exBEERiment | Yeast Comparison: White Labs WLP001 California Ale vs. Safale US-05 American Ale In A Session IPA

Author: Martin Keen

Wort becomes beer at the point it is introduced to yeast, at which point fermentation occurs, turning the present sugars into alcohol and CO2. There are many yeasts available to brewers these days that contribute their own unique characteristics to beer, though there are also various versions of strains that are said to come from the same source, leading many to view them as interchangeable.

Said to be the most popular ale yeast, what is colloquially referred to as the “Chico” strain was originally sourced from Sierra Nevada Brewing Company, who apparently got it from Ballantine Brewing. Nearly every modern lab offers a version of the Chico strain, two of the most popular being White Labs WLP 001 California Ale and Safale US-05 American Ale. Despite sharing the same source, some brewers contend these strains produce perceptible differences in beer, meaning they aren’t as interchangeable as many believe.

Results from one prior xBmt comparing WLP001 to US-05 in an American Pale Ale were significant, though in a similar follow-up xBmt performed by a member of The Brü Club, tasters couldn’t consistently tell apart beers fermented with either US-05 or Wyeast 1056 American Ale yeast, yet another version of Chico. Having recently picked up the dry version of WLP001, I decided to repeat this comparison in a Session IPA and collect data at Homebrew Con 2026.

| PURPOSE |

To evaluate the differences between a Session IPA fermented with White Labs WLP001 California Ale dry yeast and the same beer fermented with Safale US-05 American Ale yeast.

| METHODS |

For this comparison, I went with a simple Session IPA recipe, as it aligns with common usage and I thought it’d allow any differences to be noticeable.

Session For Session

After collecting the full volume of filtered tap water for a 6 gallon/23 liter batch, adjusting it to my desired profile, and heating up, I incorporated the crushed grain into the mash and set my controller to maintain 152°F/67°C.

During the mash rest, I weighed out the kettle hop additions.

Once the mash was finished, I removed the grains, boiled the wort for 60 minutes, then after a 20 minute hop stand at 170°F/77°C, I quickly chilled it before taking a refractometer reading.

At this point, I pitched a single sachet of WLP001 into one wort while the other was hit with the same amount of US-05.

With signs of activity absent after 2 weeks of fermenting at 68°F/20°C, I took refractometer reading showing a minimal difference in FG.

At this point, I cold crashed the beer overnight then pressure-transferred each to CO2 purged serving kegs that were placed in my keezer. After 3 weeks of conditioning, I transported the carbonated beers with me to Homebrew Con 2026 in Asheville, NC and served them to blind tasters. Unfortunately, the finished beers were gone before I had a chance to get photos of them.

| RESULTS |

A total of 84 people of varying levels of experience participated in this xBmt. Each participant was served 1 sample of beer made with White Labs WLP001 California Ale yeast and 2 samples of the beer made with Safale US-05 American Ale yeast in different colored opaque cups then asked to identify the unique sample. While 36 tasters (p<0.05) would have had to accurately identify the unique sample in order to reach statistical significance, 52 did (p=0.00000001), indicating participants in this xBmt were able to reliably distinguish a Session IPA fermented with White Labs WLP001 California Ale yeast from one fermented with Safale US-05 American Ale yeast.

The 52 participants who made the accurate selection on the triangle test were instructed to complete a brief preference survey comparing only the beers that were different. A total of 12 tasters reported preferring the beer made with WLP001 California Ale yeast, 31 said they liked the beer made with US-05 American Ale yeast, 7 had no preference despite tasting a difference, and 2 reported perceiving no difference between the beers.

My Impressions: The kegs kicked before I had the opportunity to complete a set of semi-blind triangle tests, but anecdotally, while I did think the beers were slightly different from one another, they were definitely similar – crisp, hoppy, and refreshing.

| DISCUSSION |

Of the several ingredient choices a brewer makes when constructing a beer recipe, yeast is viewed as being one of the more important, though many view similar strains from different labs as being one-in-the-same. Interestingly, tasters in this xBmt were able to reliably distinguish a Session IPA fermented with White Labs WLP001 California Ale yeast from one fermented with Safale US-05 American Ale yeast.

Seemingly, the most plausible explanation for this result is that, while these different labs may have sourced their yeast from the same place, each one relied on specific isolates that were different. Over years of re-propagation, those cells took their own evolutionary paths that, while generally like one another, produce their own unique characteristics as well.

I’ve heard the arguments about versions of Chico from different labs being different, though I admittedly chalked it up to people being overly critical or nitpicky. While these beers were certainly very similar, the blind taster results indicate they were perceptibly different, and the most probable reason for that is the yeast. That said, I was pleased with these beers and wouldn’t hesitate to use either WLP001 or US-05 in the future, though I am curious to see how dry WLP001 compares to its liquid counterpart.

If you have any thoughts about this xBmt, please do not hesitate to share in the comments section below!

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