Author: Jake Huolihan
In the quest for the clearest beer possible, many brewers utilize chemical fining agents where the method of action is rapid sedimentation of various unwanted compounds in the colloidal solution known as beer. Fining agents including gelatin, Biofine Clear, and Clarity Ferm offer brewers a super simple and relatively cheap way to clear their beer.
While fining agents can work quite well, they come not without a few issues– they don’t always produce the sought after brilliance, they require a fair amount of time to work their clarifying magic, and certain finings are made of chemicals some would rather not ingest. The solution for those looking to remove the haze in their beer and have it ready as quickly as possible is mechanical filtration.
Much more common on the professional scale, mechanical filtration generally involves running beer that’s finished fermenting through a device to remove particulate such that it’s clear when it arrives to the package. In the past, this practice was believed by many to remove desirable flavor and aroma compounds, to the point craft breweries often proudly displayed their “unfiltered” status as a way to distinguish themselves from macro breweries. Nowadays, perhaps due to advancements in brewing knowledge, it seems the hatred has eased up as more breweries have adopted the use of mechanical filters.
As an admitted lover of bright beer, I’ve relied heavily on fining agents such as gelatin for clarification. It’s been great in my experience, though it does require a few days to work and occasionally won’t completely clear a beer. As such, I was a bit hesitant when presented with the opportunity to try out a plate filter, but my curiosity about the impact it has on beer won out and I decided to put it to the test!
| PURPOSE |
To evaluate the differences between a beer that is unfiltered and one that is run through a plate filter at packaging.
| METHODS |
Having brewed mostly lagers for the past year I was longing for a nice Bass like ale around the house so I chose to go with my standard house bitter recipe for this experiment.
Hádor
Recipe Details
| Batch Size | Boil Time | IBU | SRM | Est. OG | Est. FG | ABV |
|---|---|---|---|---|---|---|
| 5.5 gal | 60 min | 49.8 IBUs | 10.2 SRM | 1.054 | 1.012 | 5.4 % |
| Actuals | 1.054 | 1.01 | 5.8 % | |||
Fermentables
| Name | Amount | % |
|---|---|---|
| Pale Malt, Maris Otter | 10.946 lbs | 91.63 |
| Crystal, Medium (Simpsons) | 12 oz | 6.28 |
| Crystal, Dark (Simpsons) | 4 oz | 2.09 |
Hops
| Name | Amount | Time | Use | Form | Alpha % |
|---|---|---|---|---|---|
| Hallertau Magnum | 10 g | 60 min | Boil | Pellet | 11.5 |
| Pekko | 20 g | 30 min | Boil | Pellet | 15 |
| Pekko | 20 g | 5 min | Boil | Pellet | 15 |
Yeast
| Name | Lab | Attenuation | Temperature |
|---|---|---|---|
| Pub (A09) | Imperial Yeast | 72% | 64°F - 70°F |
Notes
| Water Profile: Ca 91 | Mg 0 | Na 8 | SO4 149 | Cl 55 |
Download
| Download this recipe's BeerXML file |
A couple days before brewing, I made a single starter of Imperial Yeast A09 Pub that would be split between the batches.
After collecting my water and adjusting it to my desired profile a day ahead of time, I weighed out and milled the grain.
The following morning, I turned on the element to heat the entire volume of water for a single 10 gallon no sparge batch then weighed out the hops.
With the water slightly warmer than strike temperature, I transferred it to my mash tun and let it sit briefly to preheat before mashing in.
A check of the temperature revealed I was right on target.
Following the 60 minute mash rest, I collected the sweet wort in my kettle and turned the elements on to heat it up.
Once the wort reached a boil, I set a timer for 60 minutes and added hops as stated in the recipe.
When the boil was finished, I quickly chilled the wort with my immersion chiller.
I took a refractometer reading at this point that showed the wort was spot on my target OG.
The wort was then split equally into separate Brew Buckets.
My tap water was cool enough to chill the wort to my desired fermentation temperature of 66°F/19°C, so I immediately split the yeast starter between each batch and placed them next to each other in my chamber. With no differences between the beer at this point, it’s not surprising that fermentation was identical, as was their FGs 9 days post-pitch.
The warm beers were then transferred to CO2 purged kegs.
Given the nature of this xBmt, I skipped fining with gelatin and let the beers sit in my cool keezer n 1 psi of gas for 5 days before proceeding, the hope being to encourage the formation of any chill haze. I then pulled one keg out and ran the beer through a 5 micron plate filter, which I first purged with CO2 and Star San, directly into another sanitized keg that I’d also purged with CO2.
The process was surprisingly smooth with very little leakage. Immediately following the filtration step, I impatiently pulled samples from each batch for comparison.
Curious to observe the changes over time, I did similar comparisons at 5 days, 7 days, and 14 days, at which point they were presented to blind tasters for evaluation.
| RESULTS |
A total of 27 people of varying levels of experience participated in this xBmt. Each participant was served 2 samples of the unfiltered beer and 1 sample of the filtered beer in different colored opaque cups then asked to identify the unique sample. At this sample size, 14 tasters (p<0.05) would have had to identify the unique sample in order to reach statistical significance, though only 4 (p=0.992) chose the correctly, indicating participants in this xBmt were unable to reliably distinguish an English Bitter that was run through a plate filter from one that was unfiltered.
My Impressions: I simply couldn’t tell these beers apart and resorted to guessing in all of my blind triangle attempts. To my senses, they had the same aroma, flavor, and mouthfeel, despite the obvious difference in appearance. As for the beer, it was really quite delicious, and if I had to choose a preference, it’d go to the filtered version only because I think it’s prettier.
| DISCUSSION |
The contention that filtering leads to desirable compounds being stripped from beer makes sense on a superficial level, as it seems reasonably plausible that the particulates removed by filtration contribute to a beer’s character. However, results demonstrating blind tasters were unable to tell apart a filtered beer from one that wasn’t filtered suggests this may not necessarily be the case.
Is it possible the fear of filtration was motivated more by conjecture than fact? I spent some time researching the topic and everything I found arguing against filtration had nothing but belief and anecdote to back it up. The more cynical might wonder if this seemingly erroneous concern was a marketing ploy designed to distinguish macro from craft beer– mechanical filters aren’t cheap, after all, and convincing consumers to equate less-than-bright with quality is pretty genius. But who am I to say?
In addition to the obvious and predictable difference in clarity between the beers in this xBmt, the filtered version seemed to consistently maintain a stronger head with better lacing than the unfiltered batch. I’m not certain what would cause this, though it seems possible the filter removes certain lipids, leading to a fluffier foam.
Overall, I wasn’t terribly surprised by these results, my expectations admittedly influenced by the number of xBmts showing chemical fining has little impact on beer character. More exciting to me was learning just how good mechanical filters are rapidly clearing beer– never before have I achieved such clarity without a lengthy aging step, the beer looked beautiful and was ready to drink as soon as it was carbonated. While using a filter likely won’t become standard practice for me, I’ll definitely be using it in certain situations where commercial clarity is sought.
If you have any thoughts about this xBmt, please do not hesitate to share in the comments section below!
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40 thoughts on “exBEERiment | Impact Mechanical Filtration Has On A Strong Bitter”
This is probably a stupid question, but I assume mechanical filters would strip out yeast and thus not work when bottle conditioning beer?
Not at 5 microns. You have to go to .45 microns for a sterile filtration
.45 microns are usualy pre prefilters. To garanty a sterile filtration you must go to .22. But this does not really matter since young saccaromyces have arround 4um.
Is the filter difficult to use/clean/sanitize? This is tempting…
Do you have a picture of what the filter caught?
How expensive are the filters? And how often do they need to be replaced? Thanks for the xbrmt!
You’re supposed to replace them every time you use them. You can run a few kegs of beer thru them in one sitting though… I think they’re a few buck a pop
The filters are about $4 / pr and need to be replaced with each use.
The results don’t surprise me. I gelatin fine everything because I love drinking pretty, glassy beer. There’s something to be said about one’s visual perception enhancing your flavor impression. Gelatin fining is too easy not to do, literally takes 5 minutes out of my day.
You might repeat this experiment with a different style like a double IPA with tons of hops to see if you strip out hop flavor/aroma. I’ve heard anecdotes about this happening with mechanical and gelatin fining…
I used to use Gelatin and while it definitely doesn’t take long, I made the switch to Williams Warn Clarifying Agent (which is basically BioFine Clear). I brew in small batches, so a 1L jug off Amazon lasts me forever. Just 1 tbsp in the keg and after the cloudy initial pour, the beer is crystal clear. Love that stuff!
You have hit on something here that I have personally experienced. I am not sure if it the placebo effect, but I am convinced that my clearer IPAs have more perceptible bitterness and less aroma than the non fined/hazy beers.
Dude, if u left behind the yeasts then they not participate in the sensorial test. So is something more clean and let you taste more the malt and lupulo. Saludos!
How big were the particles you were filtering. In the wine industry, we filter down to .45u (microns) for sterile filteration. I think these home filter only filter to 5 microns which only clarify the beer. Even at .45u you cannot tell a wine was filtered.
Less particulate = less nucleation points so the carbonation breaks out more slowly and the head persists, IMO.
The only widely vocalized argument against fine filtering finished beer that I have heard is that it reduces hop aroma and flavor intensity. Seems like a recipe with heavy steeping / dry hopping would have been a more appropriate test. (Unless you were just craving a good fresh homebrewed bitter… I am definitely with you there.)
I am a big fan of the work guys! Thanks a ton for what you do.
On the commercial scale at least, the more major argument against filtration is beer loss. Depending on the setup, a brewery can lose 1-3 bbl of beer from filtering. That’s a lot of revenue not realized. But flavor is most definitely affected if the filter medium is 2 microns or less. Yeast are removed at this pore size, and they take with them adsorbed flavor-active compounds. Yeast aren’t removed at 5 microns, so it’s not surprising that this xbrmt was non-significant.
A homebrewer serving unfiltered beer from a keg that is not being disturbed is similar to a brewery serving beer on-premises straight from the bright tank. Filtration isn’t all that necessary of a tool until you have to consider transportation of kegs/bottles/cans. Even then, if you can guarantee a keg will have time to settle and that first pint of cloudy beer won’t be served to someone looking for a clear beer, it may not matter.
If i were you I would taste the stuff the filter caught to taste what it exactly removed from the beer. Maybe diluted with water or tasteless beer.
Thanks for doing this exbeeriment! I would love to have this same exbeeriment run with a hazy IPA with 16 ounces or so of dry hopping per 5 gallon batch. The arguments for not filtering seem to mainly have to do with hop aroma and flavor, which this exbeeriment could not really address due to the beer style. And, I’d love to see if the mechanical filtration would actually be able to clear a hazy IPA, since the previous exbeeriment with using fining agents was unable to.
I filter my beers on a case basis, and have done so since the early 1980’s.
The idea that filtering ‘strips’ is ludicrous. Flavor and aroma molecules are far too small to be trapped by a 2 micron or even a 0.2 micron filter element, and body comes from alcohol and unfermented carbohydrates, not suspended gunk.
Once you get the suspended gunk out of the way the beer is prettier and still delicious.
The number 2 reason I moved from bottling to kegging. Just that little, fine layer of “stuff” at the bottom of my bottles was enough to turn a perfectly looking glass of beer into a latte.
Thanks for doing this exbeeriment! It’s something I’ve been interested in after many batches of NE style “hazy” IPA. I would love to see this repeated with a “hazy” IPA with tons of dry hops added (16 oz or so for a 5 gallon batch). The main argument I’ve read regarding not filtering is to retain hop aroma and flavor in beer, so I’d like to see how the mechanical filter would affect a “hoppy” beer style. Also, I’d love to see if a mechanical filter could clear a “hazy” IPA, since in a previous exbeeriment, fining agents were not able to.
A filter would definitely clear up a hazy IPA. The only question is whether or not one pass on a 5 micron filter would be enough. I definitely plan to repeat this test on a nepa though, very interested in the results
You will likely clog your filter with a NEIPA. I don’t think there is any evidence that the particulate in a NEIPA holds extra hop aroma than the surrounding beer. The hop oils are already in solution. I think it will give you a harsher mouthfeel most likely
I have been waiting for this xBmt! Would you say one of those Pentek housings with a 1 micron filter would produce similar results or is a plate filter the way to go?
Is it significant that the results were so insignificant (p=.992). That’s way less than random chance.
Technically, no, that really doesn’t mean anything.
Wow this was cool. Has anyone used a filter and then bottle conditioned before? I know there would be plenty of yeast left in the beer, but does it take long to carb up?
Since you have the filter, why not do an exBEERiment comparing mechanical fining to gelatin? I don’t even know if a triangle test would matter in this regard, but it might have interesting results nonetheless.
I understand that there are not much difference if the particles are separated through gelatin or mechanical filters.
Isn’t the question if you can taste the difference between filtered and not filtered?
Sometimes it take a couple weeks, but I’ve generally been happy with the clarity I get without fining or filtering.
Nice enough experiment but I need to wonder why the beer was filtered before it had a chance to clear on it’s own. Having used filters in several industrial applications, the filtration might have been more efficient with a liquid having less suspended solids.
Just sayin’
David
I just did a brown ale in which I added pecans to the secondary. The pecans created some serious cloudiness in the beer. I believe the cloudiness is related to the oils in the pecans. Would this filter out the oil from the nuts? Looking at getting one of these this week to see if it helps…
Honestly not sure, I would think it would help
Good enough answer for me! Just clicked the buy button on MoreBeer! I need to do something as this is a xmas gift beer! Thanks.
Great experiment, but my question about this process comes right down to laziness. Was there still gunk at the bottom of the keg when it was empty? If the answer is no, is it less work to filter or clean the keg?
does anyone else trim their dip tube to avoid picking up “funk” from the bottom of the keg?
No, I bend them
Where did you get the understanding that 1 micron filtration will sterilize a liquid? I’ve never heard anyone claim that a filter larger than 0.45 microns would sterilize a liquid. More often 0.22 micron filters are used to sterilize.
Other Half brewery in NYC, one of the most popular NEIPA breweries out right now, puts every single beer through the centrifuge. Sam the head brewer and owner, saves it for the last part of tours he does just to watch people’s heads explode.