Chapter 10 - What is Different for Brewing Lager Beer? What
makes lager beer different from ale beer, you ask? Well, the
main difference is temperature. Make that temperature and time.
No, there's three: Temperature, Time and Yeast. Let's start with
yeast. As discussed in Chapter 6 - Yeast, lager yeasts like
lower fermentation temperatures. Lager yeast produce less fruity
esters than ale yeasts but can produce more sulfur compounds
during primary fermentation. Many first time lager brewers are
astonished by the rotten egg smell coming from their fermentors,
sometimes letting it convince them that the batch is infected
and causing them to dump it. Don't do it! Fortunately, these
compounds continue to vent during the conditioning (lagering)
phase and the chemical precursors of other odious compounds are
gradually eaten up by the yeast. A previously rank smelling beer
that is properly lagered will be sulfur-free and delicious at
bottling time. Speaking of Time...