On Food and Cooking

Once the wort has been boiled, it is cooled in
a broad open tank, where it picks up microbes
from the ambient air. The cool wort is then
poured into wooden casks that contribute
microbes from previous batches, and ferments
in the casks for 6 to 24 months. The
fermentation proceeds in four stages: an
initial growth of wild yeasts (Kloeckera and
others) and various bacteria (Enterobacter and
others) that takes 10–15 days and produces
acetic acid and vegetable aromas; the main
alcohol-producing growth of Saccharomyces
yeasts, which dominate for several months; at
6 to 8 months, the acid-producing growth of
lactic and acetic bacteria (Pediococcus,
Acetobacter); and finally the growth of
Brettanomyces yeasts, which produce a range
of fruity, spicy, smoky, and animal aromas
(see box, p. 730). The resulting brew may then
be blended with other lambics and aged to
make gueuze, with a wine-like acidity and
complexity; or blended with some ordinary