Filtering Homebrew
Filtration is a hot topic among homebrewers. The majority do not do it, and many are strongly opposed to the practice, claiming that it is unnecessary and detrimental. On the other hand, the majority of microbrewers filter most if not all of their output, regarding it as the best way to consistently produce clean-tasting beer. A minority of homebrewers agree, and I am on their side.
The Benefits of Filtration
It is quite true that filtration always removes a certain amount of color, body, and flavor from the finished beer, as well as reducing its foam retention. So a filtered beer will always taste and look different from the same beer unfiltered. Whether it will look or taste worse is another matter. Filtration removes colloids and yeast cells that add harsh and sometimes astringent notes to the flavor. A clear beer will almost always taste smoother than the same beer, prior to clarification. Only a few mildly hopped styles of beer, such as Belgian Witbier, benefit from the presence of hazy material.
This, however, is not really the question. The question is how to remove the yeast and other haze components and how thorough that removal needs to be. Many homebrewers feel that a slightly hazy unfiltered beer is fine, as long as it does not have a distinct “yeast bite.” They also contend that it is possible to clarify the beer adequately without resorting to a filter. I would agree, in the majority of cases. Given a low enough temperature and a long enough settling time, many beers will drop remarkably bright without any help. Once you pull out the sediment from the bottom with the first pint or two, the remainder of the keg will pour clear. Perhaps not as clear as filtered beer, but surprisingly close.
In my experience, the hands-off method of beer clarification requires (1) a cooperative yeast and (2) at least six weeks. It also requires that you leave the keg in one place from start to finish, because any movement will disturb the sediment on the bottom and recloud the beer. The yeast issue is big: few homebrewers want to limit their choices in this way. Time is an issue too. How many refrigerators do you have?
Practically speaking, if you only have one refrigerator, the choice comes down to filtration versus fining and settling. Both of these methods will allow you to make a clean-tasting ale in two to three weeks. I use both, and I used both when I was brewing professionally. I found that filtration is more consistent and usually faster. Settling works, but the effectiveness of finings depends on proper handling, which may not be easy. It also depends very much on wort quality. The cleaner the wort that went into your kettle, and then into your fermenter, the clearer and faster the beer will drop. In other words, if you are looking to avoid filtration, you’d better do everything right on brew day.
The Drawbacks of Filtration
As far as the drawbacks of filtration go, this is in large measure a matter of design — in other words, recipe formulation. If filtration is a regular part of your process, then as you develop your beers you will automatically compensate for the color, body, and flavor changes. You’ll use a bit more colored malt in the darker beers, perhaps a touch more hops in some of the aggressively bitter beers, maybe an extra ounce of flaked barley or Cara-Pils® in a heavy beer. Filtration does not take away that much. It certainly will not turn a pale ale into a light lager. Blackstone St. Charles Porter has been winning awards for 15 years, and for 15 years it has also been garnering criticism from the judging panels. From the judges who think it is not medal-worthy, one charge is consistently laid against it: it is too heavy, too malty, and too hoppy for the style. Its foam retention has never been criticized. St. Charles Porter is a filtered beer and always has been.
That is all I have to say about this question. I believe that filtration is something every brewer, sooner or later, should learn; it is a powerful tool and, in my view, a requirement in some situations. On the other hand, it is possible to brew great beer without ever coming near a filter. You just have to accept the limitations that come along with that decision.
Sheet Filters and Cartridge Filters
There are two types of filters that are widely used for homebrew: one is the plate-and-frame sheet filter, and the other is the ordinary household water-filter housing with a cartridge. Both work, and both, as you would expect, have their advantages.
The advantage of the sheet filter is that the material is specifically designed to filter yeast and colloidal matter out of fermented beverages. The sheets are strictly single use, but the cost is reasonable, and the frame is easy to take apart and clean. There are three disadvantages of sheet filters. First, the small units sold for homebrew will not take pressure, so it is impossible to filter carbonated beer through them. Most homebrewers filter their beer flat, so this is usually not a concern. Second, by their design the units inevitably leak a little. Losses are small, but you have to place the unit in a shallow pan to avoid making a mess. Again, this is easy to deal with. Third — the most serious drawback — is that the base material of the sheets is cellulose. It is an excellent filter medium, but it needs to be flushed with water prior to use, in order to remove loose fibers and avoid a papery taste in the filtered beer. Again, this can be dealt with. Best practice in any case is to sanitize the filter before the run, and flushing can be incorporated into the sanitizing routine.
Cartridge filters do not leak if properly assembled, and the housings will take pressures well above what is encountered in handling carbonated beer. The filter media come in a broad range of types, but many are based on inert materials that impart no taste to the finished beer. Cleanup of the housing is quite simple. Cartridges can be cleaned by back-flushing and reused, potentially for dozens of batches, which cuts down on cost. The problem is finding a filter cartridge that actually works. Many types of cartridges are available, and I have tried several. In my experience, micron numbers mean very little. The word “absolute” should mean something, but unfortunately, even among absolute rated filters there are large differences in performance. My experience with filters designed for water has been uniformly unsatisfactory. I have tried several types that failed to deliver bright beer. I finally shelled out for a pleated unit from The Filter Store, and I am happy to report that the one I chose works as advertised. Manufactured by Graver Technologies, it is designed for filtering beverages. As of this writing, the 0.5-micron unit costs $45 plus shipping. The 1-micron unit, which I have not tried, is a few dollars cheaper. I am sure there are other filters out there that also work, but if you want to filter beer on the cheap, you may have to search long and hard.
Filter Housings
Filter housings are available from many sources. Clear bodies often cost more, but I feel they are worth it because they let you observe the flow of beer through the filter. You can find them online at a reasonable cost. A pressure release valve is not absolutely necessary but can be helpful to deal with foaming, especially if you want to try to filter carbonated beer. You will also need two keg couplers, some tubing, and barbed adapters for the housing.
A word of advice on filter housings: buy a new one for your beer filter and use it only for beer filtration. Take care of it. Never forget that what makes the seal between the “dirty” and “clean” (input and output) sides of the unit is a pair of simple knife-edges cast into the housing pieces, and the neoprene washers on either end of the cartridge. The seal depends entirely on compression. The knife edge therefore must be perfectly smooth. Take care how you store it. Also, to extend the life of the cartridge washers, I suggest that you assemble the unit and tighten it down only for filter runs, and otherwise store it covered but open.
How to Fllter
Filtration is basically a process of using carbon dioxide pressure to push the beer out of one keg, through the filter, and into a second keg. As with any brewing operation, the most important thing is to make sure that everything that touches the beer is clean and has been sanitized ahead of time. The next most important, with fermented beer, is to minimize air pickup during filtration. These goals point to a tedious but straightforward prep routine. The easiest way I have found to sanitize the filter, lines, and kegs, is to basically do a “prefilter run.” I use a 40 ppm activated Oxine solution as my filter sanitizer.
The Routine is as Follows:
Step 1. Set everything up and put all equipment together as for the filter run. Make sure the gas valve on the regulator is closed. The racked beer keg connects to the input of the filter. The output plug of the bright beer keg connects to the output of the filter. Leave the keg lids off or hanging loose.
Step 2. Make up 5 gallons (19 L) of activated Oxine solution in the racked beer keg. Set the carbon dioxide regulator to 6 PSI or whatever the filter instructions recommend. Put the lid on the keg and then open the gas valve on the regulator. Push the Oxine solution through the filter housing into the bright beer keg. At the end of the run turn the filter upside down to empty it as well as possible.
Step 3. When carbon dioxide starts bubbling up in the bright beer keg, detach the beer and gas hoses from the racked beer keg. Also detach the beer hose from the output of the filter. Put the lid on the bright beer keg, put the end of the beer hose in a bucket, then connect the gas hose and push the Oxine solution out of the keg into the bucket. When finished, disconnect the gas hose from the keg and close the regulator valve. Set the bucket of Oxine aside. Reattach the bright beer hose to the filter output.
Step 4. Now it’s time to filter. Rack the cold beer out of the fermenter into the racked beer keg.
Step 5. Close up the keg and reconnect it to the gas. Leave the racked beer hose connected to the filter, but not to the keg.
Step 6. Purge the headspace of air. Adjust the regulator to 6 PSI. Then open the gas valve and pressurize the keg full of racked beer. Release the pressure by pulling on the ring attached to the relief valve. If the relief valve cannot be operated manually, you will have to disconnect the gas line and press down on the poppet of the gas plug. Repeat three times.
Step 7. With head pressure at zero, reconnect the racked beer line to the keg. Open the pressure relief valve on the bright tank and leave it that way until the filter run is over. Set the carbon dioxide pressure to the lowest value recommended by the filter instructions. Stop for a minute and double-check that everything is connected together just as it was when you sanitized the filter. Then open the gas valve and run the beer through the filter. If necessary, increase the pressure as the run goes along, but note the maximum pressure specified. The Filter Store states that the maximum is 35 PSI. With its 0.5-micron filter cartridge, filtration should take 10 to 15 minutes. I find that 6 PSI is enough to push the beer through the filter.
Step 8. When all the beer is in the bright keg, close the pressure relief valve. Disconnect the gas hose from the empty keg, set the regulator to
30 PSI, and attach the hose to the bright keg. Turn on the gas. Purge the headspace three times, but this time leave it pressurized after the last fill. Set it in the beer fridge and proceed to cleanup.
Step 9. To clean a cartridge filter, make up 1 gallon (3.8 L) of PBW solution in the bottom of a 5-gallon (19-L) bucket. Disassemble the cartridge housing and clean by hand. Put the hoses and couplers in the solution to soak. Make sure they are filled. The cartridge itself is best cleaned by soaking. I leave it in the bucket for an hour, spinning and swirling it several times. To keep it submerged, I set a small plastic bucket over it — this is just heavy enough to hold it under.
The Graver cartridge has a polypropylene mesh wrapped around the pleated element, and this protects it. If you have a cartridge without such a protective sheath, you will have to weight it down in some manner, but be careful not to bend or fold the pleats. While the cartridge is soaking, clean all hoses, racking arm, kegs, and fermenters by hand. On plastic, use nothing rougher than a sponge and avoid scrubbing. Let the PBW do the work. The best way to clean small tubes, including the dip tube in a corny keg, is to siphon or push solution through them, then stop the flow and leave them to soak a while.
This story is excerpted from the new book Brew Like a Pro © by Dave Miller, Illustration by Steve Sanford. Used with permission from Storey Publishing.
