Author: Marshall Schott

Said to be used by Sierra Nevada Brewing Co. and known for it’s clean fermentation character that allows malt and hops to shine, the “Chico” strain of yeast is likely the most commonly used by professional and homebrewers around the world. I’m not sure if it’s due to its popularity or if it is the reason for its popularity, but nearly every commercial yeast lab offers their version of this strain including White Labs WLP001 California Ale and Wyeast 1056 American Ale, both in liquid form, as well as Fermentis’ Safale US-05 American Ale, which is a dry variant.

Denny Conn and Drew Beechum from the Experimental Brewing podcast recently had their group of IGORs compare WLP001 to Wyeast 1056 with results suggesting each strain imparted a unique enough character that tasters could tell them apart. I was admittedly surprised by their results, enough so that I added the same comparison to our increasingly long list of variables. However, these results made me even more curious about the dry version of the so-called Chico strain, Safale US-05, which is an oft recommended substitute for the liquid varieties. Given their clean fermentation profiles, I’d always presumed these yeasts, even if slightly different on a genetic level, likely wouldn’t produce large enough differences in character for tasters to tell the difference. Curious if this presumption of mine was wrong, I figured the best thing to do was test it out for myself!

| PURPOSE |

To evaluate the differences between two beers fermented with yeasts believed by many to be the same strain, WLP001 California Ale yeast or Safale US-05 American Ale yeast.

| METHODS |

Given the fact both of these yeasts are sort of known for being great Pale Ale fermenters, I opted to split a recent batch of beer for The Hop Chronicles and ferment either with a different yeast.

Similarly Different Pale Ale

Recipe Details Batch Size Boil Time IBU SRM Est. OG Est. FG ABV 5.5 gal 60 min 33.5 IBUs 5.1 SRM 1.054 1.013 5.4 % Actuals 1.054 1.012 5.5 % Fermentables Name Amount % Pale Malt (2 Row), Rahr 10 lbs 85.56 Vienna Malt 1.187 lbs 10.16 Victory Malt 8 oz 4.28 Hops Name Amount Time Use Form Alpha % Loral 14 g 60 min First Wort Pellet 9.2 Loral 14 g 20 min Boil Pellet 9.2 Loral 30 g 5 min Boil Pellet 9.2 Loral 30 g 3 days Dry Hop Pellet 9.2 Yeast Name Lab Attenuation Temperature California/American Ale (WLP001 or US-05) White Labs/Fermentis 77% 68°F - 73°F Notes Water profile: Yellow Bitter in Bru’n Water

Two days prior to brewing, I made a large starter of WLP001 California Ale yeast, using my preferred yeast calculator to determine the extra amount needed to harvest some for later use.

While collecting the full volume of water for this 10 gallon no sparge batch, I weighed out and milled the grains.

I woke up early the following morning and immediately began heating the liquor.

When the water was a few degrees warmer than the strike temperature suggested by BeerSmith, I transferred it all to my mash tun, let it sit for a few minutes to pre-heat, then stirred the grains in to hit my target mash temperature.

I took a pH reading 15 minutes into the mash that showed I was within the acceptable range, though it was a bit higher than desired due to a recent change in my municipal water source.

The mash was left alone an hour with brief stirs every 20 minutes to encourage complete conversion.

At the end of the mash step, I collected the wort, transferred it to my kettle, and began heating it up. While waiting to reach a boil, I measured out the kettle hop additions.

The wort was boiled for an hour with hops added as laid out in the recipe.

At the conclusion of the boil, I quickly chilled the wort to my target fermentation temperature of 66˚F/19˚C.

A refractometer measurement at this point confirmed I’d hit my target of 1.054 OG.

I proceeded to rack 5.5 gallons/21 liters of chilled wort to 2 separate stainless fermentors, stirring gently throughout to ensure equal distribution of kettle trub.

With the fermentors moved to my temperature controlled chamber, I rehydrated a pack of US-05 yeast in 90˚F/32˚C water for 15 minutes, during which I harvested some WLP001 from the starter.

Once proper rehydrated, I pitched the yeast and left the beers alone for 6 hours before returning to discover the WLP001 batch had developed a small kräusen while the US-05 beers appeared unchanged. The following evening, both beers were actively fermenting. After 4 days of active fermentation, I raised the temperature in the chamber to 71˚F/22˚C to promote complete attenuation. After 2 more days, activity had slowed drastically in both batches so I took hydrometer measurements that suggested each had reached FG. I added the same dry hop charge to both beers at this point then took more hydrometer measurements 2 days later that matched the first.

The beers were cold crashed overnight, fined with gelatin, then eventually racked to kegs.

The kegs were placed in my cold keezer where they were burst carbonated for 18 hours before I reduced the CO2 to serving pressure and allowed the beers to condition for another few days before serving them to participants. While both were quite clear, the batch fermented with US-05 appeared noticeably brighter than the WLP001 beer.

| RESULTS |

A panel of 23 people with varying levels of experience participated in this xBmt. Each taster, blind to the variable being investigated, was served 1 sample of the beer fermented with WLP001 California Ale yeast and 2 samples of the beer fermented with Safale US-05 American Ale yeast in different colored opaque cups then instructed to select the unique sample. While a total of 12 correct selections would have been required to achieve statistical significance, 15 tasters accurately identified the unique sample (p<0.05; p=0.002), suggesting participants in this xBmt were able to reliably distinguish a Pale Ale fermented with WLP001 from one fermented with Safale US-05.

The 15 participants who made the correct selection in the triangle test were instructed to compare only the 2 different beers, still blind to the variable in question, and asked about their preference. In all, 6 tasters reported preferring the beer fermented with WLP001, 5 said they liked the US-05 fermented beer more, 1 person had no preference despite noticing a difference, and 3 tasters felt there was no difference between the beers.

My Impressions: I fully expected these beers to taste the same, as I’d accepted they came from the same original source or were clean enough fermenters that any differences would go largely unnoticed. Bias be damned, I was wrong! From the very first time I compared the beers once kegged and carbonated, I perceived what I thought was a rather drastic difference that left me very curious how I’d perform on blind triangle tests. I attempted 8 trials over a 2 week period and was able to identify the odd-beer-out… every single time. The beer fermented with WLP001 was very clean, allowing the malt and hops to take a starring role; while I’d still describe the US-05 fermented beer as clean, it had an interesting spiciness to it, not necessarily phenolic, and it was quite subtle. My preference when choosing blindly was consistently for the WLP001 fermented beer.

| DISCUSSION |

There are times I wonder if I’ve become somewhat desensitized to certain xBmt results, for example I rarely find it surprising when a yeast comparison yields statistically significant results– different yeasts make different beer, whoopee. Not the case with this one. What gets me about this xBmt is that the yeast strains compared, WLP001 California Ale and Safale US-05 American Ale, are touted by so many as being the same, for all intents and purposes. With every xBmt article published, a handful of people make comments questioning our methodology and subsequent validity of the results, a sentiment I shared in regards to the Experimental Brewing results suggesting WLP001 produced a noticeably different beer than Wyeast 1056, it just seemed so incredibly unfeasible to me.

And yet, here I sit, typing up results that add more evidence to the notion that these yeasts are indeed different, despite the commonly accepted belief they’re not. After analyzing these results, I recalled a fascinating forum thread I happened upon a couple years ago where an appropriately named user mentioned all the popular Chico strains originated from the same source, a yeast the Siebel Institute refers to as BRY-96. While commercial labs producing a version of this strain may have sourced their original yeast from BRY-96, they’d all be forced to isolate specific cells for further propagation and selling. It seems plausible to me that the differences noted between these yeasts could be function of genetic drift due to natural mutation over time. If this be the case, I can’t help but wonder how things might look later on down the line.

If you have experience fermenting with Safale US-05 and/or WLP001 or you have thoughts about this xBmt, please share them in the comments section below!

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