S
accharomyces cerevisiae. It sounds like a baker’s
incantation—and in many ways, it is. In actuality,
this elongated mash-up of Latin and Greek (whichtranslates roughly to “sugar fungus of beer”) is the scientifi c
name for baker’s yeast. This microscopic fungus breaks down
starch into simple sugars and then devours those same sugars
and expels carbon dioxide and alcohol—all with the kind
of mindless effi ciency signature to single-celled organisms.
Through this tasty process of fermentation, yeast creates
fl avorful, air pocket-rich bread. Lest you take the miracle of
leavened bread for granted, know that this chemical reaction
has taken more than 5,000 years to comprehend and master.
Yeast has been around much longer than humans—give or
take 350 million years—but the fi rst use of wild yeast in bread
likely occurred 5,000 years ago in ancient Egypt, where the
earliest ruins of baking chambers and milling stones have
been found. But even though yeasted bread-baking appears
to be an ancient practice, the cause behind the rising effect
remained inexplicable. Wild yeast used by bakers often came
from their brewers and was called many different names, like
“emptins,” referring to leftover yeast slurry from cider and
beer, or beer “wort,” a mix of leftover grains and mash from
the brewing process. Once wild yeast took root in the dough,
bakers would recycle parts of the “old dough” into new
bread recipes in a system very similar to sourdough starter.
It worked, if in a slightly ineffi cient way that limited the scale
and production of the bread-baking process.