The term refers to a process of storing beer for an extended period at low temperatures. This maturation phase is crucial in the production of certain beer styles. The specific temperature range typically falls between 32 and 55 degrees Fahrenheit (0-13 degrees Celsius), and the duration can span from several weeks to many months. This prolonged cold storage allows the beer to undergo significant changes, resulting in a smoother, cleaner flavor profile.
The significance of this process lies in its ability to reduce the levels of undesirable compounds produced during fermentation, such as diacetyl and acetaldehyde. These compounds, if present in excessive amounts, can impart off-flavors like butterscotch or green apple. Furthermore, the cold temperature promotes the settling of yeast and other particulate matter, leading to improved clarity. Historically, this practice developed in Bavaria as a way to preserve beer through the warm summer months, utilizing cool caves for storage. This serendipitous discovery led to the development of the lager style, which is now one of the most popular beer styles worldwide.
