Author: Marshall Schott

I began harvesting yeast from starters over 2 years ago after trying my hand at rinsing yeast… and hating it. Since then, I’ve taken yeast out as far as 15 generations without any noticeably negative impact on the finished beer, at least to me and my pals. I’ve heard a number of professional brewers talk about how they actually get the best performance out of their yeast, it “hit its stride,” at around the 4th through 6th generations. To be sure, nearly every beer I’ve done well with in competition has been fermented with harvested yeast. I’ve also been asked numerous times since posting about my yeast harvesting method if I’ve ever compared harvested yeast to a fresh vial. I hadn’t, until now.

| PURPOSE |

To evaluate the differences between two beers made from the same wort and pitched with the same yeast strain, one from a fresh vial and the other a 4th generation harvested multiple times from prior starters.

| METHODS |

Given the potentially subtle differences, I thought it would be best to make a lighter beer and settled on splitting a 10 gallon batch of my 1.047 OG Munich Helles. Unfortunately, I was forced to use German Pils malt in place of the Belgian Pils listed in my recipe due to lack of availability. With a brew day of June 7, 2014 planned, starters were made for both yeasts about 2 days ahead of time. Yeast Calculator was used to determine starter sizes for both yeasts, including an additional liter for subsequent harvesting. A 100bil initial cell count was assumed for the harvested starter and the prior date of harvest was used for production date.

A quick caveat before we go any further: The harvested starter was calculated to have slightly more than double the amount of cells as the vial starter due to the fact I was splitting that starter to use half in a batch of Märzen… hey, I have a big party coming up that I need beer for. I took great care to make sure the starter was well homogenized prior to being evenly split. This is something I’ve successfully done many times in the past.

Both starters were showing signs of activity within 8 hours.

The kräusen in the harvested flask was significantly larger at this point, though the other one caught up soon after.

The morning of brew day, I harvested a liter off of each starter (for future use) and split-off the portion of the harvested starter that would be used for the other beer.

Both starters were then placed in the cool fermentation chamber where they would be left overnight to crash while the wort was chilling to my target pitch temp. Brewing commenced later that afternoon, all went as expected.

Once the wort was chilled to just above groundwater temp, which was a balmy 74°F, I immediately filled both carboys, trying to get about the same amount of kettle trub into each one, something I thought might be important given the results of the last exBEERiment.

The carboys were placed in the fermentation chamber and allowed to chill down to my preferred pitching temperature of 56°F.

I decanted the starters early the following morning, approximately 12 hours after the wort was placed in the chamber.

A simple observation revealed the yeast cakes at the bottom of each flask to be almost exactly the same in terms of thickness and color. The yeasts were pitched!

I noticed the first signs of activity after about 13 hours, which is about what I expect when I ferment WLP029 so cool.

I was surprised to discover the beer pitched with the fresh vial becoming active prior to the beer with the harvested yeast, particularly given how different the starters were. Even after an additional 11 hours, 24 since pitch, the harvested yeast was lagging behind the vial.

I found it somewhat odd that the Märzen pitched with the harvested yeast and having a very similar OG was fermenting more like the Helles pitched with the vial.

It took 36 hours before the beer with the harvested yeast caught up with the others, at which point my anxiety dwindled and things seemed to proceed more as I expected.

Both beers were still active 60 hours since pitch with the vial beer obviously further along than the harvested.

On the morning of the 4th day since pitch, I began ramping the temp in my chamber from 58°F to 65°F to encourage complete attenuation. I usually do this 3 days after pitching but thought it most prudent to do it a day later due to the extended lag of the harvested yeast. Activity in both beers had decreased significantly by day 6.

I measured the specific gravity for the first time a week after pitching the yeast.

Interesting finding #1: The beer fermented with the fresh vial seemed to finish .002 points lower than the beer fermented with harvested yeast. Any differences in color, flavor, and aroma were imperceptible to me at this point. I took a final SG measurement 2 days later, 9 days after pitching the yeasts, and found the vial beer to be 1.010 while the harvested beer had dropped to 1.011, which was consistent with measurements a few days later, at which point the beers were kegged and put on gas to carbonate.

The tasting commenced during a 4th of July party I held at my house in which many homebrewers attended. The beers had been on gas in my 38°F keezer for exactly 2 weeks at this point. Data was collected using an online survey tool (click here to see the survey), which tasters received via text message just prior to evaluating the beers. Each beer was randomly given a name of a character from one of my favorite movies: Lloyd (fresh vial) and Harry (harvested). Tasters were instructed to take their time evaluating the beers in relative privacy just after arriving to my house, before drinking too much. With one exception, the tasters were unaware of the nature of the exBEERiment and blind to which beers were represented by the character names. Once each taster completed the survey, they were asked not to discuss their experience with others who had yet to do the evaluation.

| RESULTS |

The beers were evaluated by 9 tasters ranging from homebrew club board members with years of brewing experience to a couple guys who typically drink Coors Light. Before getting into each taster’s subjective impressions, I’ll share some of the hard data:

– 67% believed Lloyd had the better appearance, no one claimed there was no difference

– 67% believed Harry had better aroma, 1 taster (11%) believed there was no difference

– 67% believed Lloyd had better flavor, no one claimed there was no difference

– 56% believe Lloyd had better mouthfeel, 2 tasters (22%) believed there was no difference

– 78 % said they preferred Lloyd, 1 person (11%) preferred Harry and 1 had no preference

– 44% accurately guessed which beer was fermented with the harvested yeast

Matt Humann is the Vice President of our local homebrew club and has been brewing for many years. He noticed both beers to have a “slight haze,” though did not comment on any other significant differences in appearance. In terms of aroma, Matt said that Lloyd “almost has a Beligian aroma” while Harry is “more pleasant.” He experienced Lloyd as being “very thin in comparison” to Harry, which he also thought had better flavor. His overall preference was for Harry, which he accurately predicted was fermented with the harvested yeast.

Sean Wood, president of the homebrew club, preferred Lloyd to Harry in all areas, describing Harry as having a “slightly too sweet and grainy” aroma with a flavors was “a little flabby and bland.” He perceived Lloyd as being slightly clearer and drier with a flavor that “seemed to pop a little more.” His obvious preference was for Lloyed, which he wrongly guessed was fermented with the harvested yeast. He also thought it important to comment, “Marshall likes dudes’ balls in his mouth,” which I am hesitant to corroborate at this time.

Heather Wood is a Cicerone Certified Beer Server at the House of Pendragon tasting room, as well as loving (and incredibly patient) wife of Sean. She thought Lloyd was better than Harry in all areas except mouthfeel, in which she believed there to be no perceptible difference. She commented that Harry “smelled a little skunky in comparison” to Lloyd. Her overall preference was for Lloyd and she was one of the 4 tasters to accurately identify Harry as being fermented with the harvested yeast.

Corey M. is a cool dude who recently switched from extract to all grain brewing using the BIAB method. He thought Lloyd bested Harry in all areas except aroma, where he commented it smelled “a bit sweeter” while Lloyd was “beerier.” He threw his overall preference at Lloyd, which he incorrectly guessed was fermented with the harvested yeast.

Chris Padalinski has been homebrewing for 3+ years and enjoys taking beautiful photos of beer. He is the one taster who was aware of the nature of this exBEERiment, though he was blind to which beer was in the glasses served to him. He described the appearance as being “identical except for the tiniest difference in clarity,” with Harry winning out. He experienced Lloyd as having “slightly more potent aroma” with a mouthfeel that was “a bit smoother” than Harry. While he to pointed out how similar both beers were in general, he said his “clear favorite” was Lloyd, which he inaccurately believed to be fermented with the harvested yeast.

John Toepfer has been homebrewing for a few years and makes the best damn salsa verde on Earth. He perceived Lloyd as being “more clear” and having “brighter” flavor” than Harry, while he experienced Harry as having “ever so slightly bolder” aroma with better mouthfeel, which he guessed could indicate a higher finishing gravity. His favorite was Lloyd, which he inaccurately though was fermented with harvested yeast.

Tim M. is my neighbor, a really good dude who is always willing share his ice cold Coors Light with me, which I always readily accept. Over the last year or so, he has come to appreciate some of the finer sides of beer. Or he just likes free beer. Either way, I thought it’d be cool to include someone less familiar with craft beer in this exBEERiment. While he thought Harry had better appearance, aroma, and flavor, he selected Lloyd as the one he preferred overall… perhaps the mouthfeel is what got him, I don’t know. He also incorrectly chose Lloyd as the beer fermented with harvested yeast.

Wes Tarvin is a fantastic homebrewer who has been enjoying the hobby for years. He’s also a man of few words, leaving no detailed comments. He perceived Lloyd as having better appearance and flavor, while he thought Harry had better aroma; he was unable to tell the difference between the beers in terms of mouthfeel. He correctly guessed Harry as being the beer fermented with harvested yeast and reported having no real preference for either one, explaining later he thought they were both very good. I should say here that he was fermenting a batch of this very same Munich Helles at the time of the tasting, I believe he used a fresh vial of yeast for his.

Joe Schmidt, my brother-in-law, started brewing beer right around a year ago using a small batch BIAB setup in his Berkeley apartment. He thought Lloyd beat Harry in terms of appearance and mouthfeel, while he experienced Harry as having better aroma and flavor. His overall preference went to Lloyd, which he later explained was very slight, and he accurately chose Harry as the beer fermented with harvested yeast.

My Impressions: I actually started drinking these beers a couple days before the July 4th party and, biased as it most certainly is, came to some personal conclusions that I maintain after multiple tastings. First off, both beers taste good, the differences are slight enough that most folks likely wouldn’t be able to tell them apart if served at different times. I personally experience a very slight vegetal-like aroma and flavor in Lloyd, which I wouldn’t have expected given it was fermented with a fresh vial of clean yeast, it seemed to take-off faster, and fermented healthily. Over the weekend, I had many samples of both beers poured into numerous types and sizes of glass, I’m convinced they are the same in terms of color and clarity. Like some of the other tasters commented, Harry does seem to have an ever-so-slightly fuller mouthfeel, which I’m compelled to contribute to the fact it finished .001 SG point higher than Lloyd… but really? I am solidly in the camp that prefers Harry over Lloyd, though I will happily polish off both kegs without complaint.

| DISCUSSION |

According to the data collected in this exBEERiment, there would appear to be a general preference for the beer fermented with a fresh vial as opposed to harvested yeast. Not only did this surprise me a bit, as I was certain this 4th generation yeast would far outperform it’s less experienced competitor, but it was initially a bit of a downer given the fact many of us religiously harvest yeast from starters with the expectation of at least similar quality. As I pondered these results, going over in my mind whether I should stop encouraging folks to harvest from starters, I had to remind myself of a few things:

1. This is only 1 test that should (and will) be repeated numerous times in the future.

2. The “harvested” beer was still delicious and even preferred by some (myself included).

3. There are other potential factors at play.

Moreover, when asked later, every taster who reported a preference for Lloyd said the differences weren’t strong enough to stop them from harvesting yeast from starters in their own brewing.

In the end, I’m not sure anything terribly conclusive can be gleaned from this exBEERiment, which again seems to validate the subjective nature of perception and preference when it comes to beer. While the beer fermented with a fresh vial won the preferential pick from more folks, I would contend the comments of the tasters both during and after the evaluation validate the idea that delicious beer can be produced using harvested yeast.

As a quick aside, the Märzen I made using half of the harvested WLP029 starter was by and far the favorite beer of the night judging by the fact it was the only keg (which was full) that kicked before the night was over.

A huge thanks to all the cool folks who participated in this by being on the tasting panel, assisting me with the survey stuff, and sharing with me what I think was a really cool idea for an exBEERiment.

Please do share any thoughts or opinions you might have about this, I’m sure there are plenty! If you’ve done something similar, perhaps using rinsed yeast from a cake, I’d love to hear about it. Cheers!

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| Read More |

18 Ideas to Help Simplify Your Brew Day

7 Considerations for Making Better Homebrew

List of completed exBEERiments

How-to: Harvest yeast from starters

How-to: Make a lager in less than a month

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