Author: Marshall Schott
For the first fermentation temperature xBmt, I compared Schwarzbiers fermented up to 12°F apart using WLP029 German Ale/Kölsch yeast. Once it was revealed that a statistically significant portion of tasters were unable to distinguish between the 2 beers, I received numerous comments about the various factors that could have influenced these results– the yeast is too clean, the beer is too dark, the temp range wasn’t wide enough, warm fermented batch shouldn’t have been pitched cool. We had to start somewhere.
Truth is, with a variable like fermentation temperature, my plan all along has been to repeat this xBmt under different conditions using different yeasts in different recipes. In the weeks that followed publication of the first fermentation temp article, I paid close attention to the many recommendations I received for a follow-up xBmt, one of the most popular being to use a more characterful yeast with each batch pitched at their respective target fermentation temps. I also searched through some of my favorite homebrewing forums to discover the certainty with which some people claimed fermentation temp was key to making great beer– to be sure, my username was among those advocating for cool and controlled fermentations. Finally, I sought the opinions of a few dudes I regularly chat with and whose opinions I hold in high regard. The general consensus of this group was to use WLP002 English Ale Yeast and ferment it “no warmer than 72°F,” as a few reported experiencing intense ester formation around that temperature.
No warmer than 72°F, eh? Hah!
| 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 10°F apart from each other.
| METHOD |
Of all the suggestions I received regarding recipe choice, there was about an even split between a low OG English Ale and a low-moderate OG Belgian Ale. Since I had been pining for a tasty English Mild, that’s what I went with, figuring the lower alcohol content might help to emphasize any differences between the batches. To those who wanted the Belgian beer, I promise I’ll get to it at some point.
English Mild Recipe
| Batch Size | Boil Time | IBU | SRM | OG | FG | ABV |
| 11 gal | 60 min | 21 | 12 | 1.039 | 1.013 | 3.4 % |
Fermentables
| Name | Amount | % |
| Domestic 2-Row | 12 lbs | 80% |
| Crystal 60 | 1 lbs | 7% |
| Victory Malt | 1 lbs | 7% |
| Brown Malt | 8 oz | 3% |
| Pale Chocolate | 8 oz | 3% |
Hops
| Name | Amt/IBU | Time | Use | Form | Alpha % |
| East Kent Goldings | 28 g/~18.5 IBU | First Wort Hop | FWH | Pellet | 5.7% |
| East Kent Goldings | 21 g/2.5 IBU | 20 min | Boil | Pellet | 5.7% |
Yeast
| Name | Lab | Attenuation | Ferm Temp |
| WLP002 English Ale Yeast | White Labs | 67% | 66°F & 76°F |
A couple nights before brewing, I made a starter of WLP002, that quintessential chunkiness showing up within about 12 hours despite being a 5th gen harvested from prior starters.
I collected the entire volume of water and milled my grains the night before brewing, as I found this makes for a much smoother start to my early brew days. I was up around 5AM the following morning and mashed in about 20 minutes later. I was aiming for 153°F but duty called after I transferred the strike water to the MLT to pre-heat… the temp had dropped a little more than expected since I forgot to close the lid all the way. Whatever.
About 10 minutes into the mash, I found I nailed my target 5.2 pH as predicted by the Bru’n Water Spreadsheet, my preferred brewing water calculator.
After about an hour in the MLT, I filled my kettle with about 13 gallons of sweet wort, the FWH addition of EKG becoming immediately fragrant.
I cranked my burner to full blast, added a couple drops of FermCap-S to stave off a sticky boilover, then proceeded to clean my MLT. I added more EKG hops 40 minutes into the boil, waited another 20 minutes, then killed the heat and began to chill the wort.
Since my water is still cool enough to allow for chilling to my preferred ale fermentation temperature, I had to closely monitor the temp of the wort so as not to over-chill the half that would be fermented warm. My plan was to ferment the batches 10°F apart, this time pitching each at their target fermentation temps in order to account for any impact cooler pitch temps might have. For WLP002, I like to stick right around 66°F, which would mean the warm-fermented batch would be fermented at… gulp… 76°F!
That’s 8°F warmer than the top of the range recommended by White Labs. Shit. Outside of a couple Saisons, I’m pretty sure I’ve never let a beer get this warm during the first few days of fermentation. I chilled the rest of the wort, got it into a carboy, then placed each in separate fermentation chambers set to their respective temps.
Knowing that one of these beers was going to ferment so warm made me feel kinda funny. The large starter was split evenly and pitched. Signs of active fermentation began to show on the warm fermentation beer within just 4 hours.
At 24 hours after pitching the yeast, things were starting to pick up for the cool fermentation beer, from this point forward it looked similar to the warm fermented batch.
After 3 days of fermentation, both beers were showing signs of slowed activity. It was at this point I moved the cool fermentation carboy into the same chamber as the warm fermentation batch and turned the controller’s warming function off, allowing both to rest at ambient temperature, which was about 70°F at the time.
A hydrometer sample taken a couple days later revealed the warm and cool fermentation beers to be at 1.010 and 1.011, respectively.
After 3 more days and another hydrometer measurement that confirmed the first, I crashed the beers, fined with gelatin, and kegged them up. They were carbonated, crystal clear, and ready to present to participants the following weekend.
| RESULTS |
Over the course of 4 days, 22 people graciously donated their palates to this cause. All tasters were blindly served 1 sample of the cool fermentation beer and 2 samples of the warm fermentation beer then asked to choose the one they perceived as being most different. In order to reach a statistical significance, 11 (tasters (p<0.05) would be expected to accurately select the odd-beer-out, while 12 (p=0.017) participants were capable of doing so. While this does not allow us to conclude with certainly that fermentation temperature does indeed have a significant impact on the character of a beer, what this suggests is that the probability this data occurred by chance is significantly low enough to allow us to comfortably doubt the null hypothesis (that the beers are indistinguishable).
Similar to prior xBmts, the comparative survey completed by the 12 participants who were correct on the triangle test yielded data of seemingly little consistency. In terms of aroma, 5 people perceived them as being exactly the same, another 6 thought they were somewhat similar, and only 1 felt they were not at all similar; of the 7 who perceived some similarities, 5 preferred the aroma of the cool fermentation sample. Regarding flavor, 2 thought they were exactly the same, 8 said they tasted somewhat similar, and only 2 perceived them as being not at all similar; flavor preference for the 10 who noted some similarities between the beers was split right down the middle. Finally, 7 of the 12 tasters perceived the beers as being exactly the same when it came to mouthfeel, with 3 experiencing some similarities and 2 saying they were not at all similar; interestingly, of the 5 who reported noticing some similarities, 4 endorsed the cool fermentation batch as being their preferred, with comments suggesting it was “less watery” and “more rounded.”
Toward the end of the survey, the nature of the xBmt was revealed to those participants who were correct on the triangle test and they were asked to guess which beer they believed was fermented cool. Surprisingly, a rather large majority (8) wrongly selected the beer that was fermented warm.
Oh, and not a single comment on esters, phenols, fusels, or other yeast derived off-flavors.
My Impressions: I’m a bit perplexed. Sure, we reached statistical significance, if but by a mere skosh. But I’m telling you, if you were to serve me a pint of one of these beers immediately I finished a pint of the other, I’m certain I wouldn’t notice the change. The differences, which were subtle at best, only became apparent to my biased palate only as I focused on the tiniest of details. In fact, the only real difference I could pick up, the one aspect that allowed me to accurately select the odd-beer-out in 4/5 semi-blind triangle tests, is what I perceived as a difference in mouthfeel, as noted by a couple tasters. The fact more than half of those who moved onto the comparative evaluation really surprised, I figured that was the dead giveaway. I’m left wondering, despite the results, how the hell a beer fermented at 76°F with a notably characterful English yeast strain wasn’t the outright ester bomb I expected? Why didn’t a larger majority of these experienced tasters notice the difference immediately? Comparing the beers side by side, even knowing the nature of the difference, I found them to be nearly identical, save for the slightly watery finish of the warm fermentation batch. Yeesh.
| DISCUSSION |
Along with many others who’ve been in the hobby for awhile, I’ve stated multiple times that one of the absolute best things a homebrewer can do to make better beer is control fermentation temperatures. Admittedly, this sentiment was hugely influenced by those I look up to and whose opinions I value, though it was also based on personal experience– it’s true that my beer got better when I rigged up an old chest freezer to control the temperature of my fermentations. Sure, I made a few other process changes around the same time, like pitching healthy yeast starters, but the whole temp control thing, I mean, it just seemed so fucking obvious. It’s weird, as I sit here digesting the fact we achieved significant results for the second time ever, my focus seems to easily shift to how incredibly similar the beers actually were, how incredibly close were were to not achieving significance. Huh.
So, I’ll continue with my regular process of fermenting beer at cooler temps, primarily because it has worked for me, though I suppose it does feel sort of good knowing there’s some data to back this practice up.
What’s your experience been when it comes to fermentation temperature? Since starting this project, I’ve heard from a few folks who swear it doesn’t matter nearly as much as many of us believe, while others still maintain it’s an essential component of good beer production. Please feel free to share your thoughts in the comments section below.
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84 thoughts on “exBEERiment | Fermentation Temperature: WLP002 English Ale Yeast In A British Mild Ale”
I’d like to see a Xbeeriment along the same lines except dry yeast is used instead of a starter, since I imagine many of the homebrewers who ferment warm don’t have temp control, and also probably don’t have yeast starters.
It’s coming 🙂
What about an experiment where you have a beer at a stable, yet warmer temperature, a beer which is fermented at the recommended temperature for the style, and then one beer which is allowed to fluctuate in temperature, with zero control on the temperature.
I think that the key factor is temperature stability rather than the actual temperature to a certain degree.
I don’t see how dry yeast would make a difference, unless you are talking about changing the pitching rate and varying temperature.
I would recommend T-58 due to its flavor profile changing with temp.
Late to the game but I am also interested in this idea; I know there’s since been a dry lager experiment but I’d like to see some Ale ones. I brew small batch and usually almost exclusively dry yeast. I’m also in a third story apartment and have no fermentation chamber. Outside of Dec-Mar, ambient temp in my home is 74+ so I mostly brew Belgians, have gotten most Chico strain US beers to come out well, and have yet to make a single good English beer and subsequently quit trying. Windsor and S-04 have both produced disgusting phenol/ester nightmares bound for the drain.
try OYL Hothead. 98F is fine for it!
Nice work! I like this one. This experiment has to be highly dependent on the yeast strain I would think. I’ll be looking forward to more experiments like this with more strains and varying gravity worts.
Very interesting. I recently did something similar with WLP004 – albeit with less controls than you (my batches were split into different sized fermentation vessels) – and over several tests, I’ve been able to easily identify the warm ferment.
Jesus. Is there some extremely common piece of homebrewing advice that you are NOT going to debunk? Pitch temps, ferment temps, pitch rate, trub… one of these days I expect you to make a drinkable beer by dumping some brown sugar into a bathtub full of sea water, showing a packet of yeast to it and throwing the yeast away, and shouting: “FERMENT THEE INTO BEER!”
I think the message is clear, Nick: it’s not that hard to make good beer.
Maybe the “Brulosopher” and his cadre of “tasters” have shitty palates. Just kidding.
The results were significant, nothing really got debunked here! And truthfully, that’s not my intent 😉
Yeah but you got none of the crazy esters that people always, ALWAYS say you’ll get! Only 1 person said the aroma was significantly dissimilar. That’s debunking enough for me.
Here’s a thought… Perhaps the magic is in the control of the temperature (keeping it consistent within a “reasonable” range) versus a particular number. I’m betting that if you ran an experiment where one batch was allowed to just float around to whatever is ambient temperature, you’d see some differences. Or maybe we’re just not giving the yeast enough credit.
Could the fact that you’re using a 5th gen culture (that has acclimated to your local environment) have made a difference? Perhaps it’s now more tolerant to higher temps than the original WL batch?
This is the experiment I’d be interested to see. Controlled vs uncontrolled temps.
That’s already been done!
https://brulosophy.com/2015/01/19/fermentation-temperature-pt-1-exbeeriment-results/
This is exactly the comment I was going to leave.
This is surprising but I feel the problem here (and with a lot of these exbeeriments) is that they test on low gravity beers. Make a beer at 1.070 and I guarantee the differences will be more obvious, as the yeast are stressed from high sugar and then alcohol levels. I know you generally prefer more subtle, easy drinkers but a lot of folks (myself included) make much stronger beer!
fascinating as always.
Just to clarify, you set the temp of your fermentation chamber at 76F and then let it rip, correct? In other words, was the actual temp of the beer probably in the 80’s then?…accounting for the fact that fermentation activity raises the temp. That’s amazing.
I hate to suggest yet another experiment and be that guy, but, drawing on BeginngersBrew comment about the reality of homebrewers not having ferm chambers: wouldn’t it be cool to somehow test radical temperature swings and the impact that has on beer? For example, one beer is fermented at 70, while the other beer starts at 70, then drops to 60 next day, then back to 70 next day….get it? Because, as a homebrewer without a ferm chamber, that’s what I’m really concerned about – the down swings at night, the up swings during the day. And that’s why I’m considering a fermentation chamber.
I did set each chamber at the target ferm temps, and since I attach the probe to the side of the carboy, it maintained temp of the fermenting beer, not ambient.
The temp swing idea is a good one, something I’ll have to give some thought to, for sure.
But is there anything to limit the temperature from going above the setting? Is it possible that the fermentation drives the temperature above 76°F, and the controller doesn’t care because it doesn’t do anything unless the temp falls below setpoint?
My controller heats and cools, it’s a dual-regulator, so it controls the temp within 1F of my set point.
My money is on temp swings being the real issue here. So many homebrewers claim that their beer got better when they got a temp controller… And if absolute temperature doesn’t make a huge difference in beer quality (per Brulosopher), I bet it’s temperature consistency that makes all the difference.
I agree with the temperature swing theory. I don’t have a fermentation chamber, but I found a significant improvement after floating my carboy in water at fermentation temp. Even without doing anything to adjust water temperature, I have found it to stay relatively consistent through the active part of the fermentation. I know the actual fermentation is probably somewhat higher, but I am keeping it somewhat consistent by buffering the effects of the room temperature swings.
I agree with Matt Smith on the temperature swings. It was my understanding that the real benefit to a fermentation chamber was having consistent temperature. The up and down swings that naturally occur from day to day and the stress that that put on the yeast were the more significant issue rather than fermenting warm or cool. You could set up a profile in your black box to raise and lower the temperature by 10 degrees every 12 hours or so for one batch and leave the other batch at a constant temperature and see how they compare.
If the important variable is the temperature stability, rather than the absolute temperature, then how about testing with the carboy in a water bath, with no control? This is what I typically do, since I don’t have a controller or fermentation chamber. I find that it generally maintains my temperature (down as low as 62°F) for at least 36-48 hours after the krausen appears, before beginning to rise. Since I started using this method, my beers have been turning out great. Although I may just be getting better at it…
Hmmmmm. There is this….(Blatant plagiarism next)”Most brewers do not like the presence of diacetyl in their beer because it is a hint of a possible fermentationor contamination problem. But some brewers desire their beer to contain diacetyl in the final product. Forexample, Red Hook ESB has a characteristic diacetyl taste. This is most likely produced from their yeaststrain used or from the fermentation profile they employ. Some yeast strains, particularly flocculentEnglish ale strains, are known to be heavy diacetyl producers. Alternatively, the fermentation temperaturecan be crashed following terminal gravity, which would prevent the diacetyl rest from taking place. Lowlevels of diacetyl produced in this manner can be pleasant, and many classic beer styles allow for low levelsof diacetyl to be tasted in the beer.”Now for my two cents. Redhook ESBnot only ferments at 74 degrees, they use a HUGE yeast pitch. The beer is DONE fermenting in 58 hours and bottled immediately, maximum diacetyl formation and no chance for reduction.My experience has been that higher gravity beers are more likely to produce fusel/ketone flavors when fermented too warm and/or overpitched. Low gravity beers such as your English mild, not as much. Just not as much alcohol for bad outcomes. If you want to get real crazy ferment at 80 with a giant yeast pitch with a moderate OG beer. Then use the resultant beer to flavor your popcorn. I suggest you just make 1 gallon of the bad stuff…
I wonder what (if any?) impact kegging had on the outcome? Most of the non-temp-controlled beers I’ve tasted with off-flavors are never cold-crashed or fined, and they’re always bottle-conditioned.
But then here is an excerpt from Wyeast page: Effect of Pitch Rate on Beer Flavor Pitch rates, in addition to strain, temperature, and gravity, make a dramatic difference in the final flavor and aroma profile of any beer. The pitch rate will have a direct effect on the amount of cell growth during a fermentation. Cell growth decreases as pitch rates increase. Ester production is directly related to yeast growth as are most other flavor and aroma compounds.A low pitch rate can lead to: – Excess levels of diacetyl – Increase in higher/fusel alcohol formation – Increase in ester formation – Increase in volatile sulfur compounds – High terminal gravities – Stuck fermentations – Increased risk of infection High pitch rates can lead to: – Very low ester production – Very fast fermentations – Thin or lacking body/mouthfeel – Autolysis (Yeasty flavors due to lysing of cells) With some beer styles, where a complex ester profile is desirable (German Wheat) it can be beneficial to under pitch. Over pitching can often lead to a very clean beer lacking an ester profile (banana). This is a common problem with subsequent generations of Wyeast’s Weihenstephan Weizen #3068. Conversely, beers that require a clean profile should be pitched an an increased rate.
That’s what I was thinking… need to stress the yeast more with a lower pitch rate, to push them both to the edge of where issues start to develop. A big starter probably tends to hide some of the sins of poor fermentation temperature control.
I think what these experiments are showing is that when you do most of the things “right”, but get sloppy with one variable, it probably doesn’t matter much. It would be a more complex set of experiments, but perhaps more telling, to vary multiple control points while controlling to a larger “macro” variable.
In this case, controlling “yeast stress” by a combination of pitch rate, temperature, aeration, wort gravity, etc. The trick is coming up with an appropriate objective metric from these different variables.
Brewed a 1.074 IPA with S05. I temp controlled at a consistent 67, buddy took his half of the same wort home and fermented at ambient apartment temps. Only other difference was that he bottled, I kegged. When we compared a couple weeks later, his tasted like classic bad homebrew, mine tasted close to world-class. Maybe it’s the hops, maybe the temp swings, maybe the higher gravity, maybe the dry yeast, but there has to be something with fermentation control, they were just too different.
I’ve definitely had the fusel flavor in hot-brewed beers too. Maybe it has more to do with higher gravity stuff.
It’s just a hunch but I think it probably has more to do with temp swings at higher temperatures than just temp itself. Not to say that there isn’t a threshold at which things will absolutely get gross, but more to say that I think temp stability plays a larger role.
I agree. If I brew in my house our thermostat shuts off during the night and during the day while we are out. The temp can swing between 60 and 70 twice a day. I feel that this would likely have a greater effect than brewing at a consistent higher temperature. I would love to see an exbeeriment that compares a beer brewed with a constant normal profile to a beer that is swings from the min to the max recommended temperatures (at least during primary fermentation).
Just throwing a guess out there, I’m wondering if the use of a starter helps blur the line on a test like this. Everything you read in Yeast is how crucial the first 72 hours are. Through the use of a starter you are giving all your yeast a fresh dose of nutrients, and oxygen in the same house and at the same temp. You are pitching at the correct rate with very fresh and healthy yeast. The thought isn’t fully formed in my head yet. But I do wonder if this same experiment using just a vial from the LHBS in each would get you more black and white results. Thank you for doing this one though, in encourages me that through the use of a healthy starter I might not have to be quite so anal about my fermentation temps.
Do you think the high flocculation of WLP002 had any significance? Since that yeast sinks like a rock its often advised to rouse it during fermentation for full attenuation and clean up. Does it being stuck to the bottom of the fermenter with less beer contact mean the high temp was less relevant? Would be interesting to compare high temps with a wheat beer yeast 🙂
I really don’t know, maybe it did have an impact.
I think the comments about the gravity being very low is apt. IMO, single variables don’t seem to make as large of an impact as we’d all expect, but I do think they make a bigger impact at higher gravities.
After all, we make starters at ~1.040 OG because it’s optimal for the yeast for a variety of reasons, a wort with gravity ~1.040 is basically just a giant starter 🙂
That’s not necessarily true. A starter might have a max of 3 divisions with the use of a stir plate. And almost all of that is aerobic growth. In beer you will have many more divisions (much lower pitch rate in total volume) and only the the first 24 hours is aerobic growth. After that they have consumed most if not all of the oxygen and it’s pure anaerobic growth. I see your point about gravity being lower stress. But the other conditions aren’t the same as a starter.
This is a great point.
It might be interesting to to test the results of a controlled temperature vs. an uncontrolled. The move to using a fermentation chamber let’s you hold a lower temperature, but it also removes a lot of fluctuations you get if you’re just leaving your beer sit in a dark corner of the house or garage.
Been brewing almost 4 years and stick to primarily ale yeasts as my fermentation chamber IS my kitchen with huge temp swings. I brew varying gravities from 1.040 – 1.110 (1.110 is an oatmeal stout currently using wlp070, fermenting now – no results yet).. Point being, the only really bad beer I’ve turned out was a hefe that totally smelled / tasted like bananas (Wyeast 3068 Weihenstephen).. I’m really wanting to brew a belgian tripel (and have a solid recipe), but refuse to attempt that (or another hefe) until I get a ferm temp.. My experience has been that the dry ale yeasts I mainly use on the regular (us-05, s-04) have been very durable at varying ferm temps..
This could partially be due to the excellent health of the dry yeast. I’ve pitched dry yeast and found that I didn’t even have to shake the carboy much less use oxygen, and it crushed the beers and tasted great. They know how to engineer the dry yeast to make it really healthy.
Is it possible that temperature differences would be more likely to show up with a lower yeast pitch rate? The community seems rather convinced most of the time that if you are pitching a single vial of yeast, you are under pitching, which will stress the yeast. Perhaps the same experiment, but with just a single vial of yeast, with no starter, in the otherwise identical batch?
I think it’s totally possible
Poor guy. All that work to do an excellent, controlled, statistically significant experiment – and most of the comments ignore the experiment and instead suggest how they would do it differently! Sorry man. All in good fun though.
Great job on the ExBEERiment. I think these results are awesome.
Thanks for your continued passion to bring us great topics of discussion…gets us talking..
Cheers amigo..
I enjoy your blog and will continue reading it, but I’m of the opinion that great beer is the result of doing many things right. I’m betting that you could pick one thing and have that one thing be almost anything and end up with not much difference if everything else was done right. Just a thought.
One of the reasons behind the xBmts is to see how important single variables really are, I have plans to start testing multiple variables soon. Thanks for the support!
Truly interesting experiment. Now my brewing isn’t nearly as scientific nor as controlled, but when I brew my Hefe I notice a major difference fermenting at lower temps.
Between 15 and 17°C I get a brew that tastes very similar to some great German wheat beers. Above 18°C the esters change dramatically towards a Belgian style.
Great job on the xbeeriment. I sometimes over think/worry to much about all the parameters when brewing. Every time I read another one of your experiments that show almost no difference I am sure I spend to much time worrying about the details to much.
Just relax and brew.
Here’s my experience of something similar:
I once pitched 1 sachet of Mangrove Jack’s West Coast Ale too warm, at around 24c.
I then fermented it in my chamber at the lower temp of 18c and it took a good 12 hours to drop to that temp before it started to go up again.
The resulting beer was honestly like a banana milkshake. It was banana all the way.
So IMO it’s probably a common mistake that new homebrewers pitch the yeast at too high wort temps then put the carboy into a room that has a much lower ambient temp. The yeast starts off happy at those warm temps but then has to cool down before warming itself up again.
I have a pitch temp xBmt, the results were not significantly significant. My hunch is it has to do with multiple factors.
Thinking about it… 24C doesn’t sound out of place at all for what must be most homebrewers. Anybody without temp control ferments at “room temp”. Even when it’s -20C up here that still means 18-22C depending on the household. Let’s say 21C average. Actual fermentation temp must rise to 24C territory more often than not, no? My experience brewing without temp control would tend to confirm that those kind of temps are not much of a problem. But in summer it gets way higher than that. My summer beers are also a lot cleaner since I got temp control. I’d be curious in a more extreme setting. Keep it up!
To my mind, You kind of stop your experiment after three days, putting both at 70F, but what would have happen to taste if your keep primary and secondary to their respective temperature ? I think putting both at 70F, you allow the warm to recover during lagering ?!?
They were both done fermenting at the 3 day mark. I’ve actually compared a “ramped” beer to a “stable temp” beer, same batch, and there was seriously no difference. I think (I could be wrong) it’s pretty common practice to ramp temps a bit toward the end of fermentation to ensure complete attenuation and reduction in off-flavors.
I appreciate the experiment. But I think it may be yeast strain specific. Early in my young brewing days I made a Belgian Strong using WLP530. When it took off the temp went over the top of my ferm strip, beyond 84f. Opinions online were that it would be a “fusel bomb” or “very estery”. It was neither. At competition it was dinged for color and head, and for being too low in esters for the style. I’ve also used 3787, purportedly the same strain, from 62-66 with good results. My conclusion was that Westmalle has a big range. I made two batches, a Blonde and a Pale, with Notty that got to 73f. Both were nasty. So I keep Notty cool. Yeast are like woman, some like it cool, some like it hot, some are all over the place.
I fully believe it’s yeast strain specific, actually.
Be careful basing any conclusions on what a few competition judges noted on the scoresheets. Although the BJCP tries to maintain a high level of competency in judging, each judge has a different palate and different experiences and approaches to judging. You would need to get enough scoresheets with similar comments to approach a “statistically significant” opinion. That’s why the Brulosophy tastings are based on more than a dozen tasters.
I agree. I’ve had a brew judged in the same round of the same competition as both too old and too young. But the high temp ferment was also tried at my homebrew club, and others. Maybe not a dozen, but at least ten. No one noted fusels or high esters.
I’d like to see how the results would be using a smack pack or vial of yeast rather than the starter. Could the growth of the yeast also affect ester production?
I commented also on the last temperature xbmt. I have never controlled temperatures in any meaningful way aside from choosing the best location with the most stable temperature. My dad routinely made lagers at the same temp as ales without any control and they all turned out fine. Pitch enough healthy yeast and you are probably good to go on ignoring this on a homebrew scale (in my experience). I’m not saying it can’t turn your beer into a disaster, but with a decent recipe and good cleaning practices, aging can forgive quite a few sins.
This experiment baffles me, really! Along with your other experiments it seems as though you are encroaching on a single point failure. When I started brewing i made some stinking beers and only when I started meeting the required temperature control points throughout the entire grain to glass process (e.g. fermentation temperature control) my beer started to get really good.
I have only got off flavors from canned malt extract beer though (using the included yeast) and maybe only once or twice with all grain in the beginning (infections not included, sour weizen still tasted good). Maybe the canned stuff is just weird tasting by nature.
Do you think off flavors could be more related to significant temperature swings on a daily basis. Before creating a fermentation chamber the beer suffered from significant temperature swings 18-33 DegC (65-91.4) in my living room. Maybe constant temperature is the key rather than high or low fermentation temp.
You are continuously rocking the homebrew world mate, keep up the good work!
B
I do think temp swings could be at least one culprit of shitty homebrew, I have plans to test that one out soon 🙂
Thanks for the kind words and support. Cheers!
I’m in the same boat as Brewmaker, and was going to ask you for a slightly different experiment: controlled vs uncontrolled temperature during fermentation. I haven’t fully thought the temps or process but it would be something in the lines of:
– Set both carboys in a room/fridge/whatever @ 65ºF
– Pitch both at around 65ºF
– Make sure ond of them is kept at least at 65ºF, although can raise higher than that, while the other is not warmed up
The idea is that the non controlled one would cool down as soon as fermentation activity gets lower, dropping the yeast and ending up with less clean beer than in the one where the temperature is not allowed to drop.
Cheers!
Really interesting results here and I’m looking forward to seeing the planned follow ups to this. I wonder how much of it related to the strain, and how much is having an adequate pitch.
Also I wonder if temperature fluctuations have an effect. Alot of homebrewers who brew “too warm” have no temp control… Maybe swings, or very fast increases in temp when activity takes off has an impact?
My shift to using an old fridge to control fermentation temperatures coincided with my shift to brewing all grain as well, so it’s a bit hard to really compare between pre and post temp control, because the previous batches were kits or extracts anyway. It’s been working well for me to ferment my ales about 18C (64-65F), and lagers around 11C (52?F), so I’ll continue to do this as it produces good results.
There may be something in the theory of the temp being controlled as opposed to left to do whatever it likes, having less than the expected effect in the warmer fermented beer.
Cheers
This illustrates a major flaw in using anecdotal experience. Most of us have found our brewing results improve over time as we learn more and improve our processes. We don’t make improvements one at a time, but rather make use of everything we know at any given time to give us our best chance at a great result. I can’t imagine any practical situation where a novice brewer brews each new batch with exactly one improvement, and even if that did happen, how likely would it be that the ability of the developing palate to distinguish from one to the next would be noticed?
The Brulosophy experiments are a great effort at starting a scientific evaluation of various brewing processes, but these are done from the opposite side compared to a novice — that is, first do all the right things, and methodically do one thing at a time “incorrectly”. Once these single variable experiments are covered and there is enough confidence to move onto multiple variable experiments we may start to form some more practical conclusions.
Amen.
Fascinating. I’m with those who put it down to single Vs multiple factors. I experienced the increase in quality with temp control as a young brewer. Recently I had some issues and have been looking more closely into my process. I found that, even in the fermenting chamber, the beer was 3-4 deg C higher than the air temp at high krausen. I had a less than fantastic IPA that probably reached 26 deg C (78F). As a result, I have changed how I attach my temp probe and set it 3 deg C below my intended temp for the first few days then raise it.
I think that back in the day, before temp control, we had multiple issues. Most of us (especially in hot climates like mine where summer tap water is up to 25 deg C or 77F) struggled to get wort to pitching temp, then left it in a warm spot where it raged out of control, then subjected it to the vagaries of night/day temp swings. Result: Bad home-brew 🙂
Sounds like you just leave your temperature probe dangling in the air in the chamber. I think best accepted practice is to tape the sensor to your carboy — this will do a much better job of measuring the temperature of the beer itself.
I’d argue that the beer fermented at 76 was done fermenting much earlier than the one fermented at 66. And thus, the yeast had more time to condition and process diacetyl, acetaldehyde,and fusel alcohols. These processes also happen at a faster rate at a higher temperature. So, although more undesirable compounds were creating during the growth phase, they had more time to be taken care of by the yeast, and did so at a more rapid pace.
Fusels take a long time to go away in my experience. It takes a long time for a hot beer to taste better, and usually it’s better to just dump it.
I know this is old but just today I was using the WLP002 for a NEIPA and when I tasted the sample for a gravity read out of the graduated cylinder I didn’t notice anything. Brought some to work for a co-worker to try and as I sniffed out of the jar there it was, the esters…chemical, nail polish-ish with some fruity behind it. I didn’t change my temp profile on my brewpi (original yeast to be used was not white labs) and it hit above the recommended 68 degree mark for about 4 days as I was trying to encourage finishing fermentation.
We’ll see…my coworker didn’t necessarily notice but he wasn’t a master beer taster either.
I’m personally very doubtful the aroma you were detecting had to do with your ferm temp getting above 68F, unless you really let it get away from you during the earlier stages of fermentation. But I could be wrong. Curious to hear how the finished beer turns out!
I would think so too…it reminds me of my yesteryears (really not that long ago) when I had no temperature control (pre-brewpi) and it was always the thing that hit me. It was about 73-74 for about 4 days before I caught it.
I pulled some last night and while I don’t taste it per say, I do still get the whiff on my nose…fruity/apple (which is the mythical DMS typically) acetone/chemical hint.
Ill post back when its done, kegging on Thursday.
Alright, beer has been kegged for about a week and sure enough, no acetone flavors or smell. Its quite pleasant and I’ve gotten great anecdotal feedback. Most likely i was smelling the alcohol heat. Very happy with the finished product.
Side note, started listening to the podcast on my commute, great stuff! Really appreciate the conversation on the things you cover in experiments, keep it up.
Have you attempted this on hoppier beers?
Not yet, actually.
I ask because I had 2 beers fermenting and my temp controller gave out allowing the avg temp to venture up to 72 ambient. The same yeast was pitched to both the main difference was the hop/malt bill. The hoppy beer was super phenolic and the malty beer was fine.