What Condition Your Condition is In
Beer is a complicated beverage to make, a challenge at every stage of the process. If you’ve been on a brewery tour, you know the basics: Malt is made into a porridge at specific temperature that converts starches to sugar, drained, rinsed, boiled with hops, chilled and fermented. After that rapid-fire sequence, things slow down as beer matures, smoothing the rough flavors left by fermentation and hopefully clearing up visually as well.
Unless we’re talking about a wit, weisse or others best enjoyed with a luminous haze, most drinkers tend to like their beer sparkling clear. Given enough time, it can clarify naturally, but we’re talking about beer, not wine, here, and brewers don’t have the luxury of unlimited tank time.
For hundreds of years, brewers have relied on clarifying agents, and more recently filtration. Early beers in the Middle East relied on straining devices, but these were designed to remove hunks of chaff and other floaters rather than the kind of clarifying we’re talking about here. It’s not exactly clear when clarifying agents—finings—became commonplace, but they were likely in use by 1700 or earlier.
There are a number of things a brewer might want to remove to make a more attractive and palatable beer. First and foremost is yeast. These microscopic fungi are harmless, but do make a beer appear muddy, and can sometimes take the taste in that direction as well. Yeast strains vary in their ability to flocculate, or clump together. A highly flocculent yeast will drop quickly and leave the beer clear and bright, but may in turn leave a bit more residual sugar behind. Less flocculent yeast makes a drier, more attenuated beer, as more of the sugar has been fermented into alcohol.
In addition to yeast, there are protein clumps, hop particles, tannins and dead yeast. None of these taste particularly great, so they all have to go.
Path to Clear
Clarification can be via either fining or filtration. The latter is just what it sounds like, but using highly specialized devices. Fining is a process that removes particulates by entrapping them and helping them settle to the bottom. There are many types of finings for different situations and targeting specific materials: particulates like yeast, excess proteins or other substances.
Long ago, winemakers discovered that proteinaceous matter such as egg whites does a great job at this, and in fact egg whites are still used to clarify wine. Protein casts a thin molecular net, electrically charged to attract yeast and other particles, helping them clump together and ultimately dragging them to the bottom.
Protein finings are still used in some breweries. A specialized gelatin known as isinglass, made from fish bladders, is traditional in English brewing, especially casks of real ale. Because isinglass is made from fish, vegetarians are happier when vegetable gelatin is used.
There are other types of finings as well, including silica gel and the unpronounceable polyvinyl polypyrrolidone (PVPP), which target proteins and tannins, respectively.
One newer type of fining has an unexpected benefit along with its clarifying properties. ClarityFerm, or Brewer’s Clairex, is an enzyme that removes haze-forming proteins. It attacks a chemical bond found in the amino acid proline, found in many proteins. Proline is prevalent in gluten, so the enzyme is a pretty effective destroyer of gluten. A brewery I work with has tested several of its beers that use ClarityFerm, and they have come in below the test’s detection limit of 10 mg/L, far below the U.S. federal threshold for “gluten-free” of 20 mg/L. As a result, gluten-intolerant people have a far greater range of choices and no longer have to put up with the sorghum syrup near-beers previously offered. The government hasn’t made up its mind on the rules for beer labeling, so most brewers use a term like “Crafted to reduce gluten” on their labels.
Finings are generally inexpensive, fairly easy to use and under the right circumstances can give great results. However, there are limitations. Since fining is a gentle coaxing rather than the hard barrier of filtration, it can’t remove material as thoroughly as a filter. So for situations where the beer really must be completely stripped of particulates, filtration is usually preferred.
Filtering technologies range from simple pad filters to slurries of fossilized diatoms. Although they are not filters, centrifuges may also be used to a similar effect, separating heavier particles from the liquid.
When managed correctly, filtration works great, but it may cause trouble. As the filtration gets finer, some desirable things may be removed along with the debris. Beer color, hop bitterness and body-building protein are large enough to get caught in the snare of the filter. A brewer must choose the settings carefully; even under the best circumstances, the brewer must accept a trade-off. To get the beer brilliantly clear, some desirable qualities may be diminished.
Many fining and filtration technologies can be used together in a specific sequence that can have as many as nine stages, each with a specific purpose. There are proprietary filter technologies, often going by the name “cold filtration,” that have the advantage of being less damaging to the beer while dealing with the haze. For the most part these are only used by large industrial breweries.
Hidden in Plain Sight
It’s important to understand that a filter is not a panacea. It can definitely shave a few days off the tank time for a beer, effectively increasing capacity. If the brewer is in too much of a hurry, immature beer can be prettied up quickly by filtration, but the unwanted flavors—especially acetaldehyde and buttery-tasting diacetyl—will remain, without yeast to clean them up. Removing the yeast also makes the beer more vulnerable to staling accelerated by oxygen. Yeast just loves oxygen, so if there is even a tiny amount inside the bottle, it will scavenge any available oxygen and keep it from causing harm. Some brewers leave a little yeast in the bottle for this very purpose.
The most extreme kind of filtration uses carbon or activated charcoal. Commonly used to purify water, carbon filters are used to strip away all traces of flavor, body and color. The result is a colorless alcohol solution, similar to a diluted vodka. Why would anyone want to do such a thing? The answer has to do with taxation. The U.S. government taxes premixed cocktail-type beverages at the high rate of spirits, partly as a means to raise the cost and make the sweet and fruity beverages less appealing to underage drinkers. As beer is taxed at a far lower rate, makers of these beverages can brew them and filter them clear, jumping through the loophole and making the products less costly. Such drinks are known as “flavored malt beverages,” or FMBs in the trade.
Some styles, like wheat beers, are best unfiltered for some pleasing, natural-looking haze; many are even carbonated with live yeast inside the bottle. This natural conditioning is also common in other ale styles, especially Belgian and British ones. Many craft brewers leave a small amount of yeast in the bottle, as its ability to scavenge and sequester oxygen makes the beer less prone to the ravages of oxidation that come, inevitably, with time.
Other beers should be sparkling clear. For most larger breweries this means some type of filtration. I usually prefer beer unfiltered; it has a little more mouthfeel and flavor. Lager is generally bright and clear, but in Germany they serve unfiltered beer in the brewery’s bierkeller. It is usually called either “zwickelbier,” after the tiny sampling tap on the conditioning tanks, or “kellerbier,” for obvious reasons. You do see it bottled or kegged occasionally; it’s worth seeking out for its fresher, fuller flavor.
All of this just reminds us how much of the brewing process stays hidden behind the scenes so we can enjoy delicious, beautiful beer while the brewers slave away at detail after detail. It’s a labor of love, a place whereat science and passion come together in perfect balance. About that we can be perfectly clear.
Randy Mosher is the author of Tasting Beer and is a senior instructor at the Siebel Institute.