Our understanding of lager brewing was acquired from German textbooks, by attending brewing school in Munich, and through dozens of visits to German breweries where we sat with brewers, drank their beer, and discussed their methods.
What did we learn? We learned that lager fermentation requires more of almost everything: more yeast, more refrigeration, more tanks, more space, more time, and more patience. Although there is a lot more we could discuss, here are some key considerations when conducting a classic lager fermentation.
Cold and Slow
Lager yeast are valued for their clean, mellow character and crispness because they produce fewer fruity esters, fusel alcohols, and spicy phenols compared to ale yeast. This mellow character is possible because lager yeast can ferment at cold temperatures that would render ale yeast inactive. Cold temperature is the key factor that slows the yeast’s metabolism, which suppresses the production of metabolic flavor by-products.