able to coral 20 participants excluding myself and two neighbors who just gave me their preferred beer without too much input. Out of these 23 participants, Approx 61% or 14 participants chose beer "A" as their preferred beer, which was the Cosmic Punch beer. The final 9, or 39% of participants preferred beer "B" which was the Thiol Libre sample. Most found the Cosmic Punch to be much easier drinking, but the Thiol Libre beer was a bit more exciting and balanced.

Colour: Most of the participants didn't notice the colour differences, only about half made comments on the lighter colour of the Cosmic Punch beer. Although not drastically noticeable post conditioning there was still those who noticed the darker shade to the Thiol Libre beer.

Aroma: The winner of the aroma award for most of the participants was directed towards the Thiol Libre camp, it was simply much more vibrant with a nose that was much more pronounced than the Cosmic punch camp. Most found the Thiol Libre much more Citrus, grapefruit with mild yellow stone fruits, and the Cosmic punch a more tropical aroma with citrus, mango, papaya, and pineapple being the primary scents pulled out of the CP.

Flavour: Well here's where it gets interesting, although 14 participants found the Cosmic Punch to be their preferred beer, there were several comments stating that the Thiol Libre beer was more exciting and less one-dimensional. Could this be an artifact of the white pepper phenol presence, or simply that the body of the Thiol beer was certainly different than that of the Cosmic Punch beer? Also, a common comment from the participants was that the Cosmic Punch was just much hoppier than the Thiol Libre in the flavour department, considering both beers had the exact same hop additions it seems counterintuitive, but it is what it is. The general consensus is Cosmic Punch for overall flavour, Thiol Libre for multi-dimensionality.

Body: Most agreed that the body of the Cosmic Punch was much creamier, and less heavy with a different residual sweetness. Carbonation was similar on both beers but the Thiol beer seemed more carbonated due to its sense of body not being as creamy as the Cosmic Punch, which had the Thiol Libre beer present somewhat like a Kveik in its finish. Most felt the body on the Thiol samples were fuller, but the Cosmic punch presented as much easier drinking all around.

Conclusion? All in all I believe this turned out well, we learned that genetics are funky, and no matter how you cut the apple, there will always be differences in the slices. We learned that although the new brewer could certainly brew a great beer with these yeasts, it's likely better suited to those who have some experience and aren't afraid to experiment with things like grape pumice and Phantasm to increase thiols available for conversion. Certainly, an exbeeriment worth doing. Till the next one, Take care and brew hard! The Bearded Buddha

Ingredients provided by and or outside sources were applicable.

bottom of page