Author: Marshall Schott

Imagine you’re perusing your favorite homebrewing forum, pictures of keezer builds, brew stands, pellicles, and deliciously full glasses of beer abound. Scattered among the images are discussions of advanced brewing techniques, prideful stories of brew days gone great, the occasional annoying link to someone’s blog, and questions… so many questions. As you continue reading, you notice the following post:

“Brewed first batch, didn’t come out very good, need advice”

Being the knowledgeable and noble person you are, you decide to help this person out and enter the thread to discover a bit more detail:

“I got a homebrew kit for my birthday and brewed my first batch about 6 weeks ago. We did everything by the book except secondary because somebody showed me a really cool experiment indicating it doesn’t help. The beer was bottled 3 weeks ago, the FG was 1.012, which was expected, and the carbonation is great. It just doesn’t taste very good, at all.”

As you scroll down the page to read, you realize there are no responses yet– this is your chance to be the first to give quality advice! You ready your fingers and start pecking away.

What is it you would type?

If you’re like most even quasi-experienced homebrewers, chances are you’d allude to the fact that fermentation temperature control is one of the most critical elements of producing quality beer. This concept, this truth, along with pitching the proper amount of healthy yeast, is what many homebrewers claim caused their beer to go from decently drinkable to downright delicious. 65°F to 68°F for ale and 48° to 55°F for lager beer, just a few degrees warmer promises the production of undesirable fruity esters or spicy phenolics, while pushing temps even higher will guarantee nasty headache-inducing fusel alcohols. I trust the large majority of us can attest to this, we’ve all made a batch where we let the ferm temp get away from us, and those beers sucked.

My curiosity, as it often does, got the better of me. I started wondering what differences might be noticed in two beers fermented at drastically different temps, though not too far outside the range provided by the manufacturer. Obviously there would be a difference, the question is how big would that difference be… or maybe it’s not all that obvious. There’s only one way to find out.

| PURPOSE |

The purpose of this xBmt is to investigate the qualitative differences of 2 beers made from the same wort, pitched with the same amount of the same yeast, and fermented at temperatures up to 12°F apart from each other.

| METHOD |

I thought for awhile about this xBmt, fully understanding that similar ones would be completed in the future. Since my focus was not necessarily on the impact of intentional hot fermentation, I wanted to select a yeast known for producing a particular ester profile when fermented warm. If you’ve ever checked out my recipes, you may have noticed I’m rather fond of using hybrid yeasts to make traditional lager styles, something many people swear against but in my experience works great. The catch is that I ferment them much cooler than the manufacturer recommendations, as I’ve found this produces a very clean beer with what I (and some competition judges) perceive as good lager character. For this xBmt, I decided to use one of my all-time favorite strains, WLP029 German Ale/Kolsch. The beer I selected is one I hadn’t made in a few months, May the Schwarzbier With You, a beer I hypothesized might come across less like a German black lager and more like a Porter when fermented warm.

In preparation for this xBmt, I made equal sized starters, splitting a jar of yeast I’d harvested from a previous starter between the 2 flasks.

A couple days later, I woke up bright and early to start brewing, my little brewer helping out as he often does.

The Carafa Special II and bump of Chocolate malt in the grist impart such a great color and smell.

The wort was boiled, hops were added, then it was chilled using my Hydra IC and, for the first time in a long time, a pump with recirculation arm.

A hair under 14 minutes later, the chilled wort was transferred to two 6 gallon PET carboys. As with all of these xBmts, I gently stirred the wort during transfer to ensure equal distribution of kettle trub in each fermentor.

Both carboys were then placed in a cool fermentation chamber to chill to my target pitch temp, which we now know may not matter all that much. Regardless, my goal in pitching at the same temperature was the reduction of extraneous variables- with yeast being pitched into wort that’s the same temperature, any variance between the batches can be more confidently attributed to fermentation temp.

It took about 6 hours for each carboy of wort to drop to 56°F, at which point I moved one of them into my house where the ambient temperature hovered around 65°F. The yeast was pitched. While not much visible activity was occurring 12 hours later, the temperature of the warm pitch batch had already risen to about 62°F.

After another 6 hours, there were definitely some noticeable differences and the warm fermented batch had risen to 64°F while the cool fermented batch was sittin’ pretty at a well-controlled 58°F.

A full day after pitching the yeast, both beers actively fermenting, the warm fermented beer had creeped all the way up to 68°F, a full 10°F warmer than its cool fermented counterpart. Pathetically, this made me a little anxious, nothing a few deep breaths, a couple pints, and the knowledge that this was still within the manufacturer’s recommended range couldn’t fix.

At 36 hours post-pitch, the warm fermented beer was pushing 72°F… shit. I’m embarrassed to admit the anxiety returned, I didn’t like the fact 5 gallons of one of my favorite beers was fermenting 12°F warmer than it should be. The things we do for “science.”

I failed to snap a picture of it, but I took note of the fact the warm fermented beer reached a solid 72°F at the 40 hour mark.

This is something I think is important to consider, regardless of the outcome of this xBmt. The ambient temperature in the room was 65°F yet exothermic heat produced as a result of fermentation brought the beer up to 72°F, a difference of 7°F. Keep in mind, this is a relatively low OG beer, the difference would almost certainly be greater if the OG was higher.

By the end of the 4th day of fermentation, the warm fermented beer had dropped back down to 68˚F, the cool fermented was smack-dab at 58˚F. Not long after this, the temp in the chamber began to ramp per my hybrid fermentation schedule in The Black Box.

Once the cool fermented beer reached the same temperature as the beer sitting at ambient, the latter was moved into the chamber where both remained a couple more days.

The time finally came to pull a sample to check the specific gravity, both were at 1.014 on the nose.

This was also the first time I got to sample the beers next to each other, no diacetyl was detected so it was time to crash, fine with gelatin, and keg them up.

The beers were ready to serve a few days later. This is where things get a little more interesting than usual…

| RESULTS |

Around the time I started having people evaluate these beers, I shot off an email to JP, host of the great newish show on The Brewing Network, Dr. Homebrew, which is billed as an “interactive BJCP scoresheet.” I proposed the idea of having judges Lee and Brian participate in the triangle test rather than just evaluating the beer. A few days later, I received an email back from JP saying it sounded like a fun idea and we agreed on a date. Last Thursday, January 15, I attended the live recording at the studio within The Hop Grenade in Concord, CA. Needless to say, it was a hell of a time for me.

I believe the podcast of this episode will be released on February 5, 2015, but you can watch the video on LiveStream now! If you do, you’ll notice that more than just Lee and Brian took the survey, and less than half were accurate. Is this any indication of how things will pan out in the end? Let’s crunch some numbers.

In all, 23 people participated in the triangle test, each blind to the nature of the xBmt. Participants were presented with 3 samples, 2 warm fermented and 1 cool fermented, then asked to identify which one was different than the others. With the exception of the Dr. Homebrew hosts, those who accurately selected the different beer were asked to complete another more detailed survey comparing only the 2 different beers, still unaware of the difference between them. Given the sample size, 13 people (p<0.05) would have had to accurately select the cool fermented beer as being the odd-man-out in order to say with any confidence the beers were actually different.

Of the 23 tasters, 9 (39%) correctly selected the cool fermented beer, 6 (26%) chose one of the warm fermented beers, another 6 (26%) chose the other warm fermented beer, and 2 (9%) indicated they perceived no detectable difference. Responses on the second survey, taken only by those who made accurate selections on the triangle test, provided no meaningful information– individual preference for aroma, flavor, and mouthfeel were essentially split.

My Impressions: I tasted these beers in 2 separate triangle tests setup by friends of mine, both times I was capable of picking out the different beer, something I’m certain is due purely to the fact I knew the nature of the xBmt. To me, the warm fermented beer had slightly more fruity ester character than the cool fermented beer, which I expected and knew to look for, while I experienced the cool fermented beer as being cleaner and somewhat more crisp. These could also have been lucky guesses.

| DISCUSSION |

If the results of the pitch temp xBmt surprised me, these results are downright shocking. I’m sure I’ll receive myriad recommendations as to how this could have been done better– use a different yeast, pitch at fermentation temperature, control this or that variable, all things I plan to get to at some point. But c’mon, never would I have believed that a beer fermented at 58˚F would taste so incredibly similar to one fermented at 72˚F+, I don’t care what yeast was used or style brewed. It makes little sense to me and leaves me with more questions than answers.

Does this mean I plan to start fermenting beers all willy-nilly with in regards for temperature? Hell no! And I certainly wouldn’t recommend others do this. Unexpected as these results are, I maintain that fermentation temperature control is one of the most important factors when it comes to the production of good beer. My hunch at this point is that a couple main factors contributed to the lack of crazy differences between the 2 beers in this xBmt, particularly the fact I pitched a good amount of active and healthy yeast into cool wort, which significantly reduced the chances of off-flavors that can be produced during the growth phase of fermentation. But this just a hunch, an educated guess that requires further experimentation, which I certainly plan to do. Until then, I’m left wondering… again.

If anything, these results would seem to suggest that pitching a bunch of healthy yeast into cool wort may help those who don’t have good temperature control make better beer. While the pitch temp xBmt yielded insignificant results, I’m hard-pressed to believe it wasn’t a factor in the present xBmt.

Perhaps these results didn’t come as much of a surprise to you as they did me or maybe you have your own experience with something similar. Please feel free to share your thoughts and ideas in the comments section below, or come join the conversation in the Reddit Homebrewing community. Cheers!

I’d like to extend a huge thanks to JP, Brian, Lee, Dan, Warren (Beardy), and the rest of the Dr. Homebrew/Brewing Network crew for allowing me to blow hard for an entire episode, it was a killer time, something I absolutely look forward to doing again in the future. I’m thinking about writing more about my experience on the show as well as the rest of what turned out to be a pretty rad beer weekend with friends, stay tuned if you’re into that sort of thing.

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| Read More |

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