What byproduct of fermentation does lagering help to settle out?

Lagering is a crucial phase in the production of lager beers and primarily allows for the settling out of sulfur compounds and other unwanted byproducts of fermentation. During fermentation, yeast produces various sulfur compounds, which can contribute off-flavors and aromas that detract from the beer's overall quality.

The cool temperatures associated with lager fermentation and subsequent lagering help yeast to flocculate, or clump together, and settle at the bottom of the fermentation vessel. This process not only allows for the removal of the yeast but also helps to reduce the concentration of sulfur compounds and other unfermented compounds that may have been produced during fermentation.

While alcohol is the main product of fermentation, it does not settle out during the lagering process. Hops contribute to the bitterness and aroma of the beer but are not a byproduct of fermentation, so they remain in the beer even after lagering. Carbon dioxide is also produced during fermentation but typically remains dissolved in the beer or, in some cases, can be released to create carbonation, rather than being settled out. Therefore, the primary purpose of lagering is effectively to improve the beer's clarity and flavor profile by allowing undesirable byproducts, mainly sulfur and other compounds, to settle out.