Author: Marshall Schott

Brewer: Jake Freshour

To the delight of many, present company definitely included, lager beer appears to be gaining popularity among craft beer drinkers. The recent release of deliciously plain pale lager offerings from the likes of Firestone-Walker and Founders Brewing is evidence of this growing interest in a style with deep historical roots.

Noted as being the oldest independent brewery in Munich, Augustiner Brewery has been crafting deliciously crisp and quaffable lager beer since 1328. Those who have had the pleasure of drinking an Augustiner beer, especially their Helles or Pils, are likely familiar with the way the malt presents itself so beautifully, a characteristic many attribute to the particular strain of yeast they use. As a S. pastorianus variant, the Augustiner yeast performs well at cooler temperatures with manufacturers recommending to ferment with it between 50°F/10°C to 60°F/16°C, as anything warmer will lead to stylistically inappropriate ester development.

One such manufacturer is Imperial Yeast whose L17 Harvest is purportedly sourced from the Augustiner Brewery. After hearing good things about this yeast from others, most of whom used it as directed, I experienced the blasphemous urge to ferment with it a bit warmer. I fermented a couple non-comparative batches with L17 at ale temperatures and was quite pleased with the results, but that could easily be chalked up to my shitty palate, so we put it to the test!

| PURPOSE |

To evaluate the differences between beers fermented with a single pack of Imperial Yeast L17 Harvest at either 50°F/10°C or 66°F/19°C.

| METHODS |

When planning out the beers we wanted to serve at Homebrew Con 2018, a lager fermentation temperature xBmt was high on my list, and seeing as we had yet to test L17 Harvest, it was an easy choice. Huge thanks to Oregon homebrewer, Jake Freshour, who went through the trouble of brewing these beers for us to serve!

Nincompoop

Recipe Details Batch Size Boil Time IBU SRM Est. OG Est. FG ABV 5.5 gal 60 min 37.8 IBUs 3.9 SRM 1.050 1.011 5.2 % Actuals 1.05 1.008 5.5 % Fermentables Name Amount % Pelton (Mecca Grade) 9.75 lbs 95.12 Metolius (Mecca Grade) 8 oz 4.88 Hops Name Amount Time Use Form Alpha % Magnum 14 g 60 min First Wort Pellet 14.6 Hallertauer Mittelfrueh 14 g 15 min Boil Pellet 3.7 Tettnanger 14 g 15 min Boil Pellet 3.5 Hallertauer Mittelfrueh 14 g 5 min Boil Pellet 3.7 Tettnanger 14 g 5 min Boil Pellet 3.5 Yeast Name Lab Attenuation Temperature Harvest (L17) Imperial 72% 50°F - 60°F Notes Water Profile: Ca 59 | Mg 8 | Na 0 | SO4 89 | 63 Download Download this recipe's BeerXML file

Jake threw together a single large starter of Imperial Yeast L17 Harvest a couple days ahead of time that would later be split between 2 fermentors.

The night before brewing, Jake prepared by collecting and adjusting the full volume of brewing liquor then weighing out and milling the grain.

He then measured out the hops he’d be using.

Having set his heat stick on a timer, Jake was greeted by heated strike water when he started his brew day.

After mashing in with the full volume of liquor, Jake checked to ensure he hit the target mash temperature.

He then let the mash rest for 60 minutes.

At the end of the mash, Jake collected the pre-boil volume of wort in his kettle then boiled it for 60 minutes with hops added as stated in the recipe.

With the boil completed, Jake quickly chilled the wort with his immersion chiller.

A hydrometer measurement at this point revealed the wort was at the expected OG.

Equal amounts of wort were racked to identical fermentors.

The fermentors were placed in separate chambers, one controlled to 66˚F/19˚C and the other controlled to 50˚F/10˚C. After a few hours, both worts had reached their respective fermentation temperatures, at which point Jake pitched the yeast.

At 12 hours in, the warm fermented batch was visibly more active than the cool ferment beer.

A similar observation was made at 24 hours post-pitch.

The cool ferment batch developed a hearty kräusen around 36 hours post-pitch while the warm ferment beer was starting to die down a bit.

With both beers showing signs of halted fermentation activity after 3 weeks, Jake took hydrometer measurements showing they’d reached the same FG

The beers were kegged at their respective fermentation temperatures.

The filled kegs were allowed to lager in Jake’s cool keezer overnight before he fined with gelatin. About 3 weeks later, he pressure transferred the carbonated and clear beers to sanitized serving kegs that would be brought to Homebrew Con 2018. Unfortunately, in our conference haze, we forgot to get a picture of the finished beers, but we did snag a shot of Jake serving them behind the bar!

| RESULTS |

A total of 47 people of varying levels of experience participated in this xBmt. Each participant was served 2 samples of the beer fermented cool and 1 sample of the beer fermented warm in different colored opaque cups then asked to identify the unique sample. At this sample size, 21 tasters (p<0.05) would have had to identify the unique sample in order to reach statistical significance, though 25 (p=0.004) made the accurate selection, indicating participants in this xBmt could reliably distinguish a pale lager fermented with Imperial Yeast L17 Harvest at 50°F/10°C from the same beer fermented at 66°F/19°C.

The 25 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 14 tasters reported preferring the beer fermented warm, 8 said they liked the cool fermented beer more, and 3 people had no preference despite noticing a difference.

My Impressions: I attempted this triangle test 4 times while it was being served at Homebrew Con, the first two served to me by fellow crew members I got wrong, though I did pick the odd-beer-out on my following 2 attempts. Truthfully, I mostly resorted to guessing. Even knowing the variable and intensely focusing on ester presence, I thought the beers were far more similar than different.

Jake’s Impressions: As a huge fan of the crisp yet delicate nuances of a proper German Pilsner, I really anticipated the results of this xBmt with the L17 Harvest strain fermented 16°F/9˚C apart. I’ve also spent the majority of 2018 making multiple styles of traditionally fermented lagers. Upon tasting the beers individually, I noticed the cool fermented batch seemed to have a crisper and slightly more bitter finish that lingered just a touch. The warm fermented version tasted very similar upfront but finished with a slightly creamier and smoother mouthfeel with less overall perceived bitterness. In non-blind comparisons, I actually preferred the warm fermented version. I didn’t serve myself a proper triangle test at home, but when I did take the triangle test at Homebrew Con, I resorted to guessing… incorrectly. A humbling moment indeed. I don’t know that I would’ve been successful on subsequent attempts because the variances were so subtle, even with knowledge of the variable. I did not pick up any off-flavors in either, and the only differences I noticed were really in the hop finish and nothing major in the malt profile, aroma, etc. I am going to enter a few bottles of the warm fermented batch in a local competition next month to see how it fares. I am also going to make a few of my more recent award-winning lager recipes fermented warm with L13 Global and L17 Harvest to experiment a bit more. The part that excites me the most about these results and others previously isn’t trying to disprove someone/something, but rather opening up the ability to make lagers (at least with some tolerant yeast strains) at home fermented just like you would most ales and not be so intimidating to the beginner/novice homebrewer who thinks they need to buy a bunch of extra equipment to make their first lager.



| DISCUSSION |

As a traditional S. pastorianus lager strain that purportedly comes from the Augustiner Brewery, Imperial Yeast L17 Harvest and its counterparts from other labs is recommended to be fermented on the cooler end of the spectrum to ensure a clean fermentation profile. While other strains seem to be more robust than expected, blind tasters in this xBmt were indeed capable or reliably telling apart a German Pilsner fermented with L17 Harvest at 66˚F/19˚C from the same beer fermented at a more traditional 50˚F/10˚C.

On the surface, these results might seem obvious– tasters were able to distinguish beers because the one fermented warm clearly possessed more esters than the one fermented cool. Oddly enough, that wasn’t the consensus among those who were correct on the triangle test, and neither Jake nor I picked out any out-of-style fruitiness. I asked a few correct participants to describe what they perceived as being different and there was little in the way of consistency. A couple people noted the warm ferment sample having a slightly thinner mouthfeel, one person thought the cool fermented Pilsner had a little more sulfur on the nose, and a few responded honestly with, “They’re just a little different.”

Indeed, these findings suggest that fermenting warm with Imperial Yeast L17 Harvest may very well produce a beer that’s different than one fermented at a cooler temperature, but it says little about the impact on quality fermentation temperature has. In fact, a majority of correct tasters reported preferring the warm fermented sample, and given my personal experience fermenting warm with this particular strain, I certainly have no plans of stopping now!

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

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