Author: Ray Found

We’ve all heard it. Hell, we’ve probably all said it: “A single vial or smack pack, regardless of what it says on the package, isn’t enough yeast to perform a healthy and proper fermentation on 5 gallons of most styles of beer.” I know I have. As beer drinkers go, I am pretty tolerant, but the one thing I cannot stand is an under-attenuated, sticky-sweet mess. Call it what you want, but as a new brewer I learned the key to avoiding a cloying disaster was to mash low and, perhaps more importantly, pitch a ton of yeast.

On the other side of the coin, yeast suppliers, White Labs in the case of this xBmt, provide instructions on their packaging that differs substantially from this commonly accepted homebrewer wisdom, suggesting a single vial is sufficient for 5 gallons of wort up to 1.070 OG.

I have been working on developing an easy drinking West Coast Amber Ale, the type of beer I buy when I’m out of town and don’t know what’s good, something that may not blow your socks off, but always pleases. My perfect Amber (which I have yet to find commercially) would be firmly bitter, aromatically hoppy, with a complex and sweet balancing malt profile. It would never, ever, be under-attenuated. Despite a fairly robust 6%+ ABV and medium body, my dream beer would be supremely drinkable with every pint leaving me wanting another. What better beer, then, to test just how important pitch rate is to achieving that fully-attenuated, crisp finish I long for?

| PURPOSE |

To evaluate the differences between a split-batch of the same wort, half pitched with a single “pitchable” vial of yeast and the other half pitched with an adequately sized yeast starter.

| METHOD |

After much soul searching (ahem… drinking), grain chewing, and brewing this over and over in my mind, I finally settled on a recipe consisting of zero American Crystal malts.

American/West Coast Amber Ale

Batch Size Boil Time IBU SRM OG FG ABV 11 gal 60 min 62 15.6 1.063 SG 1.015 SG 6.3 %

Fermentables

Name Amount % Domestic 2-Row 15 lbs 4 oz 67.5 Munich (10L) 5 lbs 7 oz 20.0 Gambrinus Honey Malt 2 lbs 3 oz 8.0 Special B 13 oz 3 Pale Chocolate 6.5 oz 1.5

Hops

Name Amt/IBU Time Use Form Alpha % Magnum 20 IBU First Wort Hop FWH Pellet 12.0 Columbus 28 g/6.6 IBU 15 min Boil Pellet 17.0 Centennial 155 g/22 IBU Flameout w/ 15 min stand Boil Pellet 10.2 Mosaic 84 g/13.7 IBU Flameout w/ 15 min stand Boil Pellet 15.0

Yeast

Name Lab Attenuation Ferm Temp San Diego Super Yeast White Labs 090 75% 66°F

The yeast starter calculator projected I would require 237 billion cells given my expected OG, yeast manufacture date, and 5 gallon batch size. Extrapolating from the information provided on the packaging and based on what we’ve been taught about yeast viability, we can assume the vial being pitched on its own contained approximately 56 billion cells, while the starter would be propagated to approximately 400% that amount, and pitched into the starter batch. I made a starter a couple days prior to brewing, making sure to overbuild to harvest some for future use.

After a couple days, the starter was crashed overnight, decanted, then the remaining slurry was allowed to return to ambient temperature in preparation for pitching. The single vial was removed from the fridge the morning of brew day and allowed to warm up for a few hours prior to being pitched.

I performed a single infusion mash in my new Coleman Xtreme 70-Quart MLT and nailed my target mash temp.

An hour later, the sweet wort was collected and subsequently transferred to my boil kettle where it met a charge of Magnum hops.

The wort was boiled for 60 minutes with hops being added at 15 minutes and flameout.

Following the 15 minute hopstand, my JaDeD Brewing Hydra IC (thanks Mom! One of my favorite Christmas gifts) was put to use, dropping the temp of my wort to 72°F in under 10 minutes.

A hydrometer sample revealed a SG of 1.065, which thanks to my poorly calibrated hydrometer consistently reading .002 points too high, meant I hit my expected 1.063 OG.

The wort was equally split into separate 6 gallon PET carboys, moving the hose back and forth to ensure both received similar amounts of kettle trub. I shook to aerate (my normal method) then placed both carboys in my temp controlled fermentation chamber.

I went ahead and pitched at 72°F, and set my fermentation chamber to my target ferm temp of 66, one batch was dosed with a single vial of WLP090 while the starter slurry was pitched into the other carboy.

As is usually the case, within 7 hours of pitching yeast, the starter-pitched beer had already formed a substantial krausen and was showing all the normal signs of active fermentation I’d come to expect. The vial-pitched beer? Yeah…not so much.

At 18 hours in, the vial-pitched beer appeared unchanged while the krausen continued to build on the starter-pitched beer.

The krausen reached the top of the carboy starter-pitched carboy just a couple hours later, it was going bonkers. Still nothing in the vial-pitched batch.

By 26 Hours, the blowoff tube was proving necessary on the starter-pitched beer. The absence of any signs of fermentation in the vial-pitched beer was beginning to make me nervous, I’ll admit. It looked dead.

With only minimal sings of life at 31 hours in, I began wondering if I was going to lose 5 gallons of beer.

Finally, at 42 hours post-pitch, a full 36 hours after the the starter-pitched beer came alive, the vial-pitched beer had developed a krausen.

Throughout the remainder of fermentation, the starter-pitched beer maintained a more vigorous fermentation as evidenced by a larger krausen, greater blowoff, and finishing quicker.

I don’t usually disturb my beers before they’re done fermenting, but curiosity got the better of me and I pulled a gravity sample 4 days after pitching. The starter-pitched beer had nearly reached FG while the vial-pitched beer still had a ways to go.

At this point, I let the beers ride for a few more days at 66°F before ramping the temp to 72°F. A couple days later, 9 since pitching the yeast, I checked the SG again and discovered something surprising to me- both beers had finished at an identical 1.015 SG.

The beers were cold crashed, fined with gelatin, and after a few days, racked to kegs and carbonated. Data collection commenced about a week later.

| RESULTS |

A huge thanks to the Vince, Cameron, and Ray from Brew Crew, a nano-brewery incubator that recently opened in Riverside, CA, as well as the cool folks at Brew Toys, a new Riverside homebrew shop, for participating.

Thanks also to Ken Smith and the 13 other rad members of the Gambrinus Malting crew for taking time out of your day to contribute your palates to dorky homebrew science!

With a total of 20 participants, 11 correct responses would be required to reach statistical significance (p<0.05). Only 9 panelists correctly identified the different beer, suggesting a moderate OG beer fermented with a single vial of yeast is not reliably distinguishable from the same beer fermented with an adequately sized starter. Comments by the accurate tasters about the nature of the differences were not aligned in any noticeable trend, no one was able to correctly guess what the variable being tested was. I found it interesting that of the 9 participants who made it past the triangle test survey and to the blind comparative evaluation, 8 selected the starter-pitched beer as the one they preferred. Of course, due to our failure to reach statistical significance on the triangle test, this data ought to be interpreted with caution and, at the very least, taken with a massive dose of salt.

The results provided a pretty clear illustration of why using statistical significance is important: 8 participants chose green as being different. Just 1 shy of the red count, despite the fact that green was identical to blue.

My Impressions: I was able to identify the different beer in the two triangle tests I took, though it’s likely this was largely influenced by my obvious bias, as I found the differences to be extremely slight. Who knows how I would have performed if I had been unaware of what this xBmt was about? Personally, I perceived the starter-pitched beer has having slightly more hop aroma with a slightly less sharp flavor, however, when I tried the two side by side recently, I chose the wrong one as being the starter-pitched beer. Frankly, for a beer I was very nervous about, given the early fermentation being so sluggish, I was pleased at how subtle the differences between the beers ended up being and enjoyed drinking both batches.

As for the recipe, it’s an okay Amber, a rough draft that needs a few iterations to develop into something great. I’d be fine drinking this beer in a pub or restaurant with dinner, it is perfectly pleasant, but it can be made better.

| DISCUSSION |

I’m inclined to defer to the yeast labs here and suggest that perhaps they know a thing or two about how their product is going to perform. At the same time, the fact a beer made with a single vial of yeast pitched directly into wort was not reliably distinguishable from a beer fermented with a “proper” amount of cells propagated in a starter, well, that sort of bewilders me. Chris White has hinted that a lot of the pitch-rate calculations are based on commercial breweries, where they are re-pitching from one fermentor to another, and that lab-grown yeast will perform differently, perhaps that has something do with it. But still, the sluggish start and overall slower completion time of the vial-pitched beer was not ideal, in my understanding at least. In that 36 hour lag time, any beer spoiling microorganisms that made it beyond my sanitation attempts could have been multiplying and ruining my beer. Additionally, the slower completion time means a slower overall turnaround for a batch, if only by a couple days – this makes a difference if I am trying to get a beer ready for an event of some kind.

I’m interested to see this xBmt repeated at some point with a beer that is yeast-driven in nature, like an English or Belgian style ale, as my inclination is that we may potentially see different results when yeast character is the star of the show. That being said, as homebrewers, we sure make a lot of American-style Pale, Amber, and IPA, and my hunch is these results would likely transfer to any of those styles, as we likely all know (or have heard from) plenty of brewers who make tasty beer using a single vial of yeast.

Do I have plans to change my process as a result of these findings? Absolutely not! I will continue making starters from liquid yeasts as I believe the benefits outweigh any disadvantages– faster starts to fermentation, quicker completion time, harvesting clean yeast to save for future batches, and re-energizing old stocks, to name a few. But despite this personal commitment to making starters, I will be a lot less inclined to suggest that taking a vial home from the store and pitching it directly into one’s wort is an egregious error that guarantees certain doom, at least for most beers homebrewers are making. While I fully accept that these results would potentially have been different had I pitched a single vial into a RIS wort of 1.100 OG, my dogmatic conviction that a single vial of yeast cannot produce a tasty beer has waned. In this particular case under this particular set of conditions, it did, and I didn’t expect that.

Finally, the whole pitch-rate thing is something I’ll likely be a little looser with, as well. I’ve always adhered strongly to the recommended pitch-rates offered by my favorite yeast calculators, though now I’m beginning to question just how much a couple billion cells really matters. For example, if the calculator suggests my batch “requires” 300 billion cells but I’m only able to propagate 220 billion in my 2L flask, I’ll probably not worry much about stepping the starter up, as I’m not convinced the difference will have all that big of an impact.

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