Most homebrewers begin by brewing ale, and their entire exposure to lager is limited mostly to American light lagers. Even many imports are often brewed to offend as few palates as possible. This sometimes leads people to think that by brewing a lager they're brewing a Budweiser.
The spectrum of delightful nectars belonging to the lager family is as varied and rich as that of the ale world, and the number of options for beermaking equally vast (and sometimes puzzling). If you prefer to stick to traditional lager styles, you're still free to brew beverages ranging from pale pilsners to malty Munichs and to choose from the complete range of hop bitterness and aroma. The small amount of fermentation by-products produced by lager yeast, combined with extended aging periods at very cold temperatures, make for a delightful beverage unprecedented in clarity and smooth, clean taste. These characteristics may account for the tremendous popularity of lager the world over.
In the 1800s lager brewing gained popularity in Europe when economical refrigeration made year-round production possible. Many emigrants to the United States brought their love for lager making with them, thankfully. During the 1850s through the 1870s, lagers took off in the States. The growth of lager breweries for the next two decades must have resembled what we see today with the microbrewery explosion, with more than 4,000 facilities in place by 1870. The following decade saw the introduction of commercial refrigeration equipment that nearly eliminated restrictions on both brewing season and location.
What Makes a Lager?
With beer now a generic term for all ales, lagers, and "hybrid" malt beverages, it's easy to get confused about the differences between ale and lager. The single biggest distinction between these two great families of malt beverages is the yeast used to make them. The key to any lager is bottom-fermenting yeast. Ales are fermented with top-fermenting yeast. But if you've made beers with both lager and ale yeasts, then you've noticed something pretty puzzling: When either yeast is used and wort is fermenting, the bubbles of carbon dioxide come off the bottom of the carboy.
One reason for this is that there are many millions of yeast cells in a five-gallon fermenter, and the yeast is actually distributed throughout the fermenter ¯ top, middle, and bottom. Many ale yeast cells rise close to the surface of the wort, but with lager yeast, a far greater percentage settle toward the bottom. During active, primary-stage brewing, these preferences in yeast migration can't really be seen.
Bottom-acting lager yeasts prefer much cooler working temperatures than ale yeasts. Because lager yeast works best in the 50° to 55° F range, the chemistry of fermentation is quite different than with ale yeasts, which work best at 60° to 70° F. The result: Beer that's lager, not ale.
There are many recipes and beermaking kits that specify lager yeast. Brewing these recipes by fermenting for three days at 70° F will not produce a lager. It's the difference between slipping quail in a stone oven to roast and popping chicken in the microwave. One says candlelit dinner for two, the other, hot wings. It isn't an issue of one being "better" than the other, but there's no question they are different.
The Lagering Process
For the homebrewer there are three goals of the lagering process:
- To allow yeast, haze-forming proteins, and any other suspended materials to drop out of the beer.
- To improve and mellow the flavor of the beer.
- To carbonate the beer.
After primary fermentation passes through high krauesen (the period of peak activity) and begins to subside, some brewers carefully remove as much of the trub-laden surface foam as possible. This is a good time to rack the beer to Cornelius kegs for secondary fermentation. Cornelius kegs are especially handy because they can be easily sealed and set up with an adjustable pressure relief valve. The tank is purged with carbon dioxide, the fermenter racked in, and the keg lid sealed.
The adjustable relief valve is set to maintain the tank pressure at about 10 pounds per square inch and attached to the "in" fitting on the top of the keg. Because this fermentation cycle is conducted under pressure, the beer also becomes saturated with CO2 at this time, a process called natural conditioning. After a reasonable period (about seven days) of secondary fermentation at normal temperatures (50° to 55° F), keg temperature is slowly reduced to 30° to 32° F. The lagering period, which can last from one to three weeks, provides ample opportunity for the yeast and haze particles to settle and for the beer flavor to further mellow.
An alternative carbonation method is to complete secondary fermentation using an airlock and carboy, then rack the beer to a Cornelius keg. For a five-gallon batch one to two quarts of actively fermenting "new" beer is then added, the keg purged with CO2 and sealed. In this procedure, known as kraeusening, the addition of actively fermenting beer has two purposes. One is to provide a fresh source of fermentables. The other is to add very active yeast to the beer to reduce the diacetyl, a buttery flavor produced during primary fermentation.
During any normal fermentation yeast make both desired and unwanted by-products. Beer style largely determines whether the by-products are expected, desired, or considered faults in the beer. Because it has very little if any positive taste contribution to beer, diacetyl is a by-product that most brewing processes are designed to eliminate.
Luckily, the same yeast that produces diacetyl also has the ability to reduce it. During a typical ferment cycle diacetyl levels rise as the yeast become more active, then lower due to yeast enzyme action. Controlling fermentation temperature keeps initial diacetyl production low enough so that, during secondary fermentation, most of it can be eliminated. This is one of the attractions of lager brewing, although ale brewers have no problem with diacetyl they follow correct fermentation procedures.
There are about as many ways to help the yeast reduce diacetyl levels as there are brewers. All techniques have two main themes in common.
- Ferment at low, lager temperatures to minimize diacetyl levels to begin with.
- Ensure that after fermentation is complete there is enough active yeast in the beer to reduce most of the diacetyl initially produced.
Besides diacetyl, yeast naturally produce a number of sulphur compounds you've probably already noticed when fermenting very active ales in the house. Many a new lager brewer has experienced the foul aroma of a high sulphur producing yeast and worried about contaminated beer. During the lagering process, the cold temperature of the beer combined with increased acidity cause tannins, proteins, and sulphur compounds to come out of solution and drop out of the beer. This action is a big part of the mellowing that occurs during the cold storage process.
With 10 pounds per square inch of pressure maintained on your Cornelius keg lagering tank, you can use a standard picnic tap to sample your product about every two to three weeks. After four weeks at 31° F, the beer should be quite clear. A straw-colored pilsner won't be brilliantly clear, but certainly by six weeks there should be only very slight haziness.
By ale standards lagering requires a lot of time. Unfortunately, most of that time has to be spent at 45° F or below and so requires some form of refrigeration. The fermentation process can last a few weeks and is best done near the optimum yeast temperature, usually 45° to 50° F. That means your fridge needs to be large enough to hold your fermenter, at least. If you want to have draft beer on hand continuously, your cooler will also have to hold one or two dispense kegs.
After secondary fermentation is complete and the beer is racked to your lagering vessel, you'll need to store the beer at 30° to 35° F for up to three months. For most amateur brewers this means buying a new or used freezer chest.
A nine- to 10-cubic-feet chest will hold four five-gallon Cornelius kegs. If you're shopping for a used unit, it's very helpful to take a few Corny kegs with you to make sure they'll fit into the fridge you buy. Two kegs, side by side, require a minimum clearance of 17 inches.
If you opt for a freezer chest, you'll also need to add a thermostat to the unit to keep the temperature high enough. Most freezers can't be set to temperatures much above 0° F, and you'll want both 45° to 50° F and 30° F as options. Many brewer's supply and mail-order shops carry easily installed thermostats for about $40 to $70. Look for one with a "deadband" of at least 3° to 4° F. That means the thermostat won't turn on the refrigerator until the temperature is about 2° F higher than the setpoint and won't shut it off until it's about 2° F lower. A narrower deadband means the thermostat cycles the fridge more often, trying to maintain a more precise temperature. This causes undue wear on the system. The temperature of four or five gallons of beer will stay very uniform even with a 6° F or more deadband.
Lager yeast isn't as energetic as ale yeast. There just never seems to be the huge burst of action that marks onset of high kraeusen, the large, foamy crest that marks a vigorous ale fermentation. Any distinction between the primary and secondary phases of fermentation is far more subtle for lagers. Note: Don't be tempted to get things going by warming up either your starter or your fermenter. The idea is to let the lager yeast do its work at cool temperatures, where yeast metabolism by-products are minimized.
After several days of steady fermentation, you will notice a reduction in kraeusen production, marking the end of the initial phase. The beer should be carefully racked into a secondary fermenter and the thermostat on the refrigerator clicked down about 1° to 2° F per day until stabilized at 30° to 35° F. Total time in the fermenter at this point will be between seven and 15 days. Now it's time to let the yeast do its work for about eight to 12 weeks. Be patient!
If you're an extract brewer, then all you need is a recipe and the specified ingredients. Your usual process will work just fine, except after the boil you'll want to chill to as cool a temperature as possible.
- 7 lbs. light malt extract
- 1 lb. Munich malt
- 4 oz. dark crystal malt
- 2 oz. chocolate malt
- 4 oz. Hallertauer hops, 2 oz. for 60 min., 1 oz. for 20 min., 1 oz. at end of boil
- Wyeast Bavarian Lager
Step by Step:
Add 3.5 gals. water to a 6-gal. pot (your brew kettle) and start the burner. Draw about 1.5 qts. of hottest possible tap water into a 2-qt. saucepan, and add the grains. Add just enough water to allow enough stirring to maintain temperature near 145° to 155° F.
As the water in the kettle begins to boil, slowly add malt extract, watching out for sticking and boilover. After all the malt is added, continue to stir for 10 to 15 minutes to ensure no extract gets burned at the bottom of the kettle. When the kettle seems to be under control, carefully strain the mini-mash into the kettle using a large (six-inch) kitchen strainer. Try not to get any grain in the kettle, but don't worry about a few grains that spill in. Discard the drained mash.
Add 2 oz. hops to the kettle in three or four additions, putting each additional amount in only after the kettle seems to be under control. Begin the kettle timer when a full rolling boil begins. Boil 40 minutes. Add 1 oz. hops and boil an additional 20 minutes, adding the last 1 oz. of hops just prior to the end of the boil, or even after the burner is shut off. Chill the wort as you normally do, and rack to the fermenter with chilled water to yield 5 gals. in the fermenter.
Cover the mouth of the glass carboy with a plastic sandwich bag and rubber band, or if you're using a plastic bucket as a fermenter, lightly place the cover on top (don't seal it!). Put the fermenter in your freezer chest or refrigerator and allow the temperature to stabilize to your starter temperature (which should be around 45° F). Pitch the starter.
Monitor fermentation activity, and notice when the kraeusen forms, how quickly it forms, and when it appears to reach peak activity. With daily checks you'll notice when there is a slight reduction in surface foam.
If you use a carboy, rack the beer to a clean Cornelius keg if you have one, taking care to leave all trub, both floating and settled, behind. Attach the pressure relief valve to the keg, set for 5 to 10 psi if it's adjustable. Rack to a clean fermenter and place an airlock if you don't have a Cornelius keg. Avoid aerating the beer, which can lead to diacetyl production and staling.
Maintain the secondary at the same temperature used for the primary ferment for about two weeks. You may want to pull occasional samples for gravity readings if you ferment in a keg, or just CO2 production if you ferment in a carboy. In one to three weeks there should be virtually no airlock activity at all. To remove diacetyl raise the fermenter temperature to about 55° F over a 24-hour period, and maintain at that temperature for 24 hours. Then lower the temperature two to five degrees per day to 30° to 32° F. Maintain at this temperature undisturbed for four to eight weeks for "normal" gravity beers or up to 12 weeks for bigger beers such as dopplebocks.
Decoction is the traditional German mash style for lagers, but temperature program (sometimes called upward step) mashing is probably most common among American microbrewers.
This recipe calls for a double decoction, but it can also be used with a temperature program or single infusion mash. It makes eight gallons.
Pt. Fermin Pils
- 5 lbs. German pils malt
- 8 lbs. Belgian pils malt
- 1.5 oz. Northern Brewer hops (7.3% alpha acid), for 90 min.
- 2 oz. Saaz (3.5% alpha acid), 1 oz. for 60 min., 0.5 oz. for 30 min., 0.5 oz. at end of boil yeast
Step by Step:
Add about 6 qts. of 145° F water to the grain, thoroughly wetting the mash. After mixing well, add another 3 or more quarts of 140° to 160° F water as needed to obtain a 95° to 105° F mash. Rest for 20 minutes, during which bring about 2 gals. of water to 150° to 155° F. Add half the 150° F water while gently stirring the mash. Measure the temperature while adding the remainder of the water to reach 122° F. Rest for 20 to 30 minutes.
After this protein rest is complete, use a large (six-inch) kitchen strainer to remove about one-third of the thick mash to a separate pot. Raise the temperature of this decoction over 15 minutes to 148° to 155° F and rest for 20 minutes.
Raise the decoction to boiling while stirring. Maintain a gentle boil for about 20 minutes, stirring to prevent scorching.
After the decoction boil is complete, return the decoction to the main mash in two or three steps, stirring gently and measuring mash temperature. Total mash temperature should be maintained near 150° F. This can be adjusted with a boiling water infusion, another small decoction, or external heat. Rest for 20 minutes.
Pull about one-half of the thin mash and raise it to boiling over 20 minutes. Boil for 5 minutes and return the decoction to the main mash. Stir the main mash gently and maintain at 160° to 168° F for about 15 minutes, then begin to sparge.
Bring the wort to a boil and add Northern Brewer hops. Boil for 30 minutes. Add 1 oz. Saaz hops and boil an additional 30 minutes. Add 0.5 oz. Saaz hops and boil 30 more minutes. Add last 0.5 oz. hops at end of boil.
Cool and pitch as in the Kurzbrau recipe.
Tips and Alternatives
Some brewers may not have access to a freezer chest that can be devoted to the most noble of duties, and regular refrigerators are very difficult to adapt to fermenting, lagering, and dispensing. There are several alternatives that might work for you.
If you live in cold-weather country, your basement may stay cool year-round. If fermentation can be kept in the low 50s, then lagering can be done in Cornelius kegs, which are more easily cooled than fermenters. This would provide a compromise that could produce good beer.
Another alternative is to simply scale down for lager brewing. A number of two- to three-gallon food containers are available that would more easily fit into a standard refrigerator.
At one time you may not have believed good beer could be brewed at home. Now that you know better, you should be ready to accept the challenge of making your own cool, satisfying lager. If you can manage the equipment needed for proper fermentation and cold conditioning, then you're ready. Just apply what you've already learned about brewing, and take the time to let the beer lager. Then sit back and enjoy the reward you deserve.