Filtering Before Bottling

Earlier this year Ashton Lewis participated in an “Ask Mr. Wizard” Q&A on BYO’s Facebook page where questions flew in over a two-hour timeframe. He provided quick and concise answers to over 30 questions. What follows is his original, short answer (in italics), plus some more information he wanted to provide when given additional time to expand on his thoughts.

Filtration at home is not the first thing I would consider doing to reduce sediment in bottled beer. The easiest thing to do (if you can do this) is to move your carboy to a refrigerator for one to two weeks after primary fermentation is complete to let gravity do its thing. If you are using powdery yeast (not flocculent) try using a fining agent. There are some products on the market today that are really effective and easy to use, for example BioFine.

This just happens to be a topic of particular interest to us at Springfield Brewing Company (in Springfield, Missouri) at the moment. Filtration is one of those love/hate things with some brewers, and some tend to love or hate filtration more than others. At Springfield Brewing Co. we have always been pretty neutral on the topic because we have a nice filter that is not a total pain in the neck to operate (not true of many filters found in brewpubs) and we offer both filtered and unfiltered beers. But beer filtration certainly has some drawbacks and we have been debating the pros and cons more lately.

The main problems associated with filtration are beer loss, the potential for oxygen pick-up and aroma and flavor loss, especially with hoppy beers. The major advantage with filtration is clear beer. Clarity really has a few components to it. On the surface, many consumers simply prefer clear beer because that’s what they are used to drinking. Some consumers don’t mind cloudy beer, but do mind chunks of yeast. Even clear beer in a bottle can have a layer of yeast on the bottom that can become chunky when poured, depending on the properties of the yeast and how the bottle was poured. Filtration addresses both of those issues, but at what cost?

On a commercial scale, filtration adds production costs in the form of labor, filtration materials and beer loss. Filtration also removes yeast, which is kind of the idea, but unfiltered beer with yeast is less prone to oxidation issues associated with air pick-up during filling than are filtered beers. Filtration also prevents bottle conditioning unless yeast is added back after filtration. Sierra Nevada is an example of a brewery that does the latter.

So back to the original question about filtration and my original answer. Filtration is not the first thing I would suggest for homebrewers because filtration seems much simpler on the surface than it is in reality. And from a cost point-of-view, there are much cheaper, simpler and generally effective methods available to
the homebrewer. Namely, cold conditioning in a keg or carboy and the use of finings.

The truth is that gravity is an awesome beer clarifier in that its force is great enough to cause yeast cells, and yeast flocs when fining agents are used, to settle out in a keg or bottle. The reason that gravity clarification is not common in large commercial brewing operations is that tanks are too deep for this method to happen in a reasonable timeframe. Homebrewers and small craft brewers do not have this problem. And the more I write about this I wonder if filtration would be the second or third thing I would suggest to a small-scale brewer in search of clear beer. Hmm, that patience thing is coming to mind.

Consider this; the biggest change in beer clarification technology used by medium and large craft brewers over the last 20 years has been the use of centrifugation. Beer centrifuges are continuous devices, some may describe them as bubbles in pipelines, that spin liquid at an angle. This increase in angular velocity increases the gravitational force within the centrifuge and increases the rate of yeast sedimentation. Cloudy beer enters one side of the centrifuge and exits through a different port, seconds later, almost completely clear. Some breweries use a polish filter to make centrifuged beer even clearer and others package without further clarification. The centrifuge only speeds up what can be accomplished at home in a few weeks in a cold environment.

Response by Ashton Lewis.