Homebrewers are beginning to see the need to filter some beers to attain some level of clarity. But does it not remove flavour from beer? We discuss the issue here and also see if the beer is impaired in anyway by filtering.
The idea that filtering beer removes flavour is a long standing one among homebrewers and some craft brewers.
But is this true and is it not dependent on the beer style rather than all beers.
We discuss the pros and cons and look at reasons most brewers do not filter their craft beer.
To label filtration as an unnecessary and unwanted practice is like saying we should drink water as it comes from the river or dam without any consideration to suspended particles, turbidity and in some cases to toxic bacteria or poisonous heavy metals etc.
So what are some of the reasons going around against filtration of beer?
For one it is thought that filtration removes flavour.
When we have a closer look what is mainly removed is yeast which alters the balance of the beer.
Because yeast is needed for secondary fermentation filtration is considered unnecessary when bottling.
So what effect does removing yeast have on the flavour?
Yeast contributes a yeasty flavour, smoothness and body to the beer all positive attributes to most ales.
However, in excess, yeast can hide positive attributes in beer such as hoppiness aroma and taste and maltiness. In effect it can almost dull those desired characteristics found in certain styles of beer.
This was strikingly apparent when we ran a partial filtration trial in an overly yeasty commercial beer, without removing all the yeast.
All of a sudden the beer came to life with increased Amarillo hop flavour and aroma as well as sharper malty flavours.
A brewer can go to great lengths to add much hoppiness in beer and so should do what it takes to get it to shine through in the finished product.
But what about filtering all the yeast?
For bottle conditioned beers some yeast is required, however, it’s good practice to clarify all beer styles to a relatively “clear” consistency in order to reduce and minimise unsightly yeast sludge at the bottom of the bottle.
You do not need to see a haziness in order to know you have sufficient yeast required for secondary fermentation. In fact when I worked on clarity issues in a large commercial brewery we researched what the number of cells were that remained after fining and cold conditioning the beer . Although the beer appeared relatively “clear” to the naked eye there was less than about 200,000 yeast cells/ mL. remaining in the beer.
This is still sufficient for secondary fermentation although it may take at least 2-3 weeks to carbonate the beer at 20 deg. C.
So, it is not a good look to have a yeast sludge in the packaged beer that can come out when the final dregs of the beer are poured into a glass.
But for kegged beer, where secondary fermentation is not required to carbonating the beer (it’s done by forced carbonation from a CO2 bottle), removing all the yeast by filtration is a good idea, saving any yeast sludge being dispensed into the first couple of glasses.
One example of a commercially kegged beer showed a problem with excessive yeast that became the publican’s problem when first tapping the keg; too much yeast, an ugly sight, and potential flavour implications, as discussed above!
The publican had no choice but to “roll” the keg in order to spread the yeast in the beer and avoid lumps coming out all at once.
Guess which beer the publican will not want to buy next time.
So the question still remains; does removing all the yeast remove flavour?
In the Masterbrew brewing course we actually get a cornie keg of unfiltered craft beer and filter 1/2 of it using a home particle “water” filter to filter all the yeast out (as per the picture above).
We prepare each kegged beer for tasting and do a side by side comparison. It’s interesting to note that it is not clear cut which beer people actually prefer. In some cases people prefer the filtered beer and in other cases the preference could lean towards the unfiltered.
It is a personal choice but generally it is safe to say that “lager” beers are best filtered as the style dictates clean, crisp delicate flavours where neither yeasty, hoppiness or maltiness flavours dominate. “Ales” may do with a little yeast character, but as the example above showed not to have overly yeasty beer.
Another reason to leave the yeast in the beer is the concept of naturalness.
It is part of the fermentation process and the Germans even made a law called the Reinheitsgebot Purity Law of 1487, where the only ingredients that could be used in the production of beer were water, barley and hops. Of Course yeast wasn’t discovered yet so it was added later to the Law.
But this law can be quite restrictive and can lead to certain lautering and filtration problems associated with using wheat malt for example.
The wheat can add a “stickiness” to the wort and beer making it difficult to process and some cases almost impossible to process effectively.
By using a water type filter makes the beer “cleaner” in flavour and allows those beer flavours to shine through.
However, it also allows bad, unwanted flavours to become more evident should they be there in the first place, as a result of poor brewing practices or poor equipment selection and especially lack of temperature control and hygiene.
So the task at hand should be to learn how to minimise potential brewing problems and to use filtration as a means to remove unwanted yeast where the style or type of dispense calls for it.
Minimising yeast should always be the goal of the brewer, whether the beer is filtered or not.
It is well understood that keeping yeast in contact with the beer for long periods of time can even have an adverse affect on flavour when the yeast “autolyses” or breaks down releasing unsavoury flavours of its own like meatiness.
So in summary, it is not always a clear cut answer to think that filtration removes flavours from beer. It’s more a matter of flavour balance and intensity.
In some circumstances it is a necessity and in some styles it calls for a clear beer, especially for “lager” styles.
It is always better to err on the side of LESS yeast, even if not filtering and use cold stabilisation temperatures to remove yeast whether or not the beer is consequently filtered.
If you would like to join us in the 4 day Masterbrew course you will get proven methods to brewing flavour taint-free beer which when combined with filtration results in those good flavours to shine through.
P.S. In the last series of courses held in Wellington a special guest, Paul Wicksteed, was invited and he posted in one of his You Tube Videos about the course and how useful it is to learn about brewing.