I have a lager sitting in my lagerator at 35 degrees. What really happens during that period? I've seen some of the science behind the fermentation and mashing process, but not about the lagering. Heat gets things going, but what does the cold do?
Cold promotes yeast flocculation and the slowing of their metabolism to the point that they can continue to reduce acetaldehyde to ethanol and diacetyl to acetoin thus 'cleaning up' the beer. They also keep the beer in the reduced state so that the formation of staling compounds is prevented. Cold also promotes the coalescence of protein into globules large enough to precipitate and the formation of protein/phenol complexes which also precipitate out as does calcium oxalate.
Have you even noticed how lots of foods taste better after a night or 2 in the fridge? This melding of flavors also takes place in lagering beer.