All-grain brewers should boil their dunkel wort for 90-120 minutes. Extract brewers may employ a shorter boil, from 45 minutes to an hour. Add the bittering
hops 15 minutes into the boil — never earlier! German wort has plenty of proteins, and because uncoagulated proteins envelop unisomerized alpha acids, you
get less hops utilization out of your bittering hops. German brewers prefer to wait 15 minutes to let the proteins coagulate. Add the flavor hops 10-20 minutes
before the end of the boil (or as late as at shutdown). Add the aroma hops near, at, or shortly after the end of the boil.
Chill the wort to at least 55-65° F (13-18° C). The optimum primary fermentation temperature is 50-59° F (10-15° C). Use two packages, containers, or
pouches of yeast, or make a yeast starter to increase the yeast count. Vigorous primary fermentation usually takes about seven days. At a gravity of about 4-5°
P (1.016-1.020 SG), rack the brew into a secondary fermenter and leave it there for another two weeks.
Then transfer the beer for lagering. Lager your dunkel as close to the freezing point as is possible for about four to six weeks. You can lager at temperatures as
low as -2° C (almost 28° F). During lagering, the remaining yeast in suspension reabsorbs or reduces a good portion of its less desirable metabolic byproducts,
such as esters, aldehydes, fusel alcohols and diacetyl. This makes the beer taste clean and crisp. The yeast also scavenges oxygen, which increases beer’s shelf
life. After lagering, rack off the debris one more time and prime with about 1/2 cup of corn sugar or dried malt extract. Alternatively, add about half a teaspoon
of your priming agent into each 12-ounce bottle and siphon carefully out of the lagering container.
Horst Dornbusch is the author of “Prost! The Story of German Beer.”