As lager brewing has become more widespread in craft brewing over the past few years, brewers have looked to the past to decipher the mysteries of lager and the traditional methods used to produce it. From inherited wisdom about lagering a week for every degree Plato to seemingly arbitrary fermentation-temperature programs that take weeks to complete, it can be tough to separate myth from science.
Traditional lager brewing consists of interrelated techniques, each dependent on the others to create a system effective at producing quality beer within particular historical constraints. Using modern brewing science and engineering, we can assess these techniques on their individual merits and determine which are still needed to produce the highest-quality beer—and which can be modified or discarded.
Many brewers still think that traditional lagering times of two to three months, even for lighter beers such as helles and pilsner, produce better lagers. Is it true? To figure that out, we need to explore what lagering actually is and what it accomplishes.