essential roles of microbes and oxygen in the
traditional Orléans process (p. 773). Modern
methods for growing baker’s yeast and
producing penicillin were adapted to vinegar
manufacture after World War II, and now
produce finished vinegar in a day or two.
The Virtues of Acetic Acid
Acetic acid contributes two different flavor
elements to foods. One is its acidity on the
tongue, and the other is its characteristic
aroma in the nose, which can intensify to a
kind of startling pungency, particularly when
the vinegar is heated. The vinegar molecule
can exist in two forms: as the intact molecule,
and broken into its main portion and a free
hydrogen ion. The hydrogen ion gives the
main impression of acidity, while only the
intact molecule is volatile and can escape
from the vinegar or food, travel through the
air, and reach the nose. Both the intact and