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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