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Author: Marshall Schott

When I first started brewing at home, I started fermentation in a 6 gallon plastic bucket then transferred to a 5 gallon glass carboy a few days in for “secondary” fermentation. I realized a few years later that this secondary step was largely unnecessary and stuck with using buckets for quite awhile, swapping out the standard 6 gallon plastic pail for a few 8 gallon buckets with spigots. I began interacting with more homebrewers and realized many, if not most, were fermenting in large glass carboys, which I’d avoided out of fear of pain and love of limbs. I began researching the plethora of information and opinions (mostly opinions) regarding the differences between plastic buckets and glass carboys, my obvious purpose being to seek data that would confirm my decision to use buckets. Probably the most common argument against buckets is that they are more oxygen permeable than glass, while carboy haters spoke of the dangers of glass and often provided photographic proof. I sort of stopped caring.

Then one day it happened, I went to my fermentation chamber to prepare 2 buckets for kegging when I noticed the spigots on each were covered completely in mold. After a 15 minute tirade that included my non-beer-loving wife talking me out of ditching the hobby completely, I kegged the beers using an old siphon then threw the buckets in the recycle bin with plans to drop some cash on a few new carboys. While browsing the web that night, I was reminded of another option– PET carboys. Not only were they lighter and much less likely to sever a toe than glass, but they cost less and apparently were less oxygen permeable than buckets. Given my obsession with convenience, I threw the sterile siphon starter in my cart with 6 PET carboys, a few stoppers, and some airlocks. The next day, I sorrowfully removed the buckets from the recycle bin, washed them out real good, and figured I’d use them to measure out water and hold sanitizer solution.

It’s been a couple years since I started using these plastic carboys almost exclusively in my brewery and I have absolutely no regrets, but I began wondering again just what, if any, differences might be experienced in the same beer fermented in a bucket versus one of these PET fermentors.

| PURPOSE |

To evaluate the differences between 2 beers made from the same wort and pitched with the same yeast, the only variable being vessel of fermentation, with half fermented in a PET carboy and half fermented in a plastic bucket.

| METHOD |

I made 10 gallons of IPA (recipe similar to A Lil Slack IPA using a novel hop) next to another batch one early morning.

I selected one of my favorite ale yeasts, WLP090 San Diego Super Yeast, from my bank of harvested yeast and had the starters all ready to go by brew day.

Another typical brew day with all the wonderful sights and smells of this delicious hobby. One thing I really enjoy about first wort hopping is how aromatic the wort instantly becomes even before boil is reached.

Once the boil was complete, I transferred half of the wort into a PET carboy per my typical routine then, for the first time in years, racked the other half into a well cleaned and sanitized bucket (the one I haven’t used at all since the aforementioned fiasco).

Both fermentors were placed in my fermentation chamber, temp probe sandwiched between them, the wort was allowed to chill to my target pitching temp of 64°F, then the yeast was pitched. This is where I engaged my ale fermentation profile in The Black Box and let it do its thing. Both beers were active a day later.

I took an initial hydrometer reading 6 days later.

I was surprised to see the bucket beer with what appeared to be a specific gravity about .001 higher than the carboy beer. Would this come through in the final beer? What would cause this difference? I took another sample a couple days later and observed the same FG, it was time to keg these beers using my usual method.

I dropped the CO2 from 30 psi to 12 psi about 36 hours later, dumped the first 8 oz from each keg just to clear things up, then let them sit another 24 hours before taking a sample to taste. They definitely looked different at this point.

I start my siphon from the middle of the carboy, allowing me to avoid sucking up too much trub while kegging. With the bucket, the spigot is low enough that trub actually builds up in it and, despite my best efforts to clear it prior to packaging, quite a bit made it into the keg. The only real downside to this is that it took a few more throwaway ounces to get to the “clean” stuff, as the floaters were absent by the time the beers were ready for evaluation.

| RESULTS |

A total of 10 people participated in the tasting panel for this exBEERiment. Each taster was blindly presented with 3 beer samples and instructed to select the one that was different from the others. Each participant was served 2 samples of the beer fermented in the bucket and 1 sample of the beer fermented in the carboy. Those participants who accurately chose the beer that was different were then asked to complete a more detailed survey comparing just the 2 different beers. The tasting panel included homebrewers, Cicerone certified beer servers, and BJCP judges.

On the initial triangle test, 7 of the 10 participants (p=0.007) were able to correctly detect the different beer, a statistically significant rate that surprised the hell out of me. I later learned that probably the most qualified participant, a nationally ranked BJCP judge, was the only person to indicate the beers had “no detectable differences.”

Of the 7 tasting panel participants who completed the second survey, most agreed both beers were very similar in appearance with there being no overwhelming preference for either. While most concurred the beers were somewhat similar in terms of aroma, a surprising majority (5/7) selected the one fermented in a bucket as being more preferable, with one person commenting the carboy beer “smells slightly lighter.” What’s more is no one selected “no detectable differences,” suggesting fermentation vessel may have some impact on aromatics. Interestingly, the data on aroma is almost exactly swapped when it comes to flavor, as the majority seemed to prefer the taste of the beer fermented in the carboy. However, comments were somewhat confounding with 1 person describing the carboy beer as having “more malt flavor” and another stating it is “a lot hoppier.” In the end, 2 of the 7 participants believed there to be very little similarity in flavor between the beers, while the others said they were either somewhat similar (3/7) or exactly the same (2/7). Regarding mouthfeel, the majority thought they were at least somewhat similar with most (4/7) preferring the carboy fermented beer and only 1 participant indicating they perceived no detectable difference. Finally, when asked which beer was most preferred overall, 4 chose the beer fermented in the carboy, 2 chose the beer fermented in the bucket, and 1 did not choose due to there being no detectable differences.

At this point, the nature of the exBEERiment was revealed to the participants and they were asked a final question: which beer do you believe was fermented in the plastic carboy? Four of the participants, a small majority, incorrectly answered this question while 2 were accurate in their guess and only 1 said they were too similar to tell the difference.

My Impressions: In the numerous times I’ve tasted these beers, I’ve noticed they definitely aren’t exactly the same. At first, I was concerned maybe one of them picked up an infection, not because of off-flavors, but because my mind simply didn’t want to accept that they could possibly differ. After reviewing the results, I went back and tasted the beers again, clean palate and totally sober… yep, they’re different, if but just subtly. The bucket fermented beer seems to have a slightly richer flavor, whether from the malt or hops, I can’t be too sure. The carboy fermented beer seems somewhat cleaner to me, perhaps the .001 lower FG contributing to a crisper dryness, but I somehow doubt that’s all there is to it. Both beers are good and I’d be wary of selecting a fermentor based on these findings. For me, I’ll be sticking with PET carboys because I find them to be more convenient, plus no mold issues like I had with the buckets. Perhaps later I’ll borrow a glass carboy from a buddy and repeat this exBEERiment, as I know plenty of folks who still prefer it to either buckets or PET carboys.

| DISCUSSION |

I was always in the camp that believed the type of fermentation vessel one uses really doesn’t make a difference at all. In fact, I’ve made many of the same recipes in my old buckets as I have in my PET carboys and never noticed a big difference. These results were surprising to me in that it supports the notion that fermentation vessel may in fact impact the final character of the beer we make. Now, it doesn’t appear the differences are all that crazy or that either beer was necessarily significantly better/worse than the other, just that a panel of arguably qualified tasters were able to detect that something was different.

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| Read More |

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List of completed exBEERiments

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